Impact of hospital volume on racial disparities in cardiovascular procedure mortality

OBJECTIVES We assessed use of low-volume hospitals by race and ethnicity for major cardiovascular procedures and determined whether hospital volume is an important factor explaining racial and ethnic differences in post-procedure mortality. BACKGROUND Low hospital volume predicts mortality for cardiovascular procedures and could be a mediator of racial and ethnic differences in procedure outcomes. METHODS We analyzed data from 719,679 hospitalizations for cardiac artery bypass grafting (CABG), percutaneous transluminal coronary angioplasty (PTCA), abdominal aortic aneurysm (AAA) repair, and carotid endarterectomy (CEA) from 1998 to 2001 using the Nationwide Inpatient Sample. We used multivariate logistic regression to assess whether race predicts use of low-volume hospitals and the relative contribution of hospital volume to racial disparity in post-procedure in-hospital mortality. RESULTS Black and Hispanic patients were more likely than white patients to receive cardiovascular procedures in low-volume hospitals. Black patients had greater risk-adjusted mortality than white patients after elective AAA repair (odds ratio [OR], 1.84; 95% confidence interval [CI], 1.20 to 2.84), CABG (OR, 1.19; 95% CI, 1.06 to 1.33), and CEA (OR, 1.56; 95% CI, 1.07 to 2.27), but not PTCA. Hispanic patients did not have higher risk-adjusted mortality than white patients. Adjusting for hospital volume did not substantially reduce the relative risk of death for black patients compared with white patients. CONCLUSIONS Black and Hispanic patients were more likely to receive cardiovascular procedures in low-volume hospitals, but hospital volume did not explain a large proportion of racial differences in post-procedure mortality. Additional research is needed to determine why black patients have increased mortality after cardiovascular procedures and how these mortality rates can be reduced.