evidence: In terms of clinical quality, we found no difference for the primary outcome of ambulatory care–sensitive hospitalizations. Among secondary outcomes, 5 measures favored Marketplace coverage (though 1 was of minimal clinical relevance, a 1 percentage-point difference in flu vaccination), 1 measure favored Medicaid, and the rest (6 of 12) showed no significant differences. Lower rates of mammography and chlamydia testing in Medicaid are consistent with a previous analysis, though that study lacked individual-level measures of socioeconomic status.36 Results for chronic disease measures varied, with higher rates of hemoglobin A1c and urine microalbumin testing among diabetic patients in Marketplace coverage but higher rates of β-blocker prescription for coronary artery disease in Medicaid. Our finding of similar rates of low-value care in both insurance types was consistent with a prior study.26 Overall, our results suggest a mixed picture on quality, with a plurality of secondary outcomes favoring private coverage, but with more than half of the primary and secondary measures showing no significant differences, similar to a prior quasi-experimental study comparing Kentucky’s Medicaid expansion to Arkansas’ private insurance expansion for low-income adults.34