Abstract
BACKGROUND: The impact of the changes in the obesity status on mortality has not been established; thus, we investigated the long-term influence of body fat (BF) changes on all-cause deaths and cardiovascular outcomes in a general population. METHODS: A total of 8374 participants were observed for 12 years. BF was measured at least two times using a bioimpedance method. The causes of death were acquired from the nationwide database. A major adverse cardiovascular event (MACE) was defined as a composite of myocardial infarction, coronary artery disease, stroke, and cardiovascular death. Standard deviations (SDs) were derived using a local regression model corresponding to the time elapsed between the initial and final BF measurements (SD(T)) and were used to standardize the changes in BF (ΔBF/SD(T)). RESULTS: The incidence rates of all-cause death, cardiovascular death, and MACE were the highest in the participants with ΔBF/SD(T) <-1 and lowest in the participants with ΔBF/SD(T) ≥1. Multivariate Cox proportional hazard models adjusted for relevant covariates, including baseline obesity and physical activity, showed that the risks of all-cause deaths (hazard ratio [HR] 0.58; 95% confidence intervals [CI] 0.53-0.64), cardiovascular deaths (HR 0.63; 95% CI 0.51-0.78) and MACEs (HR 0.68; 95% CI 0.62-0.75) decreased as ΔBF/SD(T) increased. Subgroup analyses showed that existing cardiovascular diseases weakened the associations between higher ΔBF/SD(T) and better outcomes, while high physical activity and exercise did not impact the associations. CONCLUSION: Increasing BF was associated with a lower risk of all-cause death, cardiovascular death, and MACE in the general population.Key messagesIncreasing body fat is associated with a lower risk of all-cause death, cardiovascular death, and major cardiovascular adverse events in a low-risk ageing general population, independently of physical activity, underlying cardiovascular disease burden, changes in muscle mass, and baseline obesity status.Fatness measured at baseline requires adjustment for the changes in fatness during the follow-up to reveal its impact on the clinical outcomes.