Estimating VO_2peak in 18-91 year-old adults: Development and Validation of the FitMáx^© - Questionnaire

Abstract

Objectives: Cardiorespiratory fitness plays an essential role in health outcomes and quality of life. Objective assessment of cardiorespiratory fitness is costly, labour intensive and not widely available. Although patient-reported outcome measures estimate cardiorespiratory fitness more cost-efficiently, the current questionnaires lack accuracy. The aim of this study is to develop and validate the FitMáx©-questionnaire, a self-reported questionnaire to estimate cardiorespiratory fitness in healthcare. Methods: We developed the FitMáx©-questionnaire, consisting of three questions assessing walking, stair climbing, and cycling capacity. A comparison on estimating VO2peak was made with the Duke Activity Status Index (DASI), Veterans Specific Activity Questionnaire (VSAQ) and cardiopulmonary exercise testing as the gold standard. A total of 716 patients and athletes (520 men, 196 women) aged 18‒91 performed a CPET in our hospital. We randomly selected 70% of the subjects to fit a linear regression model to estimate VO2peak based on the FitMáx© scores. The remaining 30% of participants was used for validation of this model. Results: The VO2peak estimated by the FitMáx© strongly correlates with the VO2peak measured objectively with CPET; r=0.95 (0.93‒0.96) SEE=3.94 ml∙kg-1∙min-1. Bias between predicted and measured VO2peak was 0.32 ml·kg-1·min-1 and the 95% limits of agreement were -8.11 ‒ 9.40 ml∙kg-1∙min-1. In our sample, the FitMáx© scored superiorly on correlation and SEE compared with those from the DASI and VSAQ, r=0.80 (0.73‒0.86) SEE=4.22 ml∙kg-1∙min-1 and r=0.88 (0.84‒0.91) SEE=6.61 ml∙kg-1∙min-1, respectively. Conclusion: FitMáx© is a valid and accessible questionnaire to estimate cardiorespiratory fitness expressed as VO2peak and shows substantial improvement compared to currently used questionnaires.