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Clinical outcomes in patients with atrial fibrillation and frailty

Research article
Open Access
Published: 24 December 2020

Clinical outcomes in patients with atrial fibrillation and frailty: insights from the ENGAGE AF-TIMI 48 trial

Chris Wilkinson, Jianhua Wu, Samuel D. Searle, Oliver Todd, Marlous Hall, Vijay Kunadian, Andrew Clegg, Kenneth Rockwood & Chris P. Gale

BMC Medicine volume 18, Article number: 401 (2020) Cite this article

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Abstract

Background

Atrial fibrillation (AF) is common in older people with frailty and is associated with an increased risk of stroke and systemic embolism. Whilst oral anticoagulation is associated with a reduction in this risk, there is a lack of data on the safety and efficacy of direct oral anticoagulants (DOACs) in people with frailty. This study aims to report clinical outcomes of patients with AF in the Effective Anticoagulation with Factor Xa Next Generation in Atrial Fibrillation–Thrombolysis in Myocardial Infarction 48 (ENGAGE AF-TIMI 48) trial by frailty status.

Methods

Post hoc analysis of 20,867 participants in the ENGAGE AF-TIMI 48 trial, representing 98.8% of those randomised. This double-blinded double-dummy trial compared two once-daily regimens of edoxaban (a DOAC) with warfarin. Participants were categorised as fit, living with pre-frailty, mild-moderate, or severe frailty according to a standardised index, based upon the cumulative deficit model. The primary efficacy endpoint was stroke or systemic embolism and the safety endpoint was major bleeding.

Results

A fifth (19.6%) of the study population had frailty (fit: n = 4459, pre-frailty: n = 12,326, mild-moderate frailty: n = 3722, severe frailty: n = 360). On average over the follow-up period, the risk of stroke or systemic embolism increased by 37% (adjusted HR 1.37, 95% CI 1.19–1.58) and major bleeding by 42% (adjusted HR 1.42, 1.27–1.59) for each 0.1 increase in the frailty index (four additional health deficits). Edoxaban was associated with similar efficacy to warfarin in every frailty category, and a lower risk of bleeding than warfarin in all but those living with severe frailty.

Conclusions

Edoxaban was similarly efficacious to warfarin across the frailty spectrum and was associated with lower rates of bleeding except in those with severe frailty. Overall, with increasing frailty, there was an increase in stroke and bleeding risk. There is a need for high-quality, frailty-specific population randomised control trials to guide therapy in this vulnerable population.

Trial registration

ClinicalTrials.gov NCT00781391. First registered on 28 October 2008

Peer Review reports

Background

Atrial fibrillation (AF) affects at least 10 million people in Europe [1]. The incidence and prevalence of AF increases with age [2] and is more common in patients with frailty [3, 4], a condition characterised by a decline in a person's biological reserves and deterioration in physiological mechanisms that render them vulnerable to a range of adverse outcomes [5,6,7,8,9]. Frailty provides an insight into biological age and is more useful than chronological age in predicting adverse events and guiding clinical care [10,11,12,13,14]. Frailty is commonly identified using either a frailty index or a frailty phenotype. The frailty index expresses the proportion of health deficits that a person has accumulated divided by all deficits measured, whereas the phenotype defines frailty as poor performance in three of five criteria (weight loss, exhaustion, weakness, slowness, lack of activity) [7]. There is overlap between the two approaches [15].

Whilst AF is associated with an increased risk of stroke and mortality, an appropriate prescription of oral anticoagulation can reduce the risk of stroke by 64% [16, 17]. Therefore, anticoagulation is recommended for men with AF and a CHA2DS2-VASc score of 2 or greater and in women with a score of 3 or greater [18, 19]. Large randomised controlled trials have established the efficacy and safety of direct oral anticoagulant medications (DOACs) in comparison to warfarin for stroke prevention in non-valvular AF [20,21,22,23], including in people aged over 75 years [24], and they are associated with a per patient cost saving [25]. However, we lack data on the efficacy and safety of DOAC in older people with AF who are also frail [3].

Our three objectives for this study were to estimate the prevalence of frailty in people with AF; describe the association between AF, frailty, and clinical outcomes; and compare the efficacy and safety of edoxaban (a DOAC) to warfarin by frailty category.

Methods

We constructed a frailty index using data from the Effective Anticoagulation with Factor Xa Next Generation in Atrial Fibrillation–Thrombolysis in Myocardial Infarction 48 (ENGAGE AF-TIMI 48) trial [26]. The use of a frailty index is an established and validated technique for quantifying frailty using the cumulative deficit model and results in substantially better prediction of mortality and other adverse events than age alone [11, 27, 28].

Study cohort

The design and baseline characteristics of the ENGAGE AF-TIMI 48 study are described elsewhere (NCT00781391) [21, 26]. In brief, this was a randomised, double-blinded, double-dummy trial, in which two once-daily regimens of edoxaban were compared with warfarin in 21,105 patients with AF and a moderate or high risk of stroke. The trial was conducted at 1393 centres across 46 countries. Patients were enrolled from 19 November 2008 to 22 November 2010, and the median follow-up duration was 2.8 years [21]. The protocol and amendments were approved by ethics committees at each participating centre, and all participants provided written informed consent. The dataset supporting the conclusions of this article is available (subject to approval) via application at https://vivli.org. This post hoc analysis was approved by an independent review panel. Data were de-identified at source by the trial team, and patients that were deemed by the study team to be at high risk of identification (for example due to a rare medical history) were excluded from the supplied data set. This left 98.8% (n = 20,867) of the randomised participants for this analysis (Fig. 1).

Fig. 1

Consort diagram

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Participants

Patients with AF were eligible for inclusion in the ENGAGE AF-TIMI 48 study if they had documented AF of any duration within the 12 months preceding randomisation and had a CHADS2 score of 2 or higher. In this score, 1 point is allocated for each of congestive heart failure, hypertension, diabetes, and an age of 75 years or older. A prior stroke or transient ischaemic attack (TIA) is assigned 2 points. The possible range is 0 to 6, with higher scores associated with an increased stroke risk. Exclusion criteria included AF due to a reversible disorder, an estimated creatinine clearance of less than 30 ml/min, a high risk of bleeding, use of dual antiplatelet therapy, moderate-to-severe mitral stenosis, other indications for anticoagulation therapy; acute coronary syndromes, coronary revascularization, or stroke within 30 days before randomisation; and an inability to adhere to study procedures [21, 26].

Interventions

The study drugs were warfarin (dose-adjusted to achieve an international normalised ratio [INR] of 2 to 3), edoxaban 30 mg daily, or edoxaban 60 mg daily. Patients were randomised in a 1:1:1 ratio. The allocated dose of edoxaban was halved if the patient had or developed a creatinine clearance of 30–50 ml/min, a body weight of 60 kg or less, or the concomitant use of verapamil or quinidine (or dronedarone, after a protocol amendment on 22 December 2010). Standard dosing was resumed if there was no other indication for dose reduction and the verapamil, quinidine, or dronedarone was stopped.

Outcomes

The primary efficacy endpoint was the time to the first adjudicated stroke (ischaemic or haemorrhagic) or systemic embolic event. The primary safety endpoint was adjudicated major bleeding during treatment, as defined by the International Society on Thrombosis and Haemostasis [29]. The composite net clinical endpoints were stroke, systemic embolic event, major bleeding, or death; disabling stroke, life-threatening bleeding, or death; and stroke, systemic embolic event, life-threatening bleeding, or death. Given the established association between frailty and mortality [5], we report death as a separate outcome. For composite endpoints involving deaths, individuals were right censored at death in the analysis. An independent clinical endpoint committee, who were blinded to study assignment, adjudicated all deaths and suspected cerebrovascular events, systemic embolic events, myocardial infarctions, bleeding events, and hepatic events [21]. The definitions used by the clinical endpoint committee are provided in the original study protocol [26].

Blinding

To maintain blinding, each patient received two sets of study drugs—with a placebo matching warfarin for patients in the edoxaban arms or edoxaban for the patients in the warfarin arms. The INR was measured at least monthly, with sham results generated in the edoxaban groups.

Frailty

We defined frailty using the cumulative deficit model, which identifies deficits in health (such as symptoms, signs, diseases, disabilities, or abnormalities in clinical investigations) on the basis that the more deficits a person has, the more likely that the person is frail [30]. The cumulative deficit model enables calculation of a frailty index as an equally weighted proportion of the number of deficits present in an individual to the total possible. For this study, we constructed a frailty index using the available trial data, calculated at the time of study entry. In line with the established guidance for constructing a frailty index, candidate health deficit variables for inclusion were identified on the basis that they were associated with health status, their prevalence generally increases with age, they do not reach saturation too early (over 80% prevalence before the age of 80), and they cover a range of body systems [31]. Data needed to be available for at least 70% of items for inclusion [32]. The 40 items included in the construction of the frailty index are detailed in Additional file 1: Table S1. The presence or absence of each variable was ascertained from data collected by the trial investigators as part of their protocol-specified assessment, which took place within 30 days of study randomisation [33]. Participants were categorised based upon the frailty index into fit (0 to < 0.12), living with pre-frailty (≥ 0.12 to < 0.24), mild-moderate (≥ 0.24 to < 0.36), and severe frailty (≥ 0.36 to 1.0), based upon thresholds that are commonly used in the literature [11, 34].

Statistical methods

Baseline characteristics are reported for the frailty groups and by treatment allocation. Continuous variables are presented as medians with interquartile range, and categorical variables as counts and proportions. Event rates for each of the primary and secondary (composite) outcomes were calculated as the number of events per 100 person-years and reported by frailty category and treatment arm.

Cox proportional hazard models were used to (1) test whether each regimen of edoxaban was non-inferior to warfarin for each primary and secondary (composite) outcomes, stratified by frailty category, and (2) quantify the association between frailty category and the primary and secondary (composite) outcomes, with the treatment arm included as an interaction term. The proportional hazards assumption was assessed using Schoenfeld residuals tests. Hazard ratios with 95% confidence intervals (CIs) were reported for each. As the trial participants were randomised by treatment allocation, but not frailty, comparisons by frailty were adjusted for age, sex, race, and region. These limited adjustments were made to preserve the association between frailty and outcomes. Finally, the impact of an increase of 0.1 in frailty index on each clinical outcome for the complete analytical cohort was calculated. Hazard ratios were adjusted for the treatment group and reported alongside estimates further adjusted for age, sex, race, and region, in the whole cohort. A sensitivity analysis was completed for the association between frailty and the clinical outcomes, where frailty index items were removed if they were related to bleeding (history of non-intracranial bleeding and peptic ulcer). Data were analysed in Stata 15.1 and R version 3.4.1.

Results

Participants

We include 20,867 participants in the analysis (38.1% women [n = 7940]; 86.8% 60 years or older [n = 18,119]; 25.5% with paroxysmal AF [n = 5311]; Fig. 1, Table 1). Overall, 21.4% (n = 4459) of participants were categorised as fit; 59.1% (n = 12,326) were pre-frail; 17.8% (n = 3722) had mild-moderate frailty; and 1.7% (n = 360) had severe frailty (Additional file 1: Fig. S1). The predicted stroke risk was higher with increased frailty (mean CHADS2 score: fit 2.39, pre-frail 2.80, mild-moderate frailty 3.37, severe 4.03).

Table 1 Baseline characteristics of participants by frailty category
Full size table

There was a similar number of participants in each treatment arm (warfarin 33.3% [n = 6957]; edoxaban 30 mg 33.3% [n = 6956]; edoxaban 60 mg 33.3% [n = 6954]), and the distribution of frailty category was comparable between treatment arms (Fig. 1). The characteristics of patients in each treatment group, stratified by frailty, are reported in Additional file 1: Table S2.

Primary outcomes

Across the three treatment arms, 997 patients experienced stroke or systemic embolism (rate per 100 person-years: warfarin 1.73 [95% CI 1.54–1.92]; edoxaban 30 mg 1.95 [1.76–2.15]; edoxaban 60 mg 1.47 [1.30–1.64]; Table 2). There was no difference in stroke or systemic embolism between the treatment arms (Additional file 1: Table S3), including when stratified by frailty category (Table 3). Across the treatment arms, in comparison to the fit group, the average adjusted risk of stroke or systemic embolism over the follow-up period was 84% higher in the group living with mild-moderate frailty and more than double in those living with severe frailty (Table 4). On average over the follow-up period, for each increase of 0.1 in the frailty index (four additional health deficits), the risk of stroke or systemic embolism increased by 37% (adjusted HR 1.37, 1.19–1.58).

Table 2 Numbers and rates of outcome events
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Table 3 The association between oral anticoagulation and outcomes, stratified by frailty category
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Table 4 The association between frailty category and clinical outcomes
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Overall, 1185 participants experienced major bleeding during treatment (rate per 100 person-years: warfarin 2.76, 95% CI 2.52–3.00; edoxaban 30 mg 1.28, 1.12–1.44; edoxaban 60 mg 2.17, 1.96–2.38; Table 2). On average over the follow-up period, bleeding events were 53% lower in patients taking edoxaban 30 mg compared to warfarin (HR 0.47, 95% CI 0.40–0.54) and 21% lower in those taking edoxaban 60 mg (HR 0.79, 0.69–0.89, Additional file 1: Table S3). When stratified by frailty category, edoxaban 30 mg was associated with a reduction in major bleeding compared with warfarin in all but those with severe frailty, and edoxaban 60 mg with a reduction in major bleeding in the pre-frail and mild-moderate frailty groups only (Table 3). Across the treatment arms, the adjusted risk of major bleeding increased with the frailty category, such that for each increase of 0.1 in the frailty index (four additional health deficits), the risk of major bleeding increased by 42% on average over the follow-up period (adjusted HR 1.42, 1.27–1.59).

Composite net clinical endpoints

Overall, 4030 participants experienced stroke, systemic embolic event, major bleeding, or death (rate per 100 person-years: warfarin 7.90, 95% CI 7.50–8.31; edoxaban 30 mg 6.58, 6.22–6.95; edoxaban 60 mg 7.06, 6.68–7.44; Table 2). Disabling stroke, life-threatening bleeding, or death affected 2699 participants (rates: warfarin 5.07, 4.75–5.39; edoxaban 30 mg 4.26, 3.97–4.55; edoxaban 60 mg 4.52, 4.22–4.81; Table 2). Stroke, systemic embolic event, life-threatening bleeding, or death affected 3098 participants (rates: warfarin 5.80, 5.45–6.14; edoxaban 30 mg 5.16, 4.84–5.48; edoxaban 60 mg 5.12, 4.80–5.43; Table 2).

Compared with warfarin, there was a significant reduction for each of the three composite outcomes associated with the use of edoxaban at both 30-mg and 60-mg dosages (Additional file 1: Table S3). When stratified by frailty category, there was no difference in each of the three composite outcomes according to the treatment arm for those in the fit category (Table 3). In those living with pre-frailty, a reduction in all three composite outcomes was associated with edoxaban 60 mg compared with warfarin. For edoxaban 30 mg, the risk was reduced in composite outcome (1) stroke, systemic embolic event, major bleeding, or death and (2) disabling stroke, life-threatening bleeding, or death—but not for the composite outcome (3) stroke, systemic embolic event, life-threatening bleeding, or death. For those living with mild-moderate frailty, there was a reduction in (1) and (2) with the 30-mg dose, and no difference in the composite outcomes between the use of edoxaban 60 mg and warfarin. Finally, in those with severe frailty, there was a reduction in (2) with edoxaban 60 mg compared to warfarin, and no difference in the composite outcomes between edoxaban 30 mg and warfarin, and for the other composite outcomes for the 60-mg dosage (Table 2).

When modelling frailty index on a continuous scale, there was a significantly increased risk of all three composite outcomes with increasing frailty across all three treatment arms. For each increase of 0.1 in the frailty index (four additional health deficits), the adjusted risks on average over the follow-up period of (1) stroke, systemic embolic event, major bleeding, or death increased by 59% (HR 1.59, 1.48–1.69); (2) disabling stroke, life-threatening bleeding, or death by 72% (1.72, 1.59–1.87); and (3) stroke, systemic embolic event, life-threatening bleeding, or death by 67% (1.67, 1.55–1.80). The overall findings were robust to a sensitivity analysis in which the frailty index was modified to remove factors specifically associated with bleeding risk (Additional file 1: Table S4).

Mortality

There was a stepwise association between frailty category and mortality, whereby patients with severe frailty had a hazard ratio for mortality of 4.97 (3.42–7.23) compared to the fit group (Table 4). Mortality accounted for a greater proportion of the composite endpoints with increasing frailty category (Table 2).

Discussion

In this analysis of a large international clinical trial, we have shown that edoxaban is non-inferior to warfarin across the frailty spectrum in stroke prevention. Bleeding events were reduced in patients who received edoxaban except in those living with severe frailty—where standardised bleeding event rates were not statistically significantly different from warfarin. We found that just one in five trial participants had frailty and that frailty was associated with worse clinical outcomes, regardless of treatment arm allocation.

The key finding of the ENGAGE AF-TIMI 48 trial was that edoxaban was associated with lower rates of bleeding and death from cardiovascular causes compared with warfarin, with similar efficacy in stroke and systemic embolism prophylaxis. In our stratified analyses, however, these findings were not upheld for every frailty category. Instead, it appeared that the effect was driven by the pre-frail group, which was the most prevalent frailty category in the trial population. This may relate to a lack of statistical power, particularly as the trend in every subgroup is consistent with the overall trial finding. Even so, we cannot conclude with certainty from this analysis that the overall trial findings are applicable to patients living with severe frailty. Here, those patients were under-represented, even though they are a group at high risk of stroke, and in whom AF is common [3, 4].

The distribution of the frailty scores in this trial is striking. One in five participants was frail, and just one in 50 had severe frailty. This is in contrast with the primary care population of older people with AF, in which over half live with moderate or severe frailty [4]. It is known that health problems tend to accumulate with age and therefore frailty is generally progressive [35], with an average rate of deficit accumulation in community-dwelling older people of 3% per year [36]. With population ageing, the burden of frailty is likely to grow substantially [37], amplifying the need for robust trial data that is specific to people with frailty who are at particular risk of treatment-related harm. The perception of a gap between the representation of people with frailty in trials and the clinical population may explain, at least in part, the relatively low 'real-world' prescription rates of oral anticoagulation for eligible patients [38,39,40] and may reflect clinicians' fear of causing iatrogenic harm, particularly in people with frailty [3]. This must be considered alongside our finding that death is more common in patients with AF and also frailty—which is well known in a general population [10,11,12,13,14].

We have demonstrated that frailty is associated with worse clinical outcomes regardless of treatment arm allocation. The risk of every trial endpoint was at least doubled for patients with severe frailty compared to the fit group, with the appearance of a 'dose-response relationship' despite therapy. This is a population with a high baseline risk of cardiovascular events and death, and a high residual risk remains, despite therapy. This risk is likely to be multifactorial, including non-embolic stroke and death from non-cardiovascular causes that may not be modifiable in the context of advancing multi-organ disease. That the risk of major bleeding on treatment was substantially higher with increasing frailty category may represent a target for improvement. Modifiable bleeding risk factors should be optimised—including a review of concomitant antiplatelet and non-steroidal anti-inflammatory medications [19], as well as a renewed focus on DOAC dosing, which may be complex and is commonly incorrect [41].

A recent randomised controlled trial found that in older Japanese patients, a daily 15-mg dose of edoxaban was superior to placebo in preventing stroke or systemic embolism, without a significantly higher incidence of major bleeding than placebo [42]. These findings are important, but we know that there is a graded degree of risk amongst older people of the same age [4, 7, 10, 30], and there remains a notable lack of generalisable data concerning the outcomes associated with anticoagulation for patients with more advanced frailty [3]. There are many reasons why older people are historically under-represented in clinical trials, including the presence of co-morbidities, communication issues, and physical immobility that limit opportunities for participation [43]. Yet, in view of a high baseline risk of both stroke and iatrogenic harm, there is a strong argument for frailty-specific population randomised trials in this area. In lieu of specific randomised evidence to quantify efficacy and safety in older people with severe frailty, future work modelling outcomes using a combination of epidemiological and trial data may yield interesting insights [44, 45].

This study has strengths, which include the ENGAGE AF-TIMI 48 dataset, in which there were few missing data, a large sample size, and a long follow-up duration [21, 26]. To our knowledge, this study is the first to report the outcomes of such a trial by frailty [3]. As the recruitment of patients with frailty into clinical trials is challenging, these analyses are necessary and important in order to guide clinicians and individualise therapy [46]. Frailty was identified using a conceptually robust and reproducible measure [31], that is increasingly used in understanding the relationship between age and outcomes in clinical trials [10], and allows the risk of adverse outcomes to be defined more precisely than a phenotypic approach [15]. We adjusted the associations between frailty and outcomes for potential confounders. However, we recognise the limitations of our work. In particular, the trial exclusion criteria mean that patients with more severe frailty were excluded, for example patients with a life expectancy of less than 12 months or who were unable to attend for trial visits [26]. This means that the results are not generalisable to the whole population of older people with frailty. Secondly, whilst we did not have access to the complete dataset, the rates of the outcomes were similar to those in the original trial [26]. Thirdly, as the trial was not designed for the analyses that we have undertaken, the analyses stratified by frailty category are likely to be underpowered. Fourthly, data were not available to evaluate phenotypically defined frailty in this dataset. Finally, the study was conducted in the era before specific reversal agents, which may impact upon bleeding severity and associated mortality in future clinical practice.

Conclusion

Patients with AF taking anticoagulation with warfarin or edoxaban are at substantially higher risk of stroke or systemic embolism, major bleeding during treatment, and death if they also have frailty. We showed important differences in the overall risk of adverse outcomes increasing with frailty, and efficacy was similar between warfarin and edoxaban. Whilst a reduction in bleeding was associated with edoxaban overall, this was not substantiated across all frailty categories, and people with more advanced frailty made up a small proportion of the overall trial population. This highlights the need for high-quality, frailty-specific population randomised controlled trials to guide therapy in this vulnerable population.

Availability of data and materials

The dataset supporting the conclusions of this article is available (subject to approval) via application at https://vivli.org.

Abbreviations

AF:

Atrial fibrillation

CHADS2 score:

One point for the history of congestive heart failure, hypertension, age ≥ 75 years, and diabetes; two points for stroke or TIA

CHA2DS2-VASc score:

One point for the history of congestive heart failure, hypertension, diabetes, vascular disease history (prior MI, peripheral artery disease, or aortic plaque), age 65–74 years, and female sex; two points for age ≥ 75, history of stroke, or TIA

CI:

Confidence interval

Cr:

Creatinine

DOAC:

Direct oral anticoagulant

ENGAGE AF-TIMI 48 :

Effective Anticoagulation with Factor Xa Next Generation in Atrial Fibrillation–Thrombolysis in Myocardial Infarction 48

INR:

International normalised ratio

SD:

Standard deviation

TIA:

Transient ischaemic attack

VKA:

Vitamin K antagonist

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Unusual onset of thyroid associated orbitopathy during pregnancy

Case report
Open Access
Published: 15 December 2020
Unusual onset of thyroid associated orbitopathy during pregnancy: case report and review of literature
Janos K. Aranyosi, Tamas Deli, Annamaria Erdei, Geza Toth, Attila Jakab, Mariann Fodor, Endre V. Nagy & Bernadett Ujhelyi
BMC Endocrine Disorders volume 20, Article number: 183 (2020) Cite this article

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Abstract
Background
Thyroid associated orbitopathy (TAO) is the most common extrathyroidal complication of Graves' disease. The disease course ranges from mild, where symptomatic therapy is sufficient, to severe, where high dose steroid administration or orbital decompression surgery is required. Women of their reproductive age are more likely to be affected. Although pregnancy is a state of enhanced immune tolerance, TAO may develop or worsen in 0.2–0.4% of pregnant women.

Case presentation
We present the case of a 19-year-old woman who has developed hyperthyroidism and progressive TAO during the second trimester of her third pregnancy, which has improved postpartum. The possible mechanisms and the importance of follow up in pregnancy is discussed.

Conclusions
Expectant mothers with Graves' disease require follow up of eye signs throughout pregnancy, preferably in the setting of a thyroid-eye clinic.

Peer Review reports

Background
Graves' disease (GD) and Hashimoto's thyroiditis (HT) are autoimmune disorders, that may affect around 2% of the population [1]. GD occurs more frequently in women, smokers, patients suffering from other autoimmune diseases and those with a positive family history for thyroid autoimmunity [2]. GD is the most common cause of hyperthyroidism in women of reproductive age. It occurs before and during pregnancy in 0.4–1% and 0.2–0.4% of the cases, respectively [3, 4]. According to a recent review by Chin et al. in approximately 40% of the cases GD is accompanied by thyroid associated orbitopathy (TAO) [5]. In 5%, deterioration of visual acuity may occur [6]. In mild cases local therapy such as artificial tears, ointments, sunglasses and higher pillows at night are sufficient. Severe cases require systemic immunosuppressive therapy, usually with high dose corticosteroids [7]. Additional options are retrobulbar irradiation and orbital wall decompression surgery [8]. During pregnancy the therapeutic options are limited.

The majority of autoimmune diseases tend to improve during gestation due to the state of enhanced immune tolerance. Thyroid autoimmune diseases, multiple sclerosis and rheumatoid arthritis show improvement during pregnancy [9, 10]. There are a few exceptions; SLE and type 1 diabetes deteriorate [11].

In GD, humoral immune response predominates. Stimulating antibodies against the TSH receptor (TRAb) result in the clinical manifestations of the disease, including hyperthyroidism, goiter, orbitopathy and dermopathy [12]. The development or exacerbation of GD in pregnancy is rare and spontaneous improvement in the second trimester is typical. This is accompanied by the decrease of stimulating TRAbs [13, 14]. Relapse is often observed between 4 and 8 months after delivery. In this period, the enhanced immune tolerance ceases, resulting in elevated levels of TRAbs [14].

Here we present a case of GD with TAO, which developed in the second trimester of pregnancy.

Case presentation
A 19-year-old pregnant woman has been referred to our department during her 3rd pregnancy for GD and new-onset TAO. Hyperthyroidism was diagnosed by her primary care physician at week 20 of pregnancy. Her laboratory results were: TSH 0.01 mU/L, FT4: 78,4 pmol/L (reference range: 12–22 pmol/L), FT3: 37.4 pmol/L (reference range: 3.1–6.8 pmol/L). For unknown reasons, she showed up three months later, at week 33 of pregnancy, with untreated hyperthyroidism. She did not report any other disease. She has had no history of thyroid disease and no pre-pregnancy TSH values were available. The two previous pregnancies conceived naturally and were completed by cesarean section due to cephalopelvic disproportion. She smoked 20 cigarettes daily during pregnancy and failed to quit smoking in spite of repeated counseling.

On presentation at week 33 her main complaints were proptosis and limited movement of the right eye with accompanying pain. She recalled that her first symptom, the proptosis appeared around week 14 of gestation. On admission TSH and thyroid hormone levels were in the hyperthyroid range (Table 1). Her TRAb level was 2.4 U/L (reference range:< 1 U/L), while the anti-thyroglobulin antibody level was 1324.0 IU/ml (reference range: < 60 IU/ml.). In spite of current recommendations [15] an initial dose of metimazol 50 mg/day has been chosen; severe type T3 hyperthyriodism was considered to carry high risk of preterm delivery, while there was no fetal risk of thiamazole in the 3rd trimester. After 3 days, the dose of thiamazole was reduced to 30 mg per day. Examination showed marked exophthalmos on the right side with restricted and painful eye movement, decreased best corrected visual acuity (20/32) and eyelid edema. Proptosis was 28 and 21 mm at the right and left sides, respectively by Hertel exophthalmometry at 90 mm (regional normal < 20 mm). The disease was graded as severe on the EUGOGO scale [16]. Clinical Activity Score (CAS) was 6/7 and 0/7 on the right and left sides, respectively.

Table 1 Hormone levels and thiamazole doses
Full size table
The fetus showed no signs of intrauterine growth restriction, no tachycardia or goiter and the growth rate was satisfactory on follow up according to the ultrasonography. From week 34, the therapeutic dose of thiamazole was reduced to two times 15 mg daily (Table 1). Eye examination on week 38 showed improvement in visual acuity, CAS and proptosis. (Table 2), although retrobulbar pain, pain on eye movement, eyelid edema and conjunctival redness remained. Because the patient did not develop sight-threatening TAO, the thyroid-eye clinic team decided not to initiate high-dose corticosteroid therapy.

Table 2 Ophthalmologic examinations
Full size table
A healthy female baby was delivered through cesarean section on week 39. Both TAO and cephalopelvic disproportion were contraindications of vaginal delivery. The newborn did not show clinical signs of thyroid dysfunction, and day 3 TSH was in the reference newborn range. The mother's thyroid hormone levels started to rise after delivery; thiamazole dose was modified accordingly, supplemented with bisoprolol. Her eye complaints substantially improved the next day after the cesarean section, CAS declined, and visual acuity returned to normal (Table 2). Proptosis, eyelid and conjunctival redness and swelling of the eyelid and caruncula were still present on day 3 postpartum (Fig. 1). MRI examination was to be performed, however, the patient declined it. For the relapsing Graves' disease and orbital involvement, total thyroidectomy was scheduled; later she declined and she and her baby were lost for follow up.

Fig. 1
figure1
The patient's eyes on day 3 postpartum. Exophthalmos on the right side was still present. Visual acuity returned to 20/20

Full size image
Discussion and conclusions
Graves' disease is caused by autoantibodies, which bind to the thyrotropin receptor on thyroid follicular cells and orbital fibroblasts, causing the overproduction of thyroid hormones [17] and in 40% of these patients TAO, respectively [6]. The autoimmune inflammation of the retrobulbar connective tissue is characterized by the presence of lymphocytes and macrophages and the overproduction of connective tissue matrix by fibroblasts [18, 19].

During normal pregnancy, several physiological changes occur [20]. Both red blood cell mass and plasma volume increase in pregnancy; as the latter increase is more marked, physiological haemodilution is present. Heart rate and stroke volume increase while vascular resistance falls. Glucose tolerance decreases, as does biliary excretion. Estrogen and progesterone levels rise dramatically, estrogen levels being 100-times higher than in the menstrual cycle [20]. The number of natural killer cells (NK) might be normal; however their cytolytic activity is decreased [21]. The number of circulating plasma cells and B-cells remains normal, as do antibody response and antibody production [22]. Although there is no significant change in the number of circulating T-lymphocytes during pregnancy, a slight decline may occur in the proportion of CD4+ cells resulting in suppressed immune activity [23]. Regulatory CD4+ CD25 + T cells, or Treg cells are responsible for regulating Th1-type and Th2-type activities. Th1-type and Th2-type immune processes are involved in cellular and humoral immunity, respectively [24]. In early pregnancy the number of Treg cells increases rapidly, reaching the peak in the second trimester [25]. They can suppress both Th1-type and Th2-type reactivity against fetal alloantigens. Th1 clones are more sensitive to the Treg effect, which leads to the predominance of Th2 clones over Th1 cellular immune response; the cytokine balance is driven away from the adverse effects of Th1 cell activity which could lead to abortion [26]. Therefore, the proper balance of Th1/Th2 cell activities has an important role in maintaining pregnancy. A clear decline in the number of Treg cells is observed in the weeks before delivery. This restoration of the non-pregnant or pre-pregnancy state may facilitate the exacerbation of autoimmune diseases after delivery [27, 28].

Pregnancy has a complex effect on the course of autoimmune disorders. The majority of autoimmune diseases tend to improve during pregnancy, except for SLE and type 1 diabetes, which usually worsen [9, 11]. Stable Graves' disease on thiamazole may transiently worsen in the first trimester due to the thyroid stimulating effect of the hCG rise [29]. There is an improvement due to physiological immune tolerance in the second trimester. A relapse in the postpartum period, when the immune function returns to a normal, is common [30]. Therefore, improvement in the disease activity of both GD and TAO can be anticipated during pregnancy. While this is true for GD, unfortunately, less is known about the course of TAO [19, 31]; GD and TAO might follow separate courses during pregnancy. In one study, 5 out of 9 women with mild to moderate eye symptoms developed proptosis during pregnancy; on the other hand, 70% of patients with pre-existing disease had either improvement or no change in their eye signs and 30% experienced worsening in the postpartum period [32].

In the present case, a relapse of Graves' disease was diagnosed during gestation. TAO appeared around the 14th week of pregnancy whereas she had no similar complaints during her two previous pregnancies. Her orbital condition was severe on presentation. It was not known if the reduced visual acuity was a new complaint. For this reason, both visual acuity and critical fusion frequency were tested on alternate days. We considered the orbitopathy moderate to severe [7], definitely not sight threatening; VA was 20/32. According to the EUGOGO guidelines [7], we decided to restore euthyroidism first and urged the patient to quit smoking. The latter measure is known to be nearly as effective as corticosteroids. As VA improved and signs reduced, there was no need to initiate immunosuppressive treatment.

We believe that the major contributors to TAO development and worsening during pregnancy have been the hypervolemia-related physiological changes and their reflections in the orbital tissue. A minor increase of orbital tissue volume can result in the worsening of TAO, as any volume excess in the orbital cone will lead to elevated cone pressure, further stretching of the rectus muscles, and decreased venous drainage into the cavernous sinus [33]. The usual rapid volume redistribution after delivery may explain the immediate improvement of TAO. It is not entirely clear why some of the TAO patients develop asymmetric disease; at presentation, other causes of unilateral exophthalmos have to be ruled out [34]. We [35] and others found that the orbital process is unequivocally two-sided by imaging, even in those cases where one side appears completely spared. MRI was planned but was postponed until after delivery in accordance with the practice guidelines collaboratively developed by the American College of Radiology (ACR) and the Society for Pediatric Radiology (SPR) for any trimester in pregnancy [36]. The patient failed to show up for imaging.

Further, the pregnant patient smoked 20 cigarettes daily. Although there were no data on the number of cigarettes smoked during her previous two pregnancies, the increasing amount of cigarettes per day throughout the years may account for the appearance of TAO. Furthermore, this case is unusual, because Graves' hyperthyroidism did not limit itself during pregnancy; persisting thyroid dysfunction may have been a contributor to the worsening of TAO.

The limitation of our case report is that we could perform neither the MRI examination nor the follow-up visit due to low compliance of the patient. Her low socioeconomic status may account for both the disappearance from medical care, as well as smoking throughout pregnancy.

Both smoking and hypervolemia may have contributed to the development of TAO. The deterioration in the 3rd trimester may have most probably been volume-related as the eye signs rapidly regressed after delivery, while she maintained the same smoking intensity. Further improvement of the eye signs was confirmed by the patient at the single phone call she returned. Expectant mothers with Graves' disease require follow up of eye signs throughout pregnancy, preferably in the setting of a thyroid-eye clinic.

Availability of data and materials
The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.

Abbreviations
TAO:
Thyroid associated orbitopathy

GD:
Graves' disease

HT:
Hashimoto's thyroiditis

TRAb:
TSH receptor autoantibodies

CAS:
Clinical Activity Score

NK:
Natural killer cells

VA:
Visual acuity

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Medicine by Alexandros G. Sfakianakis,Anapafseos 5 Agios Nikolaos 72100 Crete Greece,00302841026182,00306932607174,alsfakia@gmail.com,
Telephone consultation 11855 int 1193,

Prevention of postoperative bleeding after complex pediatric cardiac surgery by early administration of fibrinogen, prothrombin complex and platelets

Research article
Open Access
Published: 18 December 2020
Prevention of postoperative bleeding after complex pediatric cardiac surgery by early administration of fibrinogen, prothrombin complex and platelets: a prospective observational study
Nils Dennhardt, Robert Sümpelmann, Alexander Horke, Oliver Keil, Katja Nickel, Sebastian Heiderich, Dietmar Boethig & Christiane E. Beck
BMC Anesthesiology volume 20, Article number: 302 (2020) Cite this article

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Abstract
Background
Postoperative bleeding is a major problem in children undergoing complex pediatric cardiac surgery. The primary aim of this prospective observational study was to evaluate the effect of an institutional approach consisting of early preventive fibrinogen, prothrombin complex and platelets administration on coagulation parameters and postoperative bleeding in children. The secondary aim was to study the rate of re-intervention and postoperative transfusion, the occurrence of thrombosis, length of mechanical ventilation, ICU stay and mortality.

Methods
In fifty children (age 0–6 years) with one or more predefined risk factors for bleeding after cardiopulmonary bypass (CPB), thrombelastography (TEG) and standard coagulation parameters were measured at baseline (T1), after CPB and reversal of heparin (T2), at sternal closure (T3) and after 12 h in the ICU (T4). Clinical bleeding was evaluated by the surgeon at T2 and T3 using a numeric rating scale (NRS, 0–10).

Results
After CPB and early administration of fibrinogen, prothrombin complex and platelets, the clinical bleeding evaluation score decreased from a mean value of 6.2 ± 1.9 (NRS) at T2 to a mean value of 2.1 ± 0.8 at T3 (NRS; P <  0.001). Reaction time (R), kinetic time (K), maximum amplitude (MA) and maximum amplitude of fibrinogen (MA-fib) improved significantly (P <  0.001 for all), and MA-fib correlated significantly with the clinical bleeding evaluation (r = 0.70, P <  0.001). The administered total amount of fibrinogen (mg kg− 1) correlated significantly with weight (r = − 0.42, P = 0.002), priming volume as percentage of estimated blood volume (r = 0.30, P = 0.034), minimum CPB temperature (r = − 0.30, P = 0.033) and the change in clinical bleeding evaluation from T2 to T3 (r = 0.71, P <  0.001). The incidence of postoperative bleeding (> 10% of estimated blood volume) was 8%. No child required a surgical re-intervention, and no cases of thrombosis were observed. Hospital mortality was 0%.

Conclusion
In this observational study of children with an increased risk of bleeding after CPB, an early preventive therapy with fibrinogen, prothrombin complex and platelets guided by clinical bleeding evaluation and TEG reduced bleeding and improved TEG and standard coagulation parameters significantly, with no occurrence of thrombosis or need for re-operation.

Trial registration
German Clinical Trials Register DRKS00018109 (retrospectively registered 27th August 2019).

Peer Review reports

Background
Postoperative bleeding is a major problem in children with congenital heart disease undergoing complex pediatric cardiac surgery with cardiopulmonary bypass (CPB) and results in significant postoperative morbidity and mortality [1, 2]. Risk factors associated with a higher incidence of bleeding are an age of less than 1 year, hypothermia on CPB, longer CBP duration and re-sternotomy [3]. For the prevention of massive bleeding, blood products and coagulation factor concentrates can be used early after CPB [4, 5]. In our institution, fibrinogen, prothrombin complex concentrate and platelets are used routinely in children with an increased bleeding risk until sufficient hemostasis is achieved and surgical closure of the thorax is possible. More than ten years of experience have shown this approach to be safe and effective, but no objective evaluation has been performed yet. Therefore, we conducted a prospective clinical observational study to investigate the impact of our institutional approach on children with increased risk of postoperative bleeding. The primary aim was to evaluate the effect on standard coagulation parameters, thrombelastography and postoperative bleeding. The secondary aim was to study the rate of re-intervention and postoperative transfusion, the occurrence of thrombosis, length of mechanical ventilation, ICU stay and mortality.

Methods
Patients
This prospective observational study was conducted according to the standards set forth by the Declaration of Helsinki and Good Clinical Practice guidelines. Following the local ethics committee's approval (Ethics Committee of Hanover Medical School, Germany, Chairperson Prof. Dr. H. D. Troeger, No. 7349 dated February 2, 2017), 50 children ranging from 0 to 6 years of age scheduled for cardiac surgery with CPB and one or more risk factors for bleeding were included (Fig. 1). The risk factors were predefined as an age of less than 1 year, hypothermia on CPB < 32 °C, expected CPB duration > 90 min, re-sternotomy or extensive aortic suture lines. Children with pre-existing coagulation disorders or on anticoagulant or antiplatelet therapy were excluded. The study was conducted from April 2017 to November 2018 at the Clinic for Anesthesiology and Intensive Care Medicine, Hanover Medical School, Germany, and all operations were performed by the same team of surgeons.

Fig. 1
figure1
Study flow chart

Full size image
Intraoperative management
Anesthesia was induced by injection of 0.5 mg kg− 1 etomidate, 0.5 μg kg− 1 sufentanil and 0.5 mg kg− 1 atracurium and maintained by sufentanil 1 μg kg− 1 h− 1 and sevoflurane (on CPB administered via oxygenator).

CPB was performed with the heart-lung machine LivaNova S5 (LivaNova PLC, London, UK) and the oxygenator system TerumoFX05 (Terumo Corporation, Tokyo, Japan). The system was prepared in a standardized fashion: The circuit was primed with a bicarbonate-buffered hemofiltration solution (BB-HS; Duosol, B. Braun, Melsungen, Germany), 2 mL kg− 1 mannitol, 150 IU kg− 1 of heparin and 20 mL kg− 1 gelatin. In infants with a body weight below 5 kg, 10 mL kg− 1 albumin 20% was used instead of gelatin. Packed red blood cells were added if necessary to achieve hemoglobin levels of 8–10 g dL− 1. According to patient's weight, the total priming volume fluctuated between 180 and 450 ml. To achieve a physiological composition, priming volume was hemofiltered before CPB using a polysulfone hemofilter (ME HF0S 0020, Medos AG, Stolberg, Germany) by ten minutes circulation until approximately 1000 mL of ultrafiltrate were restored by BB-HS [6]. During the last 30 min of CPB, 20–30 mL kg− 1 fresh frozen plasma was added, and a higher amount of fluid was removed by hemofiltration. Target pump flow was 2.7 L min− 1 m− 2 for children and 3.0 L min− 1 m− 2 for infants below one year of age. Target mean arterial pressure was guided by near-infrared spectroscopy (NIRS) and continuously measured central venous oxygen saturation in the venous line of the bypass. Before CPB, a heparin bolus of 400 IU kg− 1 was given to achieve anticoagulation. During CPB, activated clotting time (ACT) was maintained longer than 400 s by adding additional heparin if necessary. Tranexamic acid was administered at 10 mg kg− 1 h− 1. At the end of CPB, the administered heparin was reversed by protamine starting at a ratio of 0.8 until the ACT had returned to < 130 s.

After CPB weaning, heparin reversal and clinical bleeding evaluation, the hemostatic therapy was started with 50 mg kg− 1 human fibrinogen (Haemocomplettan®, CSL Behring GmbH, Marburg, Germany), 50 IU kg− 1 human prothrombin complex (Beriplex®, CSL Behring GmbH, Marburg, Germany) and 20 mL kg− 1 platelets. Repeat doses were guided by clinical bleeding evaluation and TEG as follows: In case of MA-fib < 15 mm, fibrinogen was added; in case of R > 9.5 min, prothrombin complex was added; and in case of MA < 52 mm and normal MA-fib (> 15 mm), platelets were added until the bleeding situation improved clinically significant and closure of the thorax was possible.

Data collection
Results of blood gas analysis, hematologic (hemoglobin, hematocrit, platelets), coagulation standard (Quick value of prothrombin time (Quick), activated partial thromboplastin time (aPTT), activated clotting time (ACT), fibrinogen (Clauss method), antithrombin III, factor II, factor V and TEG parameters (reaction time (R), kinetic time (K), angle, maximum amplitude (MA), functional fibrinogen, maximum amplitude of functional fibrinogen (MA-fib), fibrinolysis at 30 min after maximum amplitude (LY30)) were collected at the following points in time: at baseline before skin incision (T1); after CPB and reversal of heparin by protamine before administration of coagulation factors or blood products (T2); at sternal closure (T3); and after 12 h in the ICU (T4). For the TEG analysis, the TEG 6 s analyzer (Haemonetics, Braintree, Massachusetts, USA) was used. At T2 and T3, the operating surgeon was asked to evaluate the bleeding on a numeric rating scale from 0 to 10 (NRS; 0 = absolutely dry, no signs of any bleeding at all; 10 = massive bleeding with no signs of coagulation). The administered coagulation factors and blood products were documented. Intraoperative data included CPB time, cross-clamp time, duration of deep hypothermic circulatory arrest (if used) and the lowest temperature during CPB. Postoperative data included chest drainage output within the first six postoperative hours, rate of re-intervention and postoperative transfusion, the occurrence of thrombosis, length of mechanical ventilation, ICU stay and mortality. Significant postoperative bleeding was defined as a blood loss of more than 10% of the child's estimated blood volume within the first six postoperative hours.

Statistics
Data were recorded in an Excel database, analyzed using MS Excel (Excel 2010; Microsoft, Seattle, USA) and GraphPad Prism (Prism 7; Graph Pad Software Inc., San Diego, USA) software tools, and presented as mean values plus standard deviation (range) or as median (range). Spearman correlation, regression analysis and independent-samples Mann-Whitney-U tests were performed with a pre-defined significance level of α = 0.05.

Results
A total of 50 children were included. Surgical procedures are summarized in Table 1. Demographic, intra- and postoperative data are summarized in Table 2.

Table 1 Surgical procedure type (n = 50)
Full size table
Table 2 Demographic, intra-, and postoperative data (n = 50). Data are presented as mean ± standard deviation (range) or number (percentage)
Full size table
Besides hemoglobin concentration, there were no significant differences between cyanotic and non-cyanotic children in measured hematologic, coagulation standard or TEG parameters at baseline (T1). After CPB and administration of protamine (T2), hemoglobin, hematocrit, platelets, Quick, fibrinogen, AT III, factor II, angle, MA, MA-fib and LY30 were significantly reduced, and R and K were significantly extended, as compared to the baseline values (T1) (P <  0.001 for all). ACT, aPTT and factor V did not differ significantly (Table 3). At this point in time (T2), the surgeon evaluated clinical bleeding at a mean value of 6.2 ± 1.9 on a numeric rating scale, and the administration of fibrinogen (mean total amount 108 ± 56 mg kg− 1), prothrombin complex concentrate (mean total amount 70 ± 26 IU kg− 1), platelets (mean total amount 22 ± 14 mL kg− 1) and red blood cells (mean total amount 18.9 ± 18 mL kg− 1) was started. In combination with surgical hemostasis, the results of the clinical bleeding evaluation score reduced significantly to a mean of 2.1 ± 0.8 (P <  0.001). At sternal closure (T3), platelets, Quick, fibrinogen, factor II, angle, MA and MA-fib had significantly increased, and R and K had significantly decreased (P <  0.001 for all, Table 3).

Table 3 Hematologic, coagulation standard and TEG parameters, and clinical bleeding as assessed by surgeon at baseline (T1), after bypass and administration of protamine (T2), at sternal closure (T3), and in ICU after 12 h (T4). Data are presented as median (range)
Full size table
Results of TEG parameters and clinical bleeding evaluation are shown in Fig. 2. MA-fib correlated significantly with the clinical bleeding evaluation (r = 0.70, P < 0.001). The administered total amount of fibrinogen (mg kg− 1) correlated significantly with age (r = − 0.41, P = 0.003), weight (r = − 0.42, P = 0.002), priming volume as percentage of estimated blood volume (r = 0.30, P = 0.034), minimum CPB temperature (r = − 0.30, P = 0.033) and the change in clinical bleeding evaluation from T2 to T3 (r = 0.71, P < 0.001; Fig. 3). Patients weighing less than 8 kg had significantly higher scores in clinical bleeding evaluation after CPB (P = 0.039) and received significantly higher fibrinogen doses thereafter (mg kg− 1, P = 0.002). The plasma fibrinogen levels (Clauss method) correlated significantly with functional fibrinogen (r = 0.76) and MA-fib (r = 0.75, P < 0.0001 for both). The results of systemic perfusion after CPB evaluated by arteriovenous oxygen saturation difference (mean 26.8 ± 8.9) were adequate in all cases.

Fig. 2
figure2
Box and whisker plots (95th, 75th, 50th, and 5th percentiles) of TEG parameters (a-e) and clinical bleeding evaluated by surgeon (f) at baseline (T1), after bypass and administration of protamine (T2), at sternal closure (T3), and in ICU after 12 h (T4). Abbreviations: R, reaction time; K, kinetic time; MA, maximum amplitude; MA-fib, maximum amplitude of functional fibrinogen; NRS, numeric rating scale; * P < 0.001 (T1 vs T2), § P < 0.001 (T2 vs T3)

Full size image
Fig. 3
figure3
Correlation between administered total amount of fibrinogen kg− 1 and weight (a), priming volume as percentage of estimated blood volume weight (b), minimum temperature during cardiopulmonary bypass (c) and change in clinical bleeding evaluation from T2 to T3 (d). Abbreviations: Fib, fibrinogen; EBV, estimated blood volume; CPB, cardiopulmonary bypass; NRS, numeric rating scale

Full size image
In the ICU (T4), hematologic, coagulation standard and TEG parameters after 12 h remained stable. The mean chest drainage volume within the first six postoperative hours was 5.3 ± 2.9 (1.8–16.1) mLkg− 1; this is equivalent to 6.7 ± 3.7 (2.3–20.2) % loss of EBV. Four children (8%) had a postoperative blood loss of > 10% of EBV. Nine children (18%) received further red blood cell transfusions (mean 11.4 ± 2.4, 8–16 mL kg− 1) and one child 50 mg kg− 1 fibrinogen. Length of mechanical ventilation was 39 ± 51 (2–255) hours, and the mean ICU stay was 5.0 ± 3.9 (1-19) days. No child needed surgical re-intervention, no case of thrombosis was observed, and overall mortality was 0%.

Discussion
Our study showed that nearly all children with risk factors for bleeding presented with significant coagulation disorders after CPB, that an early preventive therapy with fibrinogen, prothrombin complex concentrate and platelets improved the hemostasis with no occurrence of thrombosis or need for re-operation and that a low body weight and a low CPB temperature were associated with higher administered fibrinogen doses (mg kg− 1).

Excessive bleeding after cardiopulmonary bypass is a serious complication and may be caused by coagulopathy and insufficient surgical hemostasis. Contributory mechanisms include heparinization and hemodilution through the circuit prime, exposure of blood to artificial surfaces, hypothermia and interactions between the inflammatory and coagulation systems [7]. Maintenance of a stable homeostasis is of high importance and therefore bicarbonate- buffered ultrafiltration was favored to achieve a physiologic priming solution and to prevent electrolyte and acid- base disturbances [6, 8]. Fresh frozen plasma (FFP) was added during rewarming and ultrafiltration on CPB to avoid fluid overload, but the results of clinical bleeding evaluation, TEG and standard coagulation parameters at T2 showed that FFP alone was not effective to prevent bleeding. Therefore, coagulation factor concentrates and platelets were added subsequently, and this strategy improved the results of clinical bleeding evaluation and thrombelastography significantly.

Prothrombin complex concentrates contain coagulation factors required to directly promote thrombin generation [5]. Studies including adults after CPB suggest that the use of prothrombin complex concentrate as part of a multimodal coagulation management strategy may have blood sparing effects [9, 10], but there is a lack of randomized controlled studies in both adult and pediatric patients. The main concern regarding the use of prothrombin complex concentrate is the possibility of thrombotic complications especially in children with a low cardiac output and artificial shunts [11]. Neither in our study or in our clinical practice have cases of thrombosis been observed, but the sample size was too low to assess safety. Therefore, the individual risk of thrombosis should be weighed against the perioperative risk of bleeding when using prothrombin complex concentrates in children undergoing complex pediatric cardiac surgery.

Fibrinogen is the major substrate for clot formation and additionally promotes platelet activation and agglomeration. Hemodilution from CPB results in decreased fibrinogen levels, which in turn results in impaired fibrin formation, inadequate clot formation and bleeding. Faraoni et al. [12] demonstrated in a retrospective analysis that the post-CPB plasma fibrinogen concentration significantly impacts blood loss in children undergoing cardiac surgery. Downey et al. [13] suggested that fibrinogen concentrate may be considered as an alternative to cryoprecipitate in infants with bleeding after CPB, but cryoprecipitate is not available in Germany. Mahovec et al. demonstrated that measuring fibrinogen levels during the rewarming phase of CPB reduced cryoprecipitate transfusion [14]. An animal experimental study showed that hemotherapy with fibrinogen did not affect arterial thrombogenesis [15]. Guidelines by the European Society of Anesthesiology recommend to keep the level of plasma fibrinogen at no less than 1.5 to 2 g L− 1 in bleeding patients [16]. In our study, most children had lower levels immediately after CPB but all had higher levels after fibrinogen administration at sternal closure. Therefore, keeping fibrinogen levels within a normal range should be one of the main goals to prevent bleeding in children undergoing complex cardiac surgery.

Platelet count and aggregation are markedly reduced after CPB, especially in neonates, and patients with impaired platelet function during CPB had markedly increased intraoperative transfusion requirements [17, 18]. Activation and aggregation of platelets following blood contact with foreign material, systemic inflammation, adverse effects of heparin on platelets and fibrinolytic system and hypothermia are among the most significant factors, but the relationship between postoperative bleeding and platelets dysfunction is a subject that is still being debated [4]. In our study, platelet counts were decreased in many children after CPB, but within a normal range after platelet transfusion at sternal closure. The platelet function was not analyzed, and therefore the hemostatic effect of the platelets transfused is unclear.

The TEG analyzer used in this study requires only a 300-μL blood sample and processes the sample automatically without a time-consuming pipette procedure. The results of the functional fibrinogen measurements correlated with the Clauss method, which is in accordance with a previous study by Gautam et al. [19]. To avoid a time delay, the hemostatic therapy should be started early after CPB if diffuse bleeding is clinically evident. Thereafter, the results of TEG analysis can be used to guide the hemostatic therapy in more detail until a stable clot formation is achieved [20]. In cases with difficult bleeding localization, this strategy can help to identify areas with surgical bleeding. Besides the results of TEG analysis, a close cooperation with the attending surgeon is important to evaluate the bleeding situation and the efficacy of the administered hemostatic therapy. Therefore, careful clinical evaluation should be performed and TEG analysis should be repeated to control success and to adapt the hemostatic therapy, if necessary. Cui et al. demonstrated that the use of TEG in children undergoing complex cardiac surgery reduced perioperative transfusion and improved the outcome [21].

In our study, neonates and infants < 8 kg had significantly higher scores in clinical bleeding evaluation after CPB and needed significantly higher fibrinogen doses (mg kg− 1) afterwards. These patients are at particular risk due to their immature coagulation systems and the mismatch between the CPB priming volume and the infants' blood volume [7]. Therefore, minimizing the priming volume and circuit should be an important goal, especially for small infants, and several studies reported safe use of miniaturized CPB circuits with a significant reduction of blood product transfusions [22,23,24]. While the benefits should be weighed against the downsides (e.g., reduced access to patient and circuit, vacuum assisted drainage - with the risk of air entrainment and hemolysis – often required, need for a very well-trained perfusion team), these techniques will probably be increasingly used in the future.

The incidence of clinically significant postoperative bleeding (8%) defined as postoperative drainage volume > 10% of EBV within the first six postoperative hours was more than two times lower when compared to other studies (incidence > 20%) [25, 26], even though these studies included also children without risk factors for bleeding. The major difference in hemostatic approach was the use of coagulation factors (fibrinogen, prothrombin complex concentrate) in the presented study. Also, other factors than hemostatic management alone may have contributed to the different results.

The presented study does, however, have some limitations. We performed a single-center prospective observational study on a special patient group (children below six years of age with one or more risk factors for bleeding) and the results may not be applicable to other populations. The attending anesthesiologists and surgeons were not blinded, and the sample size was too low to assess safety. The study design was observational and a randomization into groups of different fixed coagulation therapy regimens or a control group was not possible because of ethical reasons.

In conclusion, in this observational study of children with an increased risk of bleeding after complex cardiac surgery, an early preventive therapy with fibrinogen, prothrombin complex and platelets guided by clinical bleeding evaluation and thromboelastography (TEG) reduced bleeding and improved TEG and standard coagulation parameters significantly, with no occurrence of thrombosis or need for re-operation. Further studies are necessary to assess safety.

Availability of data and materials
The datasets used and/or analyzed during the study are available from the corresponding author on reasonable request.

Abbreviations
CPB:
Cardiopulmonary bypass

NRS:
Numeric rating scale

TEG:
Thrombelastography

ACT:
Activated clotting time

R:
Reaction time

K:
Kinetic time

MA:
Maximum amplitude

MA-fib:
Maximum amplitude of functional fibrinogen

LY30:
Fibrinolysis at 30 min after maximum amplitude

ICU:
Intensive care unit

FFP:
Fresh frozen plasma

EBV:
Estimated blood volume

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First pediatric electronic algorithm to stratify risk of penicillin allergy

Letter to the editor
Open Access
Published: 04 December 2020
First pediatric electronic algorithm to stratify risk of penicillin allergy
Hannah Roberts, Lianne Soller, Karen Ng, Edmond S. Chan, Ashley Roberts, Kristopher Kang, Kyla J. Hildebrand & Tiffany Wong
Allergy, Asthma & Clinical Immunology volume 16, Article number: 103 (2020) Cite this article

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Abstract
Beta-lactam allergy is reported in 5–10% of children in North America, but up to 94–97% of patients are deemed not allergic after allergist assessment. The utility of standardized skin testing for penicillin allergy in the pediatric population has been recently questioned. Oral drug challenges when appropriate, are preferred over skin testing, and can definitively rule out immediate, IgE-mediated drug allergy. To our knowledge, this is the only pediatric study to assess the reliability of a penicillin allergy stratification tool using a paper and electronic clinical algorithm. By using an electronic algorithm, we identified 61 patients (of 95 deemed not allergic by gold standard allergist decision) as low risk for penicillin allergy, with no false negatives and without the need for allergist assessment or skin testing. In this study, we demonstrate that an electronic algorithm can be used by various pediatric clinicians when evaluating possible penicillin allergy to reliably identify low risk patients. We identified the electronic algorithm was superior to the paper version, capturing an even higher percentage of low risk patients than the paper version. By developing an electronic algorithm to accurately assess penicillin allergy risk based on appropriate history, without the need for diagnostic testing or allergist assessment, we can empower non-allergist health care professionals to safely de-label low risk pediatric patients and assist in alleviating subspecialty wait times for penicillin allergy assessment.

Main text
To the editor,

Beta-lactam allergy is reported in 5–10% of children in North America [1,2,3], but up to 94–97% of patients are deemed not allergic after allergist assessment [4,5,6]. Reasons for the disparity between perceived and true drug allergy include predictable antibiotic side effects and symptoms of underlying infection, frequently mistaken for adverse drug reaction. Recently, the utility of standardized skin testing for penicillin allergy in the pediatric population has been questioned as recent literature has demonstrated that penicillin skin testing in pediatric patients can be less predictive of risk of IgE-mediated allergy [7]. Oral drug challenges are the gold standard in definitively ruling out immediate, IgE-mediated drug allergy [6].

Given the high demand for allergist assessment for perceived penicillin allergy (which in most cases is erroneously labeled) [1,2,3], along with the lack of resources and allergists to assess these cases in a timely manner, we aimed to create a clinical algorithm which could be applied by a variety of health care providers, without the need for allergist assessment, to accurately identify low risk patients.

This study was approved by UBC C&W Research Ethics Board and informed patient consent was obtained. A structured penicillin allergy questionnaire was administered to the patient/parent by an antimicrobial stewardship pharmacist. The same questionnaire was administered separately by a pediatric allergist during their standard drug allergy consultation, and skin testing and/or drug challenge was conducted, as indicated. The allergist's final assessment categorized the patient as (1) Allergic (IgE-mediated allergy or severe cutaneous/systemic adverse reaction) or (2) Not allergic and was deemed the "gold standard" decision.

All penicillin allergy questionnaires were independently reviewed by three pediatric allergists, a general pediatrician, a pediatric infectious disease specialist, and an antimicrobial stewardship pharmacist, hereafter referred to as the "assessors". These assessors were blinded to the gold standard allergist decision. The assessors were asked to follow a clinical algorithm on paper and categorize patients into one of the following risk levels: (1) Possible IgE-mediated allergy, (2) Low risk for allergy, (3) Allergic (previously assessed by an allergist), or (4) Suspected severe cutaneous/systemic adverse reaction, based on the answers to the penicillin allergy questionnaires. The assessors then indicated an "action plan" for the patient. They chose either (1) Penicillin may be prescribed again or (2) Avoid penicillin and refer to pediatric allergist.

An electronic version of the paper clinical algorithm was created using Excel, which automatically calculated risk level and action plan based on the answers applied from the penicillin allergy questionnaires. The electronic version was developed to minimize human error, which could arise by applying the paper algorithm manually, and ensure each step is accounted for. Different versions of the algorithm were tested to determine which was the most accurate at classifying patient risk level, compared to the gold standard allergist diagnoses, without increasing the number of false negatives (Table 1).

Table 1 Assessment of penicillin allergy risk using an electronic algorithm, compared with the clinical algorithm and gold standard allergist diagnosis
Full size table
We performed a power calculation using a 0.05 alpha (standard) and 80% power to detect an effect size of 0.4. for a goal sample size of 204 assessments (104 total subjects). Descriptive statistics were compiled for all variables. The decisions for risk level were compared across all assessors and a kappa statistic was calculated. Comparisons were made between assessor decision of risk level and the gold standard allergist decision. The assessor decision of risk level was compared with the electronic algorithm, and the two different permutations of it. Sensitivity and specificity were calculated for each of the versions of the electronic algorithm, compared with the gold standard allergist decisions. Data analysis was performed using Stata 15.

From July 2016 to May 2018, 117 patients were approached and 107 participated in our study at BC Children's Hospital (response rate = 91.5%). Due to missing information for 3 patients, 104 patients are included in the analysis. See Table 2 for patient information.

Table 2 Clinical and Demographic Patient Characteristics
Full size table
Of the gold standard allergist decisions, 91% (95/104) of patients were deemed "Not Allergic". Eight patients on history were identified to have non-IgE-mediated, serum sickness-like reactions. Only one patient was labeled as having an immediate, IgE-mediated penicillin allergy, with a positive skin test, and was not challenged. Based on history alone, 37 patients (39%) were identified as low risk for penicillin allergy using the clinical algorithm, 43 (45%) using the initial electronic algorithm, and 61 (64%) with the final electronic algorithm (Table 1). A total of 71 patients deemed low risk for penicillin allergy pursued successful oral drug challenges without skin testing. This included all 37 patients identified as low-risk with the clinical algorithm and the 61 patients identified using the electronic algorithm. A total of 89 patients completed successful oral drug challenges with no immediate adverse reactions; the majority (80%) without skin testing prior to challenge. Only two patients developed delayed, mild skin rashes post challenge. One of these patients had mild symptoms of an upper respiratory tract infection at the time of challenge. She was re-challenged at a later date and the challenge was successful. The other child was re-challenged and developed a mild macular rash after one hour of observation without systemic symptoms.

When the assessors manually applied the clinical algorithm, 37 patients were low risk for penicillin allergy based on history alone (Table 1). In all cases where there was disagreement, the non-allergist had a more conservative decision, categorizing the patient as "Possible IgE-mediated allergy" with an action plan to refer to an allergist. The sensitivity of the clinical algorithm for allergy (based on the gold standard allergist diagnosis) was 100%.

Applying the questionnaire answers into the initial electronic algorithm, 45% of patients were identified as low risk based on history alone. Altering the timing of resolution in the delayed symptoms category from > 48 h, to include symptoms lasting > 24 h (permutation 2), the number of patients identified as low risk increased to 64% (refer to Delayed Symptoms category in Fig. 1). In all cases the sensitivity of the electronic algorithm for allergy was 100%. This alternate version (permutation 2) of the algorithm had higher agreement with the gold standard allergist diagnosis (i.e. improved specificity) with no sacrifice in patient safety.

Fig. 1
figure1
Clinical Algorithm to identify pediatric patients at very low-risk of having penicillin allergy

Full size image
We demonstrated that by using a clinical algorithm (Fig. 1), a variety of pediatric health care professionals were able to safely and accurately risk stratify penicillin allergy. The electronic version of the algorithm further minimizes the risk of human error and captured an even higher percentage of low risk penicillin allergy patients than the paper version, making it superior. Although the paper and electronic algorithms are the same, and technically the paper version should yield the same result as the electronic version if users were to apply them correctly every time, they did not yield the same results. The most likely cause is that physicians were not following the algorithm on paper precisely and instead have personal bias related to past experiences and differences in personal risk threshold, that affect the final decision. Additional studies using this algorithm on an even larger scale in outpatient settings will be important to further corroborate our results and confirm safety.

A limitation of our study is that our population comes from only one pediatric center. In addition, our recommended algorithm relies on recall of the possible reaction, which may not be accurately reported for those with remote histories. Fortunately, remote histories are less likely in the pediatric population compared to the adult population. It is worth noting that timing of resolution of symptoms can depend on treatment. Reassuringly, even if symptom duration is decreased due to medication administration, the worst case scenario typically leads to a patient being placed in the high risk category, which does not reduce safety of the algorithm/patient, only potential delay in de-labeling while awaiting allergist consultation. A detailed clinical history, including specific management taken, is important in drug allergy assessment to ensure recognition of severe, delayed reactions which are contraindications to oral challenges. Six eligible low risk patients did not complete oral drug challenges secondary to being lost to follow-up or patient preference. We suspect our numbers for successful challenges would have been even higher with increased patient participation.

To our knowledge, this is the only pediatric study to assess the reliability of a penicillin allergy risk stratification tool, using both paper and electronic clinical algorithms. By using an electronic algorithm, we identified 61 patients (of the 95 deemed not allergic by gold standard allergist decision) as low risk, with no false negatives and without the need for allergist assessment or skin testing. Consistent with previous studies, our results confirm that the majority of patients with suspected penicillin allergy do not have immediate, IgE-mediated drug allergy [6, 8,9,10,11].

We demonstrate in this study that an electronic algorithm can be used by various pediatric clinicians when evaluating possible penicillin allergy to reliably identify low risk patients. We identified the electronic algorithm was superior to the paper version, capturing an even higher percentage of low risk patients. Electronic algorithms have an advantage over manual/paper algorithms in that they can be converted into a webpage or an application that can be easily accessed by clinicians using electronic devices, which is advantageous. They additionally have the ability to be incorporated into electronic health records.

By creating an electronic algorithm to accurately assess penicillin allergy risk based on appropriate history, without the need for diagnostic testing or allergist assessment, we can empower non-allergist health care professionals to identify and safely de-label low risk pediatric patients. This will assist in alleviating subspecialty wait times for penicillin allergy assessment, by ensuring that referrals to allergists are reserved for children with a higher probability of true, IgE-mediated drug allergy or severe, delayed reactions.

Availability of data and materials
Not applicable.

Abbreviations
IgE:
Immunoglobulin E

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Serum defensin levels in patients with systemic sclerosis

Research
Open Access
Published: 22 December 2020
Serum defensin levels in patients with systemic sclerosis
Tugce Emiroglu Gedik, Hamit Kucuk, Berna Goker, Seminur Haznedaroglu, Hatice Pasaoglu, Ozkan Varan, Mehmet Akif Ozturk, Ozge Tugce Pasaoglu & Abdurrahman Tufan
Advances in Rheumatology volume 60, Article number: 54 (2020) Cite this article

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Abstract
Background
Systemic sclerosis (SSc) is an autoimmune disease characterized by fibrosis of skin and lung as well as involvement of kidney, gastrointestinal system and heart. Aetiology and exact mechanism of disease is poorly understood. The association between antimicrobial peptides (AMPs) and other diseases such as idiopathic pulmonary fibrosis, diffuse panbronchiolitis, pulmoner alveolar proteinosis and psoriasis have been reported. A small number of studies have examined the role of AMPs on autoimmune diseases which has not been studied in scleroderma yet. We aimed to investigate AMP serum levels and their association with disease characteristics of SSc.

Methods
Forty-two patients (40 female, mean age 42 years) and 38 healthy subjects (32 female, mean age 38 years) were enrolled. For SSc patients, the following data were recorded: disease subset (limited/diffuse), autoantibodies (antinuclear, anti-centromere (ACA), and anti-SCL-70), blood tests, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP), modified Rodnan skin score, presence and history of digital ulcers, kidney, gastrointestinal disease and lung involvement assessed by computed tomography and pulmonary function tests. Association between serum AMPs and disease characteristics were analysed.

Results
Twenty-nine of the patients had diffuse (69%) and 13 of the patients had limited (31%) systemic sclerosis. Average disease duration was 5.5 years. Pulmonary involvement was detected in 20 patients (47.6%). Serum concentration of alpha defensin was higher than healthy subjects (563 ± 415 vs 377 ± 269 ng/mL, p = 0.02). However, no difference was observed for beta-1 and beta-2 defensins in SSc patients and healthy controls. In sub-group analysis patients with interstitial lung disease had higher levels of alpha defensin than those without lung involvement (684 ± 473 vs 430 ± 299 ng/ml, p = 0.04). There was also correlation between alfa defensin serum concentrations and CRP (r = 0.34).

Conclusions
Alpha defensin levels are increased in scleroderma patients and correlated with lung involvement indicating a role in the pathogenesis of disease.

Trial registration
This study is not a clinical trial study.

Introduction
Systemic sclerosis (SSc) is a chronic multisystemic autoimmune disease manifested by diffuse fibrosis of the skin and internal organs [1]. Although the pathogenesis of the disease is largely unknown, three major pathologic changes take part in its evolution; fibrosis, vasculopathy and inflammation. SSc is largely considered as an autoimmune disease with activation of both innate and adaptive components of immune system [2].

One of the critical components of innate immune system is antimicrobial peptides (AMPs). There are hundreds of structurally different peptides with antimicrobial properties which are found in all eukaryotic organisms. AMPs are particularly synthesized in mucosal epithelial cells and neutrophils that are constantly in contact with microorganisms in the body. In humans, there are three main family of AMPs; defensins, cathelicidin (LL37) and histatin [3]. Alpha-defensins (HNP1) are primarily expressed in neutrophils, while beta-defensins and LL37 are constitutively synthesized and secreted from epithelial surfaces, therefore called as epithelial AMPs [4]. AMPs have direct microbicidal effects and play critical role in cleaning intracellular microorganisms and fighting against cancer cells [5, 6]. Besides having direct antimicrobial effects, AMPs can incite inflammation by activating immune effector cells and chemotaxis of neutrophils [4]. Epithelial AMPs may stimulate production of pro-inflammatory cytokines such as IL-17, IL-22, and TNF alpha [7]. Another important role of AMPs involves the maintenance of the host microbiota besides their antimicrobial functions.

To date, limited number of studies have investigated the relationship between antimicrobial peptides and autoimmune/inflammatory diseases. In patients with systemic lupus erythematosus (SLE), alpha defensin and beta-2 defensin levels were found elevated and related with disease activity [8, 9]. There is not much literature on the potential role of AMPs in SjS; however, some studies suggest that cathelicidin and defensins may have a role in the pathophysiology of the disease [10]. The role of AMPs in pulmonary diseases have been shown in idiopathic pulmonary fibrosis, diffuse panbronchiolitis and pulmonary alveolar proteinosis. The role of AMPs are scarcely studied in scleroderma and there is downregulation of LL-37 in diffuse SSc patients [11] and tissue beta defensin of localized scleroderma after UVA-1 treatment [12]. Herein, we aimed to investigate alpha and beta defensin serum concentrations in patients with SSc and their association with disease characteristics.

Materials and methods
The study included consecutive SSc patients over 18 years of age who met the diagnostic criteria for SSc [13]. Patients with other autoimmune disease or overlap syndromes, infections, immunodeficiency, chronic liver and kidney dysfunction were excluded from the study. Patients receiving corticosteroids and immuno-suppressive drugs were excluded from the study. Control group consisted age- and sex-matched healthy subjects. Written consent was obtained and included in the study. All participants were informed about the objectives of the study and gave their signed consent for inclusion. The study was approved by the local ethics committee (Ethics committee approval ID: 28.09.2015/3).

Demographic and clinical features of SSc patients were obtained by patient interviews and hospital file records. Detailed physical examination was performed for each patient and skin fibrosis was assessed by an experienced physician. Laboratory parameters, acute phase reactants and serologic tests including anti-nuclear antibodies, anti-scl-70 and anti-centromere antibodies were retrieved from computer based hospital records. Pulmonary function tests, high resolution thorax computed tomography (HRCT) and echocardiographic findings were recorded. Interstitial lung disease was defined as interstitial fibrosis, reticulation or alveolitis on high-resolution computer tomography. Pulmonary hypertension was defined as mean pulmonary artery pressure ≥ 25 mm/Hg. Gastrointestinal involvement was evaluated in all subjects with oesophageal manometry and considered positive if there was consistent findings. Finally, SSc patients were categorized by LeRoy's classification system as diffuse and limited SSc [14].

Blood samples were taken from antecubital vein after overnight fasting at morning hours and immediately centrifuged. Sera was separated and stored at − 80 °C until they studied. Serum alpha defensin (HNP1), beta-defensin 1 and 2 levels were determined by using commercial enzyme-linked immunosorbent assay (ELISA) kits (Assay Biotech, USA).

Statistical Package for the Social Sciences software v16.0 (SPSS Inc., Chicago, IL) was used for statistical analysis. Categorical data were expressed as numbers and percentages. Chi square test was used to compare categorical variables. Normality distribution of continuous variables were evaluated with using Kolmogorov-Smirnov test. Continuous variables are expressed as median [Interquartile range (IQR)] values since they did not show normal distribution. Continuous variables of groups were compared with Mann-Whitney U and Kruskal-Wallis tests. Spearman Rho was used for correlation analyzes. Differences between groups were considered significant at the 5% level (p < 0.05).

Results
A total of 80 individuals, 42 SSc patients and 38 healthy control subjects were included in the study. Forty patients were female and mean age of patients was 42 ± 11 years. Mean age of control group was 38 ± 11 years and 32 were female.

Twenty-nine (69%) patients had diffuse and 13 patients (31%) had limited systemic sclerosis. The mean disease duration was 5.5 ± 4.8 years. Organ involvements of the patients are presented in Table 1. Pulmonary involvement on HRCT was evident in 20 (47.6%) patients.

Table 1 Clinical manifestations of systemic sclerosis patients
Full size table
Serum alpha defensin levels of SSc patients were significantly higher than control subjects (563 ± 415 vs 377 ± 269 ng/mL,p = 0.02). However no differences were observed in serum concentrations of epithelial defensins ─ beta-1 and beta-2 between SSc patients with healthy subjects (beta-1 defensin 235 ± 178 vs 185 ± 24 pg/mL, p = 0.08 and beta-2 defensin 253 ± 453 vs 152 ± 101 pg/ml, p = 0.1). There were no statistically significant differences in alpha, beta-1 and beta-2 defensin levels between diffuse and limited forms of SSc (p = 0.08, p = 0.56, p = 0.57; respectively). In sub-group analysis, with regard to organ involvements, patients with interstitial lung disease had remarkably higher levels of alpha defensins than those without lung involvement (684 ± 473 vs 430 ± 299 ng/mL, p = 0.04, Table 2). However any association was found between organ manifestations and serum concentrations of epithelial defensins ─ beta-1 and beta-2 in patients with SSc. There was a correlation between CRP (r = 0.345, p = 0.03), modified Rodnan Score (r = 0.296 p = 0.07) and % forced vital capacity FVC (r = 0.306 p = 0.07).

Table 2 Alpha defensin levels according to clinical manifestations of systemic sclerosis
Full size table
Discussion
In this cross-sectional study, we investigated serum levels of the one of the major antimicrobial peptide family, defensins. We found that serum concentrations of alpha defensins are increased in SSc patients. Moreover, elevation in serum alpha defensin (HNP-α) was more remarkable in SSc patients with pulmonary involvement.

AMPs are part of the innate immunity with capability of activating adaptive immune system [15]. The level of AMP expression varies among individuals, and it has been suggested that this variation is due to genetic differences in the genes encoding defensins. These peptides are also known as danger signals or" alarmins" playing important roles in inflammation and immunity [16]. AMPs can be released into the extracellular area following granulocyte activation as a consequence of degranulation, cell death, leakage, and lysis during inflammation [17]. Recent studies show that the abnormal production of AMPs produced by neutrophils or epithelial cells promotes inflammation by supporting the autoimmune response. However, there are not enough studies related to the significance of abnormal levels of AMPs in SSc.

AMP levels have been studied in some inflammatory diseases such as rheumatoid arthritis, SLE, inflammatory bowel disease, psoriasis, atopic dermatitis and familial Mediterranean fever (FMF). These studies showed that AMPs expression were irregular in diseases such as systemic lupus erythematosus (SLE), psoriasis, rheumatoid arthritis (RA), type 1 diabetes (T1D), Sjögren's disease (SjS) and multiple sclerosis (MS) [10]. Hiroyuki Tamiya et al. reported significantly higher defensin and cathelicidin levels in active SLE patients [18]. Tufan et al. found similar results in FMF patients that increased alpha- defensin and cathelicidin levels with no significant difference for beta-2-defensin [19]. In another study on psoriasis patients, use of serum beta-2-defensin levels are suggested as a marker reflecting psoriasis disease activity [20]. Cathelicidin and human beta-defensins 2 and 3 (hBD2/3) have been shown to be highly expressed in the psoriatic skin of patients [21, 22]. The expression of human neutrophil peptides (HNPs) 1–3 was significantly increased in the synovial cavity of patients with RA and related with joint erosion [23].

Previous studies have demonstrated increased AMP levels in inflammatory lung diseases. It was shown that HNP levels were 50 times higher in bronchoalveolar lavage samples of ARDS patients [24]. In a study by Noriho Sakamoto et al., AMP levels were studied in patients with interstitial pneumonia (IP). Their study included 21 acute attack IP, 44 stable IP, 9 infected IP patients and 23 healthy controls. The level of alpha-defensin was found to be significantly increased in patients with acute exacerbation. Beta- defensin-2 was found to be higher in patients with stable IP than in healthy controls [25]. Mukae et al. found that serum alpha-defensin levels were higher in patients with idiopatic pulmonary fibrosis (IPF) compared to control group. But no difference was found between bronchoalveolar lavage levels [26]. In another study, Mukae et al. compared defensin levels of IPF, cryptogenic organized pneumonia (COP), pulmonary alveolar proteinosis PAP), sarcoidosis, and idiopathic nonspecific interstitial pneumonia (NSIP) patients and defensin levels were significantly higher than the control group. There was a significant difference between the diseases as well. Beta defensin-1 levels were significantly higher in IPF, COP, NSIP and sarcoidosis patients compared to the control group. Beta-2 defensin levels were significantly higher in sarcoidosis and IPF patients compared to the control group [27].

Defensin family AMPs have not been thoroughly studied in patients with SSc. In our study, we aimed to determine serum levels of main defensins and their association with disease characteristics. We found significantly increased serum alpha defensin levels particularly in those with interstitial lung involvement. Alpha-defensin is mainly released from neutrophils and activate neutrophils with a positive feedback loop and they might contribute lung inflammation observed in SSc and other pathologies. Supporting this hypothesis, serum alpha defensin levels were correlated with acute phase reactants. Interestingly, serum alpha defensin levels were also correlated with skin fibrosis suggesting a role in the pathogenesis of fibrosis. An in vitro study investigated effects of alpha defensin in lung tissue that it enhanced expression of IL-8 in epithelial cells as well as transforming growth factor-beta and vascular endothelial growth factor expressions in lung fibroblasts [28]. Another study confirmed that alpha-defensin contribute neutrophilic lung inflammation via inducing synthesis of a strong neutrophil chemoattractant, IL-8, in airway epithelial cells [29].

In a previous study, Kuzumi et al. reported decreased serum beta-2 defensin levels in SSc patients which was highly dependent on duration of disease [30]. In that study they found significant associations between beta-2 defensin and telangiectasia, pitting scars and digital ulcers suggesting its contribution to pathogenesis of vasculopathy observed in SSc. However they did not find an association with lung involvement [30]. In our study, we did not find a difference for beta-1 and beta-2 defensin levels in SSc patients compared to healthy subjects. Discrepancy between results of studies can be explained by differences in clinical manifestations of patients and duration of disease.

We have several limitations in our study. First, we did not assess serum cytokine levels in SSc patients which might demonstrate association between defensins and inflammatory and fibrotic mediators. Second, number of SSc patients are relatively small and inclusion of more patients might reveal better results.

Conclusions
In conclusion, serum alpha defensin concentrations are increased in SSc patients and associated with lung involvement and skin fibrosis. Further studies involving more patients and detailed molecular tests are needed to determine whether these molecules contribute to the course and pathogenesis of systemic sclerosis.

Availability of data and materials
The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.

Abbreviations
ANA:
Anti-nucleer antibody

AMP:
Antimicrobial peptides

DLCO:
Diffusing Capacity of Lung for Carbon Monoxide test

ECG:
Elektrocardiografi

Echo:
Echocardiografi

FEV-1:
Functional Expiratory Volume

FVC:
Force vital capacity

hBD − 1.2.3:
Human Beta defensins 1.2.3

HRCT:
High resolution computerized tomography

HNP:
Human Neutrophil Peptides

Rf:
Raynaud Fenomeni

PAH:
Pulmoner Arteryel Hypertension

RFT:
Respiratory function test

SSk:
Sistemik Skleroz

SP-D:
Surfaktan protein

COP:
Cryptogenic organized pneumonia

PAP:
Pulmonary alveolar proteinosis

NSIP:
Idiopathic nonspecific interstitial pneumonia

AMP:
Antimicrobial peptides

ARDS:
Acute respiratuar distress syndrome

FMF:
Familial Mediterranean fever

IPF:
Idiopatic pulmonary fibrosis

ELISA:
Enzyme-linked immunosorbent assay

RNP:
Ribonucleoprotein

IQR:
Interquartile range

ACA:
Anti-centromere

ESR:
Erythrocyte sedimentation rate

CRP:
C-reactive protein

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Medicine by Alexandros G. Sfakianakis,Anapafseos 5 Agios Nikolaos 72100 Crete Greece,00302841026182,00306932607174,alsfakia@gmail.com,
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