To the Editor.
—The data of Frasure-Smith et al1 identifying mental depression as a major determinant of cardiac death after MI are very impressive and will no doubt have a large impact. However, I have three points.First, the study found a fivefold higher mortality rate among depressed MI survivors. I think that this study may suffer from some selection bias. The two groups were tested for symmetry of covariates. However, their psychosocial factors before the MI were not taken into account and were probably largely asymmetric. I assume that many of the patients who were depressed after the MI were so before, and that their depression was, in fact, so severe that it led to the MI in the first place. Therefore, these are a selected group of severely depressed people and their mortality rates may not be representative for mortality rates of survivors of MI who were
Cleophas TJM. Depression and Survival Following Myocardial Infarction. JAMA. 1994;271(14):1081. doi:10.1001/jama.1994.03510380036030