EXPRESS: The mediating role of depressive symptoms between asthma and risk of all-cause mortality

This study aimed to evaluate the mediating role of depressive symptoms on asthma and the risk of mortality. We employed the distribution of product method to test whether depressive symptoms had a mediating effect on the association between asthma and risk of mortality. The 95% confidence interval (CI) of the distribution of product was obtained. A weighted multivariable Cox regression model was used to analyze the correlation between asthma and all-cause mortality and verify the mediating impact of depressive symptoms on the association between asthma and risk of mortality. Odds ratio (OR), hazard ratio (HR), 95%CI, and percentage mediated were effect size. The mean follow-up time of all participants was 99.45 months. The percentage of subjects with depressive symptoms in the death group was 23.67%, and in the alive group was 16.65%. The risk of depressive symptoms was heightened in people with asthma (OR=2.03, 95%CI: 1.82-2.27). Asthma was found to increase the risk of all-cause mortality (OR=1.18, 95%CI: 1.06-1.31). The distribution of product for the mediating effect of depressive symptoms on the relationship between asthma and all-cause mortality was 0.08 (95% CI: 0.01-0.16), with the 95% CI not including 0, indicating that depressive symptoms played a mediating role in this relationship. The indirect effect was 1.09(95%CI: 1.01-1.18), and the percentage of asthma's impact on all-cause mortality mediated by depressive symptoms was 11.11%. Depressive symptoms mediated the association of asthma and all-cause mortality.