Validation and refinement of prediction models to estimate exercise capacity in cancer survivors using the Steep Ramp Test

Publication date: Available online 18 March 2017
Source:Archives of Physical Medicine and Rehabilitation
Author(s): Martijn M. Stuiver, Caroline S. Kampshoff, Saskia Persoon, Wim Groen, Willem van Mechelen, Mai JM. Chinapaw, Johannes Brug, Frans Nollet, Marie-José Kersten, Goof Schep, Laurien M. Buffart
ObjectiveTo further test the validity and clinical usefulness of the Steep Ramp Test (SRT) for estimating exercise tolerance in cancer survivors, by external validation and extension of previously published prediction models for VO2peak and Wpeak.DesignCross-sectional study.SettingMulticenter.ParticipantsCardiopulmonary exercise tests (CPET) and SRT data from cancer survivors (n=283) in two randomized exercise trials.InterventionNot applicableMain outcome measuresPrediction model accuracy was assessed by intra class correlation coefficients (ICCs) and Limits of Agreement (LOA). Multiple linear regression was used for model extension. Clinical performance was judged by the percentage of accurate endurance exercise prescriptions.ResultsICCs of SRT-predicted VO2peak and Wpeak with these values as obtained by CPET were 0.61 and 0.73 respectively, using the previously published prediction models. 95%LOA were +/- 705 ml/min with a bias of 190 mL/min for VO2peak, and +/- 59W with a bias of 5W for Wpeak. Modest improvements were obtained by adding body weight and sex to the regression equation for prediction of VO2peak (ICC= 0.73, 95% LOA +/- 608 ml/min), and age, height and sex for prediction of Wpeak (ICC=0.81, 95%LOA +/- 48W). Accuracy of endurance exercise prescription improved from 57% accurate prescriptions to 68% accurate prescriptions with the new prediction model for Wpeak.ConclusionPredictions of VO2peak and Wpeak based on the SRT are adequate at the group level, but insufficiently accurate in individual patients. The multivariable prediction model for Wpeak can be used cautiously (e.g. supplemented with a Borg score) to aid endurance exercise prescription.



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