The finding of a significant black-white ER use disparity among MMC enrollees and in high MHMO areas merits further research.
Increased MHMO market share within an MSA reduced disparities in having a doctor visit in the last year among black and Hispanic Medicaid enrollees.
Differencing using the MSA-level variable assesses the impact of increased MHMO market share on different races, but assumes that individuals in different racial/ethnic subgroups exhibit identical selection behaviors in response to MHMO market share.
Determining causal inference of MSA-level MHMO market share requires that this variable not be correlated with other predictors of racial disparities in access and utilization.
Reduced disparities in having a doctor visit in the last year for black and Hispanic enrollees living in high MHMO market share areas, and an association of MMC enrollment and the reduction of blacks and Hispanic disparities in having a usual source of care, suggest that managed care improved access to care for minorities.