Major Depression and Coronary Artery Disease

Kendler et al¹ report a bidirectional relationship between major depression (MD) and coronary artery disease (CAD), albeit a modest one with an odds ratio of 1.3. We use the publication of Kendler et al¹ to observe that, in our opinion, significant limitations compromise all or most studies of such comorbidity, namely the imprecise and subjective nature of tools used to assess MD contrasted with the more precise and objective methods used to identify CAD. In the case of CAD, information was obtained from 2 reliable national registers and included diagnoses, cardiac surgical procedures, and cause of death, as applicable. In striking contrast, MD was assessed by telephone interviews using the World Health Organization Composite International Diagnostic Interview Short Form. In this method, no information was obtained about treatment(s) for depression, hospitalization, absenteeism from work or other role performance, nor complications such as suicide attempt or alcohol or other substance abuse. We do not even know if patients suspected of having MD and seeking treatment are the same patients identified with MD in surveys such as those conducted by Kendler and associates.¹