Cardiopulmonary exercise test registry for patients with obesity: comparison of cardiorespiratory fitness prediction equations and generation of a new predictive model for patients with obesity

Introduction Cardiorespiratory fitness (CRF) is a critical marker of overall health and a key predictor of morbidity and mortality, but the existing prediction CRF equations are primarily derived from general populations and may not be suitable for patients with obesity (PwO). Purpose This study examined the use of non-exercise prediction equations for estimating CRF (pCRF) in PwO and evaluated their accuracy compared to directly measured CRF (mCRF) through cardiopulmonary exercise testing (CPET). Methods pCRF from different non-exercise prediction equations was compared with mCRF of PwO who underwent maximal CPET. Multiple linear regression was used to develop a non-exercise prediction model for treadmill including age, sex, BMI, and physical activity level. Results 660 PwO underwent CPET during the study period (age = 44.2 ± 11.3 years, female = 69%, BMI = 41.8 ± 6.8 kg/m2). R2 values had a range of 0.24-0.46 with standard error of estimate ranged from 2.84-3.26 ml/kg/min. pCRF was statistically different from mCRF for 19 included equations. Only 50% of PwO were correctly classified into the mCRF categories according to pCRF. A multivariable model for a treadmill CRF prediction was generated (R2 = 0.57; standard error of estimate = 1.12 ml/kg/min) and validated using two cross-validation methods. Conclusions Most used equations provided inaccurate estimates of CRF in PwO, particularly in cases of severe obesity and low CRF. Therefore, a new prediction equation was developed and validated for PwO, offering a more precise tool for clinical CPET interpretation and risk stratification in this specific population. Figure 1 Figure 2