Depressive symptoms are not independent predictors of mortality, according to data from a national sample of 3,617 adults.
The findings of previous studies of associations between depressive symptoms and mortality have been inconsistent, and few of these studies have used population-based samples, said Susan A. Everson-Rose, Ph.D., of Rush University Medical Center, Chicago, and her colleagues (Psychosom. Med. 2004;66:823–30).
The investigators selected noninstitutionalized adults aged 25 years and older who were participating in an ongoing, longitudinal study called Americans' Changing Lives.
A total of 542 deaths occurred during 7.5 years of follow-up. Each increase of 1 standard unit on the Center for Epidemiological Studies Depression scale (CES-D) predicted a 21% increase in death from any cause after age, race, and gender were adjusted for. However, no excess risk of mortality was associated with CES-D scores in a fully adjusted model that included demographics, education, income, behavioral risk factors, and three indicators of health status (hypertension, functional impairment, and life-threatening conditions).
The physical complaints of patients with depression often resemble symptoms of other health problems, and distinguishing between clinical depression and poor physical health can be difficult, the investigators said.
Patients with scores in the highest quintile on the CES-D had an 85% greater risk of death from any cause, compared with participants with the lowest CES-D scores, but no other quintiles showed an increased mortality risk, Dr. Everson-Rose and her associates reported.
Depressive symptoms were not significantly associated with mortality risk in a healthy subgroup of 2,833 adults (with 306 deaths) who reported good or excellent health at baseline. In addition, depressive symptoms were not associated with increased mortality risk in patients without functional impairments at baseline.
Although depressive symptoms were associated with greater physical impairment over time after demographics, socioeconomic status, and baseline physical impairment were controlled for, the CES-D does not measure clinical depression, which has been studied as a possible link to mortality and cardiovascular health, the investigators noted.