Interactive association of metals and Life's Essential 8 with mortality in U.S. adults: a prospective cohort study from the NHANES dataset.

Background: Life's Essential 8 (LE8) is a novel assessment of cardiovascular health (CVH) by evaluating lifestyle, and reports of the associations between LE8 and urinary metals on mortality have been very limited. This study aimed to conduct a prospective cohort study and investigate the combined effects of metals and LE8 on mortality in U.S. adults.

Methods: This study enrolled participants with complete information on urinary metals, LE8, mortality status, and confounders from the National Health and Nutrition Examination Survey (2005-2018). The Cox regression model, adaptive lasso penalized regression, and restricted cubic spline were used to analyze the individual effects of metals and LE8 on all-cause mortality. The additive and multiplicative interaction scales and quantile g-computation were used to evaluate the interaction and combined effects. Stratified analyses were performed to clarify whether metals and LE8 interacted with other variables to influence all-cause mortality.

Results: A total of 8017 participants were included in this study. The concentrations of cadmium, cobalt, lead, antimony, and thorium were greater in the low CVH group than in the high CVH group [median (µg/L): 0.29 vs. 0.19, 0.36 vs. 0.35, 0.48 vs. 0.39, 0.05 vs. 0.04, and 0.07 vs. 0.06]. The interaction between cadmium and LE8 was statistically significant, with a synergy index of 1.169 (95% CI: 1.004, 1.361). The stratified analyses showed that the interaction between age and LE8 had an impact on all-cause mortality (P for interaction = 0.004).

Conclusions: In this representative sample of the U.S. population, we found that the combined effect of cadmium, lead, thallium, and LE8 was positively associated with all-cause mortality. Furthermore, the interaction between cadmium and LE8 influenced all-cause mortality. So people should adopt healthy behaviors and reduce heavy metal exposure to minimize the risk of adverse health outcomes.