Depression and increased mortality in diabetes: unexpected causes of death.
OBJECTIVE
Recent evidence suggests that depression is linked to increased mortality among patients with diabetes. This study examines the association of depression with all-cause and cause-specific mortality in diabetes.


METHODS
We conducted a prospective cohort study of primary care patients with type 2 diabetes at Group Health Cooperative in Washington state. We used the Patient Health Questionnaire (PHQ-9) to assess depression at baseline and reviewed medical records supplemented by the Washington state mortality registry to ascertain the causes of death.


RESULTS
Among a cohort of 4,184 patients, 581 patients died during the follow-up period. Deaths occurred among 428 (12.9%) patients with no depression, among 88 (17.8%) patients with major depression, and among 65 (18.2%) patients with minor depression. Causes of death were grouped as cardiovascular disease, 42.7%; cancer, 26.9%; and deaths that were not due to cardiovascular disease or cancer, 30.5%. Infections, dementia, renal failure, and chronic obstructive pulmonary disease were the most frequent causes in the latter group. Adjusting for demographic characteristics, baseline major depression (relative to no depression) was significantly associated with all-cause mortality (hazard ratio [HR]=2.26, 95% confidence interval [CI], 1.79-2.85), with cardiovascular mortality (HR = 2.00; 95% CI, 1.37-2.94), and with noncardiovascular, noncancer mortality (HR = 3.35; 95% CI, 2.30-4.89). After additional adjustment for baseline clinical characteristics and health habits, major depression was significantly associated only with all-cause mortality (HR = 1.52; 95% CI, 1.19-1.95) and with death not caused by cancer or atherosclerotic cardiovascular disease (HR = 2.15; 95% CI, 1.43-3.24). Minor depression showed similar but nonsignificant associations.


CONCLUSIONS
Patients with diabetes and coexisting depression face substantially elevated mortality risks beyond cardiovascular deaths.
Lin
Elizabeth H B
EH
Group Health Research Institute, Seattle, Washington 98101, USA. lin.e@ghc.org
Heckbert
Susan R
SR
Rutter
Carolyn M
CM
Katon
Wayne J
WJ
Ciechanowski
Paul
P
Ludman
Evette J
EJ
Oliver
Malia
M
Young
Bessie A
BA
McCulloch
David K
DK
Von Korff
Michael
M
D000368:Aged; D002318:Cardiovascular Diseases / Q000401:mortality*; D002423:Cause of Death; D015897:Comorbidity; D003863:Depression / Q000175:diagnosis / Q000401:mortality*; D003924:Diabetes Mellitus, Type 2 / Q000401:mortality*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D018570:Risk Assessment; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires; D014861:Washington / Q000453:epidemiology