Depressive symptoms and the risk of incident delirium in older hospitalized adults

OBJECTIVES: To determine whether specific subsets of symptoms from the Geriatric Depression Scale (GDS), assessed at hospital admission, were associated with the incidence of delirium. DESIGN: Secondary analysis of a prospective cohort study of patients from the Delirium Prevention Trial. SETTING: General medicine service at Yale New Haven Hospital, March 25, 1995, through March 18, 1998. PARTICIPANTS: Four hundred sixteen patients aged 70 and older who were at intermediate or high risk for delirium and were not taking antidepressants at hospital admission. MEASUREMENTS: Depressive symptoms were assessed GDS, and daily assessments of delirium were obtained using the Confusion Assessment Method. RESULTS: Of the 416 patients in the analysis sample, 36 (8.6%) developed delirium within the first 5 days of hospitalization. Patients who developed delirium reported 5.7 depressive symptoms on average, whereas patients without delirium reported an average of 4.2 symptoms. Using a Cox proportional hazards model, it was found that depressive symptoms assessing dysphoric mood and hopelessness were predictive of incident delirium, controlling for measures of physical and mental health. In contrast, symptoms of withdrawal, apathy, and vigor were not significantly associated with delirium. CONCLUSION: These findings suggest that assessing symptoms of dysphoric mood and hopelessness could help identify patients at risk for incident delirium. Future studies should evaluate whether nonpharmacological treatment for these symptoms reduces the risk of delirium.