Reflections on depression as a cardiac risk factor.

Objective: Major North American cardiology organizations do not currently list depression among the officially recognized cardiac risk factors, yet many behavioral medicine specialists believe depression to be an important risk. We wondered what was missing from the available data.

Methods: The Medline, Current Contents, and PsychInfo databases were used to perform a systematic review of the literature linking depression and depressive symptoms with cardiac disease outcomes. Because of previous reviews, we paid particular attention to publications from 2001 to 2003.

Results: We identified 21 etiologic and 43 prognostic publications that had prospective designs, used recognized measures of depression, and included objective outcome measures. We also identified 79 review articles. In addition to issues of sample size, sample characteristics, and timing of measures, we noted heterogeneity in the definitions of depression, frequent repeat publications from the same data sets, heterogeneity of outcome measures, a variety of approaches for covariate selection, and a preponderance of review articles, all factors that cannot help to convince skeptics.

Conclusions: Despite these issues, the bulk of the data from prospective studies with recognized indices of depression and objective outcome measures is supportive of depression as a cardiac risk factor.