Validation and Refinement of Prediction Models to Estimate Exercise Capacity in Cancer Survivors Using the Steep Ramp Test.

Objective: To further test the validity and clinical usefulness of the steep ramp test (SRT) in estimating exercise tolerance in cancer survivors by external validation and extension of previously published prediction models for peak oxygen consumption (Vo _2peak ) and peak power output (W _peak ).
Design: Cross-sectional study.
Setting: Multicenter.
Participants: Cancer survivors (N=283) in 2 randomized controlled exercise trials.
Interventions: Not applicable.
Main Outcome Measures: Prediction model accuracy was assessed by intraclass 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.
Results: ICCs of SRT-predicted Vo _2peak and W _peak with these values as obtained by the cardiopulmonary exercise test were .61 and .73, respectively, using the previously published prediction models. 95% LOA were ±705mL/min with a bias of 190mL/min for Vo _2peak and ±59W with a bias of 5W for W _peak . Modest improvements were obtained by adding body weight and sex to the regression equation for the prediction of Vo _2peak (ICC, .73; 95% LOA, ±608mL/min) and by adding age, height, and sex for the prediction of W _peak (ICC, .81; 95% LOA, ±48W). Accuracy of endurance exercise prescription improved from 57% accurate prescriptions to 68% accurate prescriptions with the new prediction model for W _peak .
Conclusions: Predictions of Vo _2peak and W _peak based on the SRT are adequate at the group level, but insufficiently accurate in individual patients. The multivariable prediction model for W _peak can be used cautiously (eg, supplemented with a Borg score) to aid endurance exercise prescription.
(Copyright © 2017 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.)