Social support, depression, and mortality during the first year after myocardial infarction.

Abstract

We previously reported that depression after myocardial infarction (MI) increases the long-term risk of cardiac mortality. Other research suggests that social support may also influence prognosis. This article examines the interrelationships between baseline depression and social support in terms of cardiac prognosis and changes in depression symptoms over the first post-MI year. For this study, 887 patients completed the Beck Depression Inventory (BDI) and the Perceived Social Support Scale (PSSS) at about 7 days after MI. Some 32% had BDIs > or =10, indicating mild to moderate depression. One-year survival status was determined for all patients. Follow-up interviews, including the BDI, were conducted with 89% of survivors. There were 39 deaths (35 cardiac). Elevated BDI scores were related to cardiac mortality (P=0.0006), but PSSS scores and other measures of social support were not. There was a significant interaction between depression and the PSSS (P=0. 016). The relationship between depression and cardiac mortality decreased with increasing support. Furthermore, residual change score analysis revealed that among 1-year survivors who had been depressed at baseline, higher baseline social support was related to more improvement in depression symptoms than expected. Post-MI depression is a predictor of 1-year cardiac mortality, but social support is not directly related to survival. However, very high levels of support appear to buffer the impact of depression on mortality. Furthermore, high levels of support predict improvements in depression symptoms over the first post-MI year in depressed patients. High levels of support may protect patients from the negative prognostic consequences of depression because of improvements in depression symptoms.