LONG BEACH, CALIF. — People with diabetes have far higher scores on a depression scale than do those without diabetes, according to a large epidemiologic study.
Furthermore, depression is associated with increased 10-year mortality in people with diabetes, but not in those without the condition.
The mortality risk goes up 54% in diabetic patients with clinical depression, compared with those without depression, after adjustment for a large number of covariates, according to Xuanping Zhang, Ph.D., of the Centers for Disease Control and Prevention, and his colleagues. Dr. Zhang presented the results at a conference on diabetes sponsored by the CDC.
The study used data collected between 1982 and 1992 by the National Health and Nutrition Examination Survey I Epidemiologic Follow-Up Survey (NHEFS). The investigators compared 558 people with diabetes to 7,063 people without the disease, and included all individuals for whom they had complete survival data and scores on the Centers for Epidemiologic Studies Depression (CES-D) scale. Scores of 16 and above indicate clinical depression, scores of 16–21 indicate moderate depression, and scores of 22 or greater indicate severe depression.
Among people with diabetes, the mean CES-D score was 26.3, compared with 15.8 among those without diabetes, a statistically significant difference.
In a multivariate analysis that adjusted for age, sex, race, marital status, education, working status, smoking status, physical activity, alcohol consumption, body mass index, self-rated health, and the presence of other serious diseases, people with diabetes who also had a CES-D score of 16 or above were 54% more likely to die over 10 years than were those with lower depression scores, a statistically significant increase in risk.
Among people who did not have diabetes, high depression scores conferred a 3% increase in mortality risk, and that increase was not statistically significant.
In an attempt to avoid the possible bias of including people with very severe disease in the analysis, the investigators also performed the analysis after excluding all those who died within 1 year of the start of the study. In that analysis, people with diabetes experienced a significant increase in the risk of mortality if their CES-D scores were 22 and above, not if they were between 16 and 21.
Dr. Zhang stated that he had no conflicts of interest regarding the study.