Association of Coexisting Diabetes and Depression With Mortality After Myocardial Infarction

Association of Coexisting Diabetes and Depression With Mortality After Myocardial Infarction

Diabetes Care March 2012 vol. 35no. 3 503-508

OBJECTIVE Diabetes and depression are both linked to an increased mortality risk after myocardial infarction (MI). Population-based studies suggest that having both diabetes and depression results in an increased mortality risk, beyond that of having diabetes or depression alone. The purpose of this study was to examine the joint association of diabetes and depression with mortality in MI patients.

RESEARCH DESIGN AND METHODS Data were derived from two multicenter cohort studies in the Netherlands, comprising 2,704 patients who were hospitalized for MI. Depression, defined as a Beck Depression Inventory score ≥10, and diabetes were assessed during hospitalization. Mortality data were retrieved for 2,525 patients (93%).

RESULTS During an average follow-up of 6.2 years, 439 patients died. The mortality rate was 14% (226 of 1,673) in patients without diabetes and depression, 23% (49 of 210) in patients with diabetes only, 22% (118 of 544) in patients with depression only, and 47% (46 of 98) in patients with both diabetes and depression. After adjustment for age, sex, smoking, hypertension, left ventricular ejection fraction, prior MI, and Killip class, hazard ratios for all-cause mortality were 1.38 (95% CI 1.00–1.90) for patients with diabetes only, 1.39 (1.10–1.76) for patients with depression only, and as much as 2.90 (2.07–4.07) for patients with both diabetes and depression.

CONCLUSIONS We observed an increased mortality risk in post-MI patients with both diabetes and depression, beyond the association with mortality of diabetes and depression alone.

COMMENTS: More bad news for patients with co-existing type 2 diabetes and depression.  This is an important finding because the prevalence of depression in type 2 diabetes is between 10-20% and the lifetime incidence is nearly 100%.  What an epidemiologic study like this will not tell us, of course, is whether the myocardial infarction in type 2 diabetes was causally related to the depression or the depression was a result of the infarct.  It also does not tell us what the causes of death were over the 6.2-year follow up.  Finally it does not tell us whether or not the treatment of depression reduced the mortality.  So the action item for the clinician is to be aware of depression in such patients and its effect on mortality.  Personally I use the WHO-5 depression scale rather than the Beck Depression Inventory as a screening instrument.  How do you screen for depression?  Do you screen all patients?