The mediating effect of 24-h time-use behaviors on the relationship between depression and mortality: A compositional mediation analysis for survival outcomes

A compositional mediation model of survival outcomes was established to explore whether 24-h time-use behaviors mediate the relationship between depression and mortality. 4137 adults from the National Health and Nutrition Examination Survey (NHANES 2005–2006) were followed up to 2019. Cox proportional hazards regression model was used to estimate the total effect of depression on mortality. Compositional data analysis was used to examine the relationship between 24-h time-use compositions and mortality. Furthermore, we constructed a compositional mediation model for survival outcomes to investigate the mediating effect of 24-h time-use behaviors on depression and mortality. Compared with participants without depression, depressive patients had a significantly higher risk of overall mortality (HR = 1.49, 95 % CI: 1.25,1.79), cardiovascular disease -specific mortality (HR =1.89, 95 % CI: (1.37,2.63)) and mortality from causes other than cardiovascular disease or cancer (HR = 1.62, 95 % CI: (1.25,2.08)). Physical activity, especially moderate-to-vigorous physical activity, significantly mediated the relationship between depression and all-cause and CVD-specific mortality. Despite being a cohort study, the exposure and mediatiors were measured at the baseline. Further research is necessary to require a temporal order between the exposure and mediating variables. Our findings indicate that 24-h time-use behaviors link depression to mortality. In particular, increasing the time spent on physical activity can reduce the risk of death in patients with depression. This finding provides potential interventions for reducing the risk of death in patients with depression.