Comorbid depression in type 2 diabetic males is significantly associated with a range of adverse heart events, a study has shown. Treatment with antidepressant medications, however, appears to substantially moderate this link, according to Dr. Thomas S. Higgins Jr. of the University of Louisville (Ky.) and colleagues.
Previous studies have shown an increased prevalence of depression among type 2 diabetics. Because diabetes is a known risk factor for heart disease and because depressive symptoms have been associated with an increased prevalence of comorbid myocardial infraction, hypertension, and angina in certain diabetic populations, Dr. Higgins and colleagues sought to determine whether comorbid depression and diabetes together produce greater cardiac health risk than either condition alone.
The investigators reviewed data for 8,185 males over age 40 collected from the electronic medical record system of a Midwestern Veterans Affairs Medical Center (VAMC). All of the subjects had a history of type 2 diabetes and had visited the VAMC within the previous 6 years (Diabetes Res. Clin. Pract. 2006, Jul. 31 [Epub ahead of print]).
Of the 8,815 subjects, 691 had been diagnosed with depression. These individuals tended to be younger and unmarried relative to their nondepressed counterparts, and they were more likely to have a history of smoking and non-heart-related chronic diseases. More than half (57.2%) had been prescribed antidepressant medication.
A total of 2,358 subjects had been diagnosed with heart disease, such as coronary artery disease or myocardial infarction, or had undergone a heart disease-related procedure, such as angioplasty or coronary artery bypass graft (CABG). Subjects in this “adverse heart event” category were more likely to have diagnoses of depression, chronic obstructive pulmonary disease, stroke, hypertension, prostate cancer, and hyperlipidemia than subjects without prior heart events. They were also more likely to be white and to have been prescribed antidepressants.
The investigators used odds ratios to examine the link between depression status and the occurrence of each adverse heart event, and they used logistic regression to control for potential confounding variables. They performed an additional logistic regression analysis in which antidepressant medication status was included as a confounding variable, to evaluate antidepressant prescription status as a moderating variable and the interaction between depression and antidepressant status.
After adjustment for all significant confounders, the analysis demonstrated significant positive associations between depression and any adverse heart event and with each individual heart event except CABG. There was also a significant interaction between depression and antidepressant prescription status for any adverse heart event, coronary artery disease, and angioplasty. After adjustment for this interaction, the associations between depression and adverse cardiac events were no longer significant among the subjects who had been prescribed antidepressant medications; however, they remained significant for those not given antidepressants, the authors wrote.
Although the findings suggest that depressed diabetics are at increased risk for heart disease and that treating depression in diabetics may reduce this increased risk, the study has several limitations, the authors noted. Its cross-sectional design precludes determining which condition presented first and thus cannot be used to suggest a causal relationship. Also, there may be inconsistencies in data quality across the study population, the study may have missed patients who died at the time of their first adverse cardiac event or who received treatment at another hospital, and there is no information on level and duration of antidepressant use. Finally, the inclusion of only older male patients from one center limits the generalizability of the data, they said.