Monitoring aerobic capacity in cancer survivors using self-reported questionnaires: criterion validity and responsiveness

BackgroundEvaluating the criterion validity and responsiveness of the self-reported FitMax & COPY;-questionnaire, Duke Activity Status Index (DASI) and Veterans Specific Activity Questionnaire (VSAQ) to monitor aerobic capacity in cancer survivors.MethodsCancer survivors participating in a 10-week supervised exercise program were included. The FitMax & COPY;-questionnaire, DASI, VSAQ and a cardiopulmonary exercise test (CPET) were completed before (T-0) and after (T-1) the program. Intraclass correlation coefficients (ICC) were calculated between VO2peak estimated by the questionnaires (questionnaire-VO2peak) and VO2peak measured during CPET (CPET-VO2peak), at T-0 to examine criterion validity, and between changes in questionnaire-VO2peak and CPET-VO2peak (& UDelta;T-0-T-1) to determine responsiveness. Receiver operating characteristic (ROC) analyses were performed to examine the ability of the questionnaires to detect true improvements (& GE; 6%) in CPET-VO2peak.ResultsSeventy participants were included. Outcomes at T-1 were available for 58 participants (83%). Mean CPET-VO2peak significantly improved at T-1 (& UDelta;1.6 mL & BULL;kg(- 1)& BULL;min(- 1) or 8%). Agreement between questionnaire-VO2peak and CPET-VO2peak at T-0 was moderate for the FitMax & COPY;-questionnaire (ICC = 0.69) and VSAQ (ICC = 0.53), and poor for DASI (ICC = 0.36). Poor agreement was found between & UDelta;CPET-VO2peak and & UDelta;questionnaire-VO2peak for all questionnaires (ICC 0.43, 0.19 and 0.18 for the FitMax & COPY;-questionnaire, VSAQ and DASI, respectively). ROC analysis showed that the FitMax & COPY;-questionnaire was able to detect improvements in CPET-VO2peak (area under the curve, AUC = 0.77), when using a cut-off value of 1.0 mL & BULL;kg(- 1)& BULL;min(- 1), while VSAQ (AUC = 0.66) and DASI (AUC = 0.64) could not.ConclusionThe self-reported FitMax & COPY;-questionnaire has sufficient validity to estimate aerobic capacity in cancer survivors at group level. The responsiveness of the FitMax & COPY;-questionnaire for absolute change is limited, but the questionnaire is able to detect whether aerobic capacity improved. The FitMax & COPY;-questionnaire showed substantial better values of validity and responsiveness compared to DASI and VSAQ.