Association between excess mortality in depressive status and frailty among older adults: A population-based Kyoto-Kameoka prospective cohort study.

OBJECTIVES: Frailty has been shown to be a mediator of the risk of excess death due to depression in older adults, although this relationship has not been sufficiently investigated. Our objective was to evaluate this relationship. METHODS: We used data from 7,913 Japanese people aged≥65 years who participated in the Kyoto-Kameoka prospective cohort study and who provided valid responses to the Geriatric Depression Scale-15 (GDS-15) and the World Health Organization-Five Well-Being Index (WHO-5) in mail-in surveys. Depressive status was assessed using the GDS-15 and WHO-5. Frailty was evaluated using the Kihon Checklist. Data on mortality were collected from February 15, 2012, to November 30, 2016. We evaluated the relationship between depression and all-cause mortality risk using a Cox proportional-hazards model. RESULTS: The prevalence of depressive status assessed by GDS-15 and WHO-5 was 25.4% and 40.1%, respectively. In total, 665 deaths were recorded during a median follow-up period of 4.75 years (35,878 person-years). After adjusting for confounders, we found that depressive status assessed by the GDS-15 had a higher risk of mortality than those without it (hazard ratio [HR] 1.62, 95% confidence interval [CI] 1.38-1.91). This association was moderately weaker when adjusted for frailty (HR 1.46, 95% CI 1.23-1.73). Similar results were observed when depression was assessed with the WHO-5. CONCLUSION: Our findings suggest that the risk of excess death due to depressive status in older adults may be partially explained by frailty. This indicates a need to focus on improving frailty besides conventional depression treatments.