Health Equity and Hospital Markets: Differences in the Association of Market Concentration and Quality of Care by Patient Race/Ethnicity and Payer.

Background: As hospital markets become increasingly consolidated, whether regulators should account for consolidation's impacts on health equity has become a key policy question. We assess the association of hospital market concentration with quality of care and examine differences by patient race/ethnicity and payer.

Methods: We analyzed linked 2017 American Hospital Association Annual Survey and Healthcare Cost and Utilization Project State Inpatient Data from 14 US states. Market concentration was measured using the Herfindahl-Hirschman Index (HHI) at the county level, and quality was assessed using the Prevention Quality Indicators (PQI). We assessed the relationship of HHI, patient race/ethnicity, and payer with having any PQI admission, controlling for patient and hospital characteristics. We used interaction terms for race-HHI and payer-HHI to assess differential associations of concentration by race/ethnicity and payer using linear probability models.

Results: In adjusted analyses, minoritized racial/ethnic group status and having a noncommercial primary payer were associated with a higher probability of having a PQI admission. Differences between Hispanic adults and White adults decreased in more competitive markets but increased for Asian/Pacific Islander adults versus White adults. Differences in the probability of a PQI admission between adults covered by Medicaid and self-pay/no-pay adults versus commercially insured adults increased, while differences for adults covered by Medicare decreased.

Conclusions: Hospital market concentration may have heterogeneous effects on the quality of care by patient race/ethnicity and payer. Because market concentration may impact equity, regulators should consider accounting for health equity impacts in merger reviews.