Depression and 5-year mortality in patients with acute myocardial infarction: analysis of the IDACC database

Symptoms of depression are highly prevalent and persistent following myocardial infarction (MI). Whether depression is a risk factor for long-term mortality following MI remains controversial. The present study aimed to determine whether depression during hospitalisation for acute MI (AMI) predicted 5-year all-cause or cardiac mortality.

This study utilised the Identifying Depression as a Comorbid Condition (IDACC) database of 337 hospitalised patients with AMI. Depressive symptoms were assessed using the Center for Epidemiologic Studies Depression scale (CES-D). Data were linked to a government administrative death registry to determine 5-year mortality. Survival data were analysed using Cox's proportional hazards model.

The mean age during AMI hospitalisation was 59 years ± 12, 74% of patients were men and depression (CES-D ≥ 16) was present in 132 patients (39.3%). The 5-year all-cause mortality rate was 10.4% (35 deaths) and the cardiac mortality rate was 6.5% (22 deaths). When depression was defined as a dichotomous variable, moderate to severe depression (defined by CES-D ≥ 27) at the time of AMI was associated with all-cause mortality (hazard ratio 2.54, 95% confidence interval 1.03 to 6.28; p = 0.04) but not cardiac mortality. However, when depression was defined by three categories (no depression CES-D < 16, mild depression CES-D 16-26, moderate to severe depression CES-D ≥ 27), it was not found to predict mortality. In addition, perceived social support was a predictor of all-cause and cardiac mortality in AMI patients.

Our results indicate that the relationship between mortality and depression severity is not linear and that the association only becomes evident when the severity reaches a threshold level of CES-D ≥ 27, consistent with major depression. Low power may have influenced the finding of a lack of association between depression and cardiac mortality.