The association between obesity indicators and mortality among individuals with hyperlipidemia: evidence from the NHANES 2003-2018

Background Obesity is linked to a variety of metabolic issues, with hyperlipidemia being a crucial adjustable risk element for cardiovascular diseases (CVD). However, the connection between indicators of obesity with overall and CVD mortality in American adults with hyperlipidemia remains unknown. Methods This research employed an extensive cohort drawn from the National Health and Nutrition Examination Survey (NHANES) (2003-2018). Hyperlipidemia was identified through either elevated lipid profiles or self-reported utilization of lipid-reducing medications. Obesity indicators (weight-adjusted waist index (WWI), waist-to-height ratio (WHtR), body mass index (BMI)) were evaluated by physical measurement data. Weighted Cox regression models and restricted cubic splines (RCS) were employed to assess the potential links between obesity indicators and mortality outcomes. Results were further validated through subgroup analyses to ensure robustness and reliability. The receiver operating characteristic (ROC) curve was utilized to evaluate the prognostic capability of obesity indicators for mortality. Results This cohort study included data from 12,785 participants with hyperlipidemia. Over an average follow-up period of 8.4 years, a total of 1,454 deaths were documented, 380 of which were related to heart diseases. Cox analysis manifested that, after adjusting covariates, increased WWI was linked to a higher likelihood of overall and CVD mortality (both P < 0.05). RCS analysis illustrated that BMI and WHtR had U-shaped relationships with the overall and CVD mortality. Conversely, a linear positive association was uncovered between WWI and mortality (both P > 0.05 for nonlinearity). Age, alcohol consumption and chronic kidney disease had modifying effects on the relationship between WWI and total mortality among those with hyperlipidemia. The area under ROC indicated that WWI was more effective than for BMI and WHtR in predicting overall and CVD deaths. Conclusions In US adults with hyperlipidemia, the connection between BMI, WHtR, with overall and CVD mortality followed a U-shaped pattern, whereas a positive linear correlation was identified between WWI and mortality. WWI has superior predictive capability for the prognosis of individuals with hyperlipidemia compared to BMI and WHtR. These findings provide new insights and targets for the health management of individuals affected by hyperlipidemia.