The Overlap Syndrome of Depression and Delirium in Older Hospitalized Patients

OBJECTIVES To measure the prevalence, predictors, and posthospitalization outcomes associated with the overlap syndrome of coexisting depression and incident delirium in older hospitalized patients. DESIGN Secondary analysis of prospective cohort data from the control group of the Delirium Prevention Trial. SETTING General medical service of an academic medical center. Follow-up interviews at 1 month and 1 year post-hospital discharge. PARTICIPANTS Four hundred fifty-nine patients aged 70 and older who were not delirious at hospital admission. MEASUREMENTS Depressive symptoms assessed at hospital admission using the 15-item Geriatric Depression Scale (cutoff score of 6 used to define depression), daily assessments of incident delirium from admission to discharge using the Confusion Assessment Method, activities of daily living at admission and 1 month postdischarge, and new nursing home placement and mortality determined at 1 year. RESULTS Of 459 participants, 23 (5.0%) had the overlap syndrome, 39 (8.5%) delirium alone, 121 (26.3%) depression alone, and 276 (60.1%) neither condition. In adjusted analysis, patients with the overlap syndrome had higher odds of new nursing home placement or death at 1 year (adjusted odds ratio (AOR)=5.38, 95% confidence interval (CI)=1.57-18.38) and 1-month functional decline (AOR=3.30, 95% CI=1.14-9.56) than patients with neither condition. CONCLUSION The overlap syndrome of depression and delirium is associated with significant risk of functional decline, institutionalization, and death. Efforts to identify, prevent, and treat this condition may reduce the risk of adverse outcomes in older hospitalized patients.