Body mass index variability and its role in cardiovascular disease risk stratification: a large cohort study

Although body mass index (BMI) is a well-established predictor of cardiovascular disease (CVD), the prognostic significance of intra-individual BMI variability remains uncertain. This study investigated the association between long-term BMI variability and the risk of CVD, including stroke and coronary artery disease (CAD). We conducted a retrospective cohort study of adults aged ≥ 40 years who underwent three or more repeated health examinations from 2002 to 2011 at a single center in South Korea. BMI variability was quantified using the coefficient of variation and categorized into tertiles. Participants were followed for incident CVD events (stroke or CAD) from 2012 to 2021. Cox proportional hazards models estimated hazard ratios and 95% confidence intervals for CVD outcomes, adjusting for demographic, clinical, and behavioral covariates, with subgroup analyses conducted according to baseline BMI categories. Among the 80,941 participants, higher BMI variability was associated with significantly lower risks of CVD (HR, 0.90; 95% CI 0.85–0.96) and CAD (HR, 0.89; 95% CI 0.83–0.95) in fully adjusted models, while no significant association was observed for stroke. The inverse association between BMI variability and CVD or CAD was most prominent among participants with a baseline BMI ≥ 23.0 kg/m2. These findings suggest that higher BMI variability is associated with lower CVD risk in this cohort, particularly among individuals with elevated baseline BMI. This association should be interpreted with caution and does not establish causality, but may reflect underlying behavioral or clinical factors related to cardiovascular risk.