Evaluation of STEMI Regionalization on Access, Treatment, and Outcomes Among Adults Living in Nonminority and Minority Communities

IMPORTANCE: Cardiac care regionalization, specifically for patients with ST-segment elevation myocardial infarction (STEMI), has been touted as a potential mechanism to reduce systematic disparities by protocolizing the treatment of these conditions. However, it is unknown whether such regionalization arrangements have widened or narrowed disparities in access, treatment, and outcomes for minority communities. OBJECTIVE: To determine the extent to which disparities in access, treatment, and outcomes have changed for patients with STEMI living in zip codes that are in the top tertile of the Black or Hispanic population compared with patients in nonminority zip codes in regionalized vs nonregionalized counties. DESIGN, SETTING, AND PARTICIPANTS: This cohort study used a quasi-experimental approach exploiting the different timing of regionalization across California. Nonpublic inpatient data for all patients with STEMI from January 1, 2006, to October 31, 2015, were analyzed using a difference-in-difference-in-differences estimation approach. EXPOSURE: Exposure to the intervention was defined as on and after the year a patient’s county was exposed to regionalization. MAIN OUTCOMES AND MEASURES: Access to percutaneous coronary intervention (PCI)–capable hospital, receipt of PCI on the same day and at any time during the hospitalization, and time-specific all-cause mortality. RESULTS: This study included 139 494 patients with STEMI; 61.9% of patients were non-Hispanic White, 5.6% Black, 17.8% Hispanic, and 9.0% Asian; 32.8% were women. Access to PCI-capable hospitals improved by 6.3 percentage points (95% CI, 5.5 to 7.1 percentage points; P < .001) when patients in nonminority communities were exposed to regionalization. Patients in minority communities experienced a 1.8–percentage point smaller improvement in access (95% CI, −2.8 to −0.8 percentage points; P < .001), or 28.9% smaller, compared with those in nonminority communities when both were exposed to regionalization. Regionalization was associated with an improvement to same-day PCI and in-hospital PCI by 5.1 percentage points (95% CI, 4.2 to 6.1 percentage points; P < .001) and 5.0 percentage points (95% CI, 4.2 to 5.9 percentage points; P < .001), respectively, for patients in nonminority communities. Patients in minority communities experienced only 33.3% and 15.1% of that benefit. Only White patients in nonminority communities experienced mortality improvement from regionalization. CONCLUSIONS AND RELEVANCE: Although regionalization was associated with improved access to PCI hospitals and receipt of PCI treatment, patients in minority communities derived significantly smaller improvement relative to those in nonminority communities.