Study Suggests Veterans with Diabetes and Major Depressive Disorder at Significantly Increased Risk of Myocardial Infarction
Type 2 diabetes and major depressive disorder (MDD) are independent contributors to cardiovascular disease and to increased risk of myocardial infarction (MI). Although evidence suggests that depression worsens cardiovascular outcomes in patients with type 2 diabetes, previous studies were limited to two cohorts. Also, these studies have not reported on specific cardiovascular events (i.e., MI). This study sought to determine if MDD complicates the course of type 2 diabetes and is associated with increased risk of MI and mortality. Using VA data, investigators identified Veterans ages 25-80 without cardiovascular disease in FY99 and FY00 who fell into four risk groups: 1) Veterans with neither MDD nor diabetes (n=214,749); 2) Veterans with MDD alone (n=77,568); 3) Veterans with type 2 diabetes alone (n=40,953); and 4) Veterans with comorbid MDD and type 2 diabetes (n=12,679). During the follow-up period (10/00 through 9/07), investigators compared all-cause mortality and MI events among the four groups. Investigators adjusted for several covariates, including hypertension, hyperlipidemia, obesity, PTSD, anxiety disorder, nicotine dependence, and sociodemographics.
- After adjusting for sociodemographics, Veterans with comorbid MDD and type 2 diabetes were 82% more likely to experience a MI compared to Veterans without MDD and type 2 diabetes. Veterans with MDD alone were 29% more likely to have a MI, and Veterans with type 2 diabetes alone were at 33% increased risk of MI. These effects remained significant after adjusting for additional covariates (i.e., psychiatric disorders, cardiovascular risk factors and care, health service use).
- The incidence of MI increased in a step-wise fashion, from unaffected Veterans (2.6% incidence of MI) to those with depression only (3.5%) to those with diabetes only (5.9%) to Veterans with both conditions (7.4%). The incidence of all-cause mortality was 2.1%, 2.0%, 3.7%, and 3.9% for unaffected, depression only, diabetes only, and comorbid depression and diabetes.
- Veterans with PTSD, anxiety, and panic disorder were more likely to have a MI, as were Veterans with hypertension, hyperlipidemia, obesity, and nicotine dependence.
- Misclassification of covariates could have confounded results if comorbidities were under- or over-diagnosed by MDD or MI status.
- It's possible that cases of depression, i.e., less severe depression, were less likely to be diagnosed.
- Generally, VA patients have more comorbidities, which would increase the risk for MI.
Dr. Scherrer was supported by an HSR&D Career Development Award, and is part of the St. Louis VAMC. Dr. Owen is Director of HSR&D's Center for Mental Healthcare & Outcomes Research, Little Rock, AR.
Scherrer J, Garfield L, Chrusciel T, Hauptman P, Carney R, Freedland K, Owen R, True W, and Lustman P. Increased Risk of Myocardial Infarction in Depressed Patients with Type 2 Diabetes. Diabetes Care 2011 Aug;34(8):1729-34.