Survival After Coronary Artery Bypass Graft Surgery and Community Socioeconomic Status

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Abstract
Epidemiologic studies have linked adverse health outcomes to lower socioeconomic status (SES). To our knowledge, none have associated post-operative coronary artery bypass graft (CABG) surgery survival to this risk factor. To assess this, we compared post-operative survival among 771 CABG patients from different SES communities in a Southeastern state 36 months after surgery (mean follow-up = 30 months). All patients were admitted to the same tertiary care medical center for surgery in 1994 (mean age = 62; females = 214; African Americans = 13; person years of follow-up = 2,153; 36-month mortality = 8.8%). Data were extracted from the medical records of all CABG patients admitted in 1994 using the Society of Thoracic Surgeons' data-collection protocol. The study hypothesis was that patients from "disadvantaged" communities would have lower survival rates after surgery, controlling for the severity of the patient's medical condition. In this study, 181 patients were from an Appalachian county and 437 were from a medically under-served county. Post-discharge mortality was ascertained from state mortality files. Forward and backwards step-wise Cox proportional hazard regression models were used to select the most significant risk factors for mortality from 8 county-level community indicators and 32 clinical risk factor variables potentially associated with post-operative survival. Controlling for traditional risk factors for post-operative CABG survival, patients from counties with the lowest housing values have a significant increased risk of death 36 months after CABG surgery (hazard ratio [HR] = 2.46, 95% CI = 1.26-4.78, P = 0.008). Being an African American also appeared to be a significant and independent risk factor for death 36 months after surgery, as well (HR = 4.55, 95% CI = 1.37-15.11, P = 0.013). This study suggests that residence in a poor community and possibly African American status are significant and independent risk factors for mortality 36 months after CABG surgery, although the latter may have included too few cases (n = 13) to assess this effectively. Additional research is needed to determine why these associations exist and to develop specific interventions. In the mean time, closer surveillance is recommended for CABG patients admitted from lower SES communities and possibly for African American patients.