Estimating VO2peak in 18-91 year-old adults: Development and validation of the FitMax - Questionnaire

ObjectivesCardiorespiratory 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 FitMax(C)-questionnaire, a self-reported questionnaire to estimate cardiorespiratory fitness in healthcare. MethodsWe developed the FitMax(C)-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{square}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 FitMax(C) scores. The remaining 30% of participants was used for validation of this model. ResultsThe VO2peak estimated by the FitMax(C) strongly correlates with the VO2peak measured objectively with CPET; r=0.95 (0.93{square}0.96) SEE=3.94 ml{middle dot}kg-1{middle dot}min-1. Bias between predicted and measured VO2peak was 0.32 ml{middle dot}kg-1{middle dot}min-1 and the 95% limits of agreement were -8.11 {square} 9.40 ml{middle dot}kg-1{middle dot}min-1. In our sample, the FitMax scored superiorly on correlation and SEE compared with those from the DASI and VSAQ, r=0.80 (0.73{square}0.86) SEE=4.22 ml{middle dot}kg-1{middle dot}min-1 and r=0.88 (0.84{square}0.91) SEE=6.61 ml{middle dot}kg-1{middle dot}min-1, respectively. ConclusionFitMax(C) is a valid and accessible questionnaire to estimate cardiorespiratory fitness expressed as VO2peak and shows substantial improvement compared to currently used questionnaires. Key pointsO_LIFitMax(C) relies on three simple single-answer questions, which are recognizable for a large population, to accurately estimate cardiorespiratory fitness. C_LIO_LIThe FitMax(C) is a self-reported instrument in which involvement of physicians, healthcare providers or other instrumentation is not necessary. C_LIO_LICardiorespiratory fitness estimated by the FitMax(C) may serve as an easily applicable measure in clinical and non-clinical settings. C_LI