CRITERION VALIDITY AND RESPONSIVENESS OF THE FITMÁX© AND OTHER SELF-REPORTED QUESTIONNAIRES TO EVALUATE AEROBIC CAPACITY IN SURVIVORS OF CANCER

A.T. Weemaes^1,2, R. Meijer^3,4, M. Beelen^1,5, M.P. Weijenberg⁶, L.V. van de Poll-Franse^7,8,9, H.H. Savelberg⁴, G. Schep³

¹Maastricht University Medical Centre+, Department of Physiotherapy, Maastricht, Netherlands, ²Maastricht University, Department of Epidemiology, Care and Public Health Research Institute (CAPHRI), Maastricht, Netherlands, ³Máxima Medical Centre, Department of Sports and Exercise, Veldhoven, Netherlands, ⁴Maastricht University, Department of Nutrition and Movement Sciences, School of Nutrition and Translational Research in Metabolism (NUTRIM), Maastricht, Netherlands, ⁵Maastricht University, Department of Human Biology, School of Nutrition and Translational Research in Metabolism (NUTRIM), Maastricht, Netherlands, ⁶Maastricht University, Department of Epidemiology, GROW School for Oncology and Reproduction, Maastricht, Netherlands, ⁷Netherlands Comprehensive Cancer Organization, Department of Research and Development, Utrecht, Netherlands, ⁸The Netherlands Cancer Institute, Divison of Psychosocial Research and Epidemiology, Amsterdam, Netherlands, ⁹Tilburg University, Department of Medical and Clinical Psychology, Tilburg, Netherlands

Background: The criterion standard to evaluate aerobic capacity is measuring peak oxygen uptake (VO_2peak) during cardiopulmonary exercise testing (CPET). Performing CPET is valuable for detecting causes of exercise limitation, personalized exercise prescription and monitoring aerobic capacity in patients with chronic diseases. However, CPET is not always feasible or necessary, and self-reported questionnaires might be a useful alternative. The Duke Activity Status Index (DASI) and Veterans Specific Activity Questionnaire (VSAQ) are self-reported questionnaires which are currently often used to evaluate aerobic capacity in patients. Although VSAQ and DASI showed a significant correlation with measured VO_2peak in previous studies, agreement was suboptimal. Recently, the FitMáx©-questionnaire (FitMáx) was developed to estimate VO_2peak based on the maximum capacity of walking, cycling and stairclimbing together with simple demographic characteristics.

Purpose: To evaluate the criterion validity and responsiveness of the FitMáx©-questionnaire, DASI and VSAQ, as self-reported questionnaires to evaluate aerobic capacity in survivors of cancer.

Methods: Survivors of cancer who were scheduled to participate in a 10-week supervised exercise program at the Maastricht University Medical Centre+ were included. The FitMáx, DASI, VSAQ and a CPET were completed before (T0) and after (T1) the program. Intraclass correlation coefficients (ICC) were calculated between VO_2peak estimated by the questionnaires (questionnaire-VO_2peak) and VO_2peakmeasured during CPET (CPET-VO_2peak) at T0 to examine criterion validity, and between changes (ΔT0-T1) to determine responsiveness. Receiver operating characteristic (ROC) analyses were performed to examine the ability of the questionnaires to detect true improvements (≥6%) in CPET-VO_2peak.

Results: Seventy-one participants were included. Mean age was 53.4 ±12.8 years and breast cancer was the most common diagnosis (39%). Mean CPET-VO_2peak at T0 was 18.8 ± 5.9 mL·kg^-1·min^-1 (61% of predicted). Agreement between questionnaire-VO_2peak and CPET-VO_2peak at T0 was moderate for the FitMáx (ICC=0.70) and VSAQ (ICC=0.54), and poor for the DASI (ICC=0.37). Outcomes at T1 were available for 59 participants (81%). Mean CPET-VO_2peak significantly improved at T1 (Δ1.6 mL·kg^-1·min^-1). Poor agreement was found between ΔCPET-VO_2peak and Δquestionnaire-VO_2peak for all questionnaires (ICC 0.41, 0.18 and 0.18 for the FitMáx, DASI and VSAQ, respectively). ROC analysis showed that the FitMáx was able to detect improvements in CPET-VO_2peak, when using a cut-off value of 1.0 mL·kg^-1·min^-1. The DASI and VSAQ were not able to detect improvement in CPET-VO_2peak.

Conclusions: The FitMáx has sufficient validity to estimate aerobic capacity in survivors of cancer at group level. The responsiveness of the FitMáx to measure absolute changes in aerobic capacity is limited, but the questionnaire is able to detect whether aerobic capacity improved, when using a cut-off value of 1.0 mL^.kg^-1.min^-1. The FitMáx showed substantial better values of validity and responsiveness compared to the DASI and VSAQ. Future studies should focus on validation of the FitMáx questionnaire in other study populations. Furthermore, refinements of the questionnaire and the prediction model can be made, to optimize the validity and responsiveness.

Implications: The FitMáx can be used to estimate and monitor aerobic capacity in survivors of cancer, but should be interpreted with caution, since the agreement with the gold standard is limited.
www.fitmaxquestionnaire.com/questionnaire

Funding acknowledgements: This work was partially funded by the National Foundation Against Cancer (NFtK).

Keywords:
Cardiopulmonary exercise testing
Self-reported questionnaires
Measurement properties

Topics:
Oncology, HIV & palliative care
Disability & rehabilitation
Health promotion & wellbeing/healthy ageing/physical activity

Did this work require ethics approval? Yes

Institution: Maastricht University Medical Centre+

Committee: Medical Ethics Committee azM/UM

Ethics number: 2020-2300