The relationship between the trajectory of body mass index changes over a long lifecycle and the risk of all-cause mortality in patients with cardiovascular disease: NHANES longitudinal cohort study

Background The relationship between changes in body mass index (BMI) over a long lifecycle and the risk of all-cause mortality among patients with cardiovascular disease (CVD) remains understudied. This study aims to investigate the association between BMI changes (from age 25 to after 50) and the risk of all-cause mortality in CVD patients. Methods This study leveraged data from the National Health and Nutrition Examination Survey (NHANES) 2001–2018 and the National Death Index (NDI) to construct a longitudinal cohort. Employing weighted multivariable Cox regression and Restricted Cubic Spline (RCS) analyses, we evaluated both the linear and nonlinear associations between BMI (at age 25 and after 50), its changes, and the risk of all-cause mortality among patients with CVD. Results A total of 2304 CVD patients were included in this study. During a median follow-up of 68 months, 774 participants died. The lowest risk of mortality was observed when BMI was 19.61 at age 25 and 26.55 after the age of 50. The impact of BMI change between these two time points on all-cause mortality risk exhibited a U-shaped relationship Specifically, when the change in BMI exceeded 8.27, it was positively associated with all-cause mortality risk [HR = 1.16, 95%CI=(1.00, 1.33)]. Conclusion Among CVD patients, changes in BMI during the long-life span were nonlinearly associated with the risk of all-cause mortality. When formulating weight management strategies in the long life cycle based on BMI, individualized approaches should be taken rather than blindly emphasizing weight loss.