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

Background-We previously reported that depression after myocardial infarcti on (MI) increases the long-term risk of cardiac mortality. Other research s uggests that social support may also influence prognosis. This article exam ines the interrelationships between baseline depression and social support in terms of cardiac prognosis and changes in depression symptoms over the f irst post-MI year. Methods and Results-For this study, 887 patients completed the Beck Depress ion Inventory (BDI) and the Perceived Social Support Scale (PSSS) at about 7 days after MI. Some 32% had BDIs greater than or equal to 10, indicating mild to moderate depression. One-year survival status was determined for al l 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 measure s of social support were not. There was a significant interaction between d epression and the PSSS (P=0.016). The relationship between depression and c ardiac mortality decreased with increasing support, Furthermore, residual c hange score analysis revealed that among 1-year survivors who had been depr essed at baseline, higher baseline social support was related to more impro vement in depression symptoms than expected. Conclusions-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. F urthermore, high levels of support predict improvements in depression sympt oms over the first post-MI year in depressed patients. High levels of suppo rt may protect patients from the negative prognostic consequences of depres sion because of improvements in depression symptoms.