The Joint Association Of Cardiorespiratory Fitness And Body Mass Index On Cardiovascular Disease Mortality: A Meta-analysis

PURPOSE: Prevalence of overweight and obesity is increasing globally and is associated with cardiovascular disease (CVD) mortality. Cardiorespiratory fitness (CRF) is proposed as a clinical vital sign and has been shown to attenuate the CVD risks associated with obesity. The purpose of this meta-analysis was to assess the joint relationship of CRF and body mass index (BMI; normal - 18.5-24.9 kg/m2, overweight - 25.0-29.9 kg/m2, and obese - >30 kg/m2) on CVD mortality risk. METHODS: Electronic databases (PubMed/MEDLINE, Web of Science, and SportDiscus) were searched following registration on PROSPERO for articles meeting the following a priori criteria for inclusion: 1) published between January 1980 and February 2023, 2) prospective cohort studies, 3) CRF assessed using a maximal or VO2peak exercise test, 4) BMI was reported and directly measured in clinic, 5) joint impact of CRF and BMI on all-cause mortality or CVD mortality were analyzed, 6) the reference group was normal weight, fit individuals. Pooled hazard ratios (HR) and 95% confidence intervals (CI) were calculated using a three-level, restricted maximum likelihood estimation random-effects model, with robust variance estimation. The reference group was compared to the following: normal weight-unfit, overweight-unfit and fit, obese-unfit and fit. α was set at 0.05. RESULTS: Thirteen articles were included in the final analyses with the sample age ranging from 42.4-53.5 years and follow-up ranging from 8.1-26 years. Compared to the reference group (normal weight-fit), overweight-fit (HR [95%CI]: 1.50 [0.82-2.76]) and obese-fit (1.62 [0.87-3.01]) had a similar risk of CVD mortality. In contrast, those who were normal weight-unfit (2.04 [1.32-3.14]), overweight-unfit (2.58 [1.48-4.52]), and obese-unfit (3.35 [1.17-9.61]) demonstrated two- to three-fold greater CVD mortality risks. CONCLUSIONS: CRF is a strong predictor of CVD mortality and attenuates risks associated with overweight and obesity. These data support the inclusion of CRF as a clinical vital sign and suggest that routine measurement might enhance risk classification and improve patient care.