The impact of competition in hospital markets on disparities in procedure use: The case of CABG surgery for AMI patients

Prior research on the effects of hospital market structure on quality of care has systematically assumed that the effects of competition were homogeneous across population groups. Most of the research has thus focused on the effects of competition at the aggregate level, but we do not know whether racial/ethnic and gender disparities in health outcomes vary with the level of competition in hospital markets. I use data from the 2003 NIS core file linked with information on hospital characteristics from the 2003 AHA survey and information on hospital market structure from the HCUP HMS file to address this gap in the literature. I identify the determinants of procedure use for coronary artery bypass graft (CABG) in different levels of hospital market competition and test whether the impact of competition on patient outcomes varies with the race/ethnicity and the gender of a patient. Using event history analysis (proportional hazards models) to control for patient and hospital characteristics, I found that racial disparities in CABG rates among male patients were reduced (though not eliminated) by increased competition in hospital markets. Among women, the extent of racial disparities in CABG use did not differ by level of hospital market competition. Use of CABG surgery was generally higher in low competition market, except for black male patients. Controlling for unobserved heterogeneity with physician fixed effects models, differences in racial/ethnic disparities in CABG use in different types of markets were similar to models without physician characteristics. The interaction between patient's race and hospital market competition dropped out of significance in specifications that included physician effects. This may however be due to limited sample sizes available for analyses analysis based on stratified proportional hazards models.;Market level factors may be an important determinant of racial/ethnic and gender disparities in healthcare. Findings from the study indicate that regulations preventing the establishment of monopolies in hospital markets may be beneficial for patient health outcomes, and possibly racial/ethnic disparities in patient health outcomes. I discuss several limitations to the study, and suggest future research on the effects of hospital market competition on racial/ethnic and gender disparities in healthcare.