During the study, the team tracked 10,704 Medicare beneficiaries with diabetes who were enrolled in a disease management program in Florida. T
They were surveyed at the start of the study with a health assessment questionnaire. Evidence of depression among members of the group came from physician diagnosis, patient reports of having a prescription for an antidepressant in the year before the survey, or patient answers to a brief screening test.
For the next two years, the research team recorded the death and cause of death of participants through bi-monthly checks of Medicare claims and eligibility files, or from phone calls with the participants' families.
A total of 12.1 percent of participants who had both disorders died during that period. Among those without depression, 10.4 percent died.
The study led by Dr. Wayne Katon, professor of psychiatry and behavioural sciences at the University of Washington (UW), also found that the patients who had been treated with one or more antidepressant medications in the year before the study had a 24 percent increased risk of mortality, compared to non-depressed participants.
The findings are published in the October 2008 Journal of General Internal Medicine.