Depressive symptoms, healthcare utilization, and mortality in older adults: The modifying role of frailty

Abstract

Background Late-life depression is common and shapes healthcare use, but its consequences may not be uniform. Prior studies quantified the combined risk of depression and frailty; whether frailty modifies the depression-outcome association across the care spectrum remains untested. Methods In a dynamic person-interval cohort from the Korean Longitudinal Study of Aging (exposures 2014-2022; outcomes ascertained through 2024), community-dwelling adults aged >= 65 years were followed over 2-year intervals. Exposures were depressive symptoms (per 5-point 10-item CES-D increase) and frailty (robust, prefrail, frail). Effect modification on outpatient visits, inpatient admission, and mortality (long-term care hospital [LTCH] admission, exploratory) was tested on multiplicative (Holm-Bonferroni-adjusted) and additive (relative excess risk due to interaction [RERI]) scales. Results Among 21,291 person-intervals from 6104 participants, depressive symptoms were associated with fewer outpatient visits regardless of frailty (no evidence of modification). For admission, each 5-point increase carried higher odds in frail (adjusted odds ratio, 1.25 [95% CI, 1.18-1.33]) but not robust participants (1.00; Holm-adjusted P < .001; RERI for CES-D10 >= 10, 0.61). A similar pattern occurred for mortality (frail, 1.31 vs robust, 1.00; P = .004; RERI, 1.25), though specification-sensitive. No clear modification emerged for LTCH admission. Limitations Utilization was self-reported over a 2-year recall; a standardized cognitive measure was unavailable; and the CES-D screens symptoms rather than diagnosing major depression. Conclusions Depressive symptoms were associated with lower ambulatory care regardless of frailty but with higher hospitalization primarily in frail individuals-beyond simple joint risk-and less consistently with mortality, marking frail older adults with depressive symptoms as a high-risk group.