Depression Following Myocardial Infarction: Impact on 6-Month Survival

Abstract

OBJECTIVE: To determine if the diagnosis of major depression in patients hospitalized following myocardial infarction (MI) would have an independent impact on cardiac mortality over the first 6 months after discharge. DESIGN: Prospective evaluation of the impact of depression assessed using a modified version of the National Institute of Mental Health Diagnostic Interview Schedule for major depressive episode. Cox proportional hazards regression was used to evaluate the independent impact of depression after control for significant clinical predictors in the data set. SETTING: A large, university-affiliated hospital specializing in cardiac care, located in Montreal, Quebec. PATIENTS: All consenting patients (N = 222) who met established criteria for MI between August 1991 and July 1992 and who survived to be discharged from the hospital. Patients were interviewed between 5 and 15 days following the MI and were followed up for 6 months. There were no age limits (range, 24 to 88 years; mean, 60 years). The sample was 78% male. PRIMARY OUTCOME MEASURE: Survival status at 6 months. RESULTS: By 6 months, 12 patients had died. All deaths were due to cardiac causes. Depression was a significant predictor of mortality (hazard ratio, 5.74; 95% confidence interval, 4.61 to 6.87; P = .0006). The impact of depression remained after control for left ventricular dysfunction (Killip class) and previous MI, the multivariate significant predictors of mortality in the data set (adjusted hazard ratio, 4.29; 95% confidence interval, 3.14 to 5.44; P = .013). CONCLUSION: Major depression in patients hospitalized following an MI is an independent risk factor for mortality at 6 months. Its impact is at least equivalent to that of left ventricular dysfunction (Killip class) and history of previous MI. Additional study is needed to determine whether treatment of depression can influence post-MI survival and to assess possible underlying mechanisms.