The mediating and joint effects of depression in the association between cardiovascular health and frailty in middle-aged and elderly people: evidence from NHANES

Objective: This study investigates the correlation between Life's Essential 8 (LE8), a cardiovascular health (CVH) metric, and frailty in middle-aged and elderly individuals in the United States, also examining how depression mediates this relationship. Methods: Participants from the NHANES 2005-2018 were analyzed for correlations between LE8 and frailty, along with the combined effects of LE8 and depression using multiple logistic regression. Dose-response relationships were assessed using restricted cubic splines (RCS), and mediation analysis explored depression's role. Sensitivity and subgroup analyses were conducted for result stability. Results: The study included 8,982 participants, with 3,103 frailty events. A higher LE8 score was significantly associated with a reduced risk of frailty, with adjusted odds ratios for the medium and high CVH groups at 0.49 (95% CI: 0.40-0.58, p < 0.001) and 0.21 (95% CI: 0.13-0.33, p < 0.001), respectively. The RCS model showed a negative dose-response relationship. No significant association was found between LE8 and frailty in the depressed population, where depression mediated 32.13% of the relationship. Conclusion: Maintaining good cardiovascular health, as measured by LE8, is key to reducing frailty risk in middle-aged and elderly individuals. This underscores the importance of cardiovascular health assessments and targeted health programs to improve quality of life.