Validation of an Aerobic Fitness Questionnaire to estimate VO2 peak in a cohort of adult cardiac patients - Is it enough?

Abstract

Introduction and objectives: Cardiopulmonary exercise testing (CPET) is the gold standard for quantifying aerobic functional capacity, yet it is costly and not widely available. The CLINIMEX Aerobic Fitness Questionnaire (C-AFQ) may be a practical alternative as it estimates oxygen consumption at peak exercise (VO₂ peak) based on patients' responses to a list of activities with known energy requirements. However, its applicability in cardiac patients is unclear and has not yet been studied. This study aims to assess the C-AFQ performance in predicting VO₂ peak, measured via CPET, in adult patients with confirmed heart disease.

Methods: This was a single-center prospective study enrolling consecutive patients who underwent CPET from April/2022-January/2023. The main indication for CPET was measuring aerobic functional capacity for cardiovascular risk stratification.

Results: A total of 124 patients (mean age 62±12 years, 75% male, 59% in the early phase post-myocardial infarction, 61% had heart failure, mean left ventricular ejection fraction 47±12%) with maximal CPET were included. Overall, a strong correlation was found between CPET and C-AFQ VO₂ peak values (r=0.723, p<0.001). However, when performing a Bland-Altman plot analysis, we found a heightened confidence interval for the agreement between CPET and C-AFQ VO₂ peak: 0.62±6.93 (95% CI -12.96-14.21) mL.kg^-1.min^-1. CPET VO₂ peak and the VO₂ peak estimated by the exercise test protocol were related (r=0.777, p<0.001).

Conclusion: Although cardiorespiratory fitness estimation from the C-AFQ performs well in a large population, the utility of this questionnaire to estimate cardiorespiratory fitness in this study´s population sample has limited value. However, it may be useful to aid physicians in choosing the adequate exercise test protocol that best fits an individual patient.