Mediation effect analysis of lipoprotein levels on BMI and cardiovascular outcomes in patients with heart failure

Among heart failure patients with obesity, the prognosis is better than those with normal weight, a phenomenon known as the obesity paradox. However, it is unclear whether lipoprotein levels play a mediating role in the machine of the obesity paradox. The study included 1663 heart failure patients hospitalized from January, 2019 through August, 2022. Kaplan-Meier survival analysis and Log-rank tests were performed for three endpoints in order to determine cumulative event-free survival. We investigated the correlation between Body Max Index (BMI) and outcomes by multifactorial Cox models. Mediation analysis was applied to study the presence and magnitude of mediation effects of triglyceride, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, apolipoprotein A1 and apolipoprotein B, with the association between BMI and endpoints. In MACCEs, the median follow-up period was 679 days. In Cox model, compared with the underweight group, a high BMI level was significantly associated with lower all-cause mortality (HR=0.47, 95%CI 0.31~0.69, p