Objective: To determine whether depressive symptoms measured at baseline are associated with mortality and to describe the course of depressive symptoms and their relation to physical decline in patients over a 6-year period.
Design: Prospective cohort study conducted from 1990 through 1996.
Setting: Urban academic primary care group practice.
Patients: A cohort of 3,767 patients aged 60 years and older screened for depressive symptoms during routine office visits using the Centers for Epidemiologic Studies Depression Scale (CES-D) participated in the mortality study. A subsample of 300 patients with CES-D scores 16 or above and a subsample of 100 patients with CES-D scores less than 16 participated in the study of the course of depressive symptoms and physical decline.
Measurements and main results: Mortality by December 1995 was measured for all screened patients; reinterviewed patients completed the CES-D and the Sickness Impact Profile (SIP). The mean follow-up period was 45 months (+/- SD 12.2 months); 561 (14.9%) of the patients died by December 1995. In proportional hazards models, age, gender, race, history of smoking, serum albumin value, and an ideal body weight in the lowest 10% were significant correlates of time to death, but the baseline CES-D was not. Patients with depressive symptoms had significantly worse physical and psychosocial functioning scores on the SIP than did patients without depressive symptoms. Using the generalized estimating equation method, the strongest predictor of the current CES-D score was the patient's prior CES-D score. However, worsening physical functioning score on the SIP was also independently correlated with worse CES-D scores p < or = .001).
Conclusions: Symptoms of depression were not associated with mortality in this cohort of older adults. However, patients with depressive symptoms reported greater functional impairment than did those without depressive symptoms. Moreover, decline in physical functioning was independently correlated with a concurrent increase in depressive symptoms.