Volume 42 | Number 1p1 | February 2007

Abstract List

Benjamin Lê Cook


To evaluate the impact of Medicaid Managed Care (MMC) on racial disparities in access to care consistent with the Institute of Medicine (IOM) definition of racial disparity, which excludes differences stemming from health status but includes socioeconomic status (SES)‐mediated differences.

Data Sources

Secondary data from the Adult Samples of the 1997–2001 National Health Interview Survey, metropolitan statistical area (MSA)‐level Medicaid Health Maintenance Organization (MHMO) market share from the 1997 to 2001 InterStudy MSA Trend Dataset, and MSA characteristics from the 1997 to 2001 Area Resource File.

Study Design

I estimate multivariate regression models to compare racial disparities in doctor visits, emergency room (ER) use, and having a usual source of care between enrollees in MMC and Medicaid Fee‐for‐Service (FFS) plans. To contend with potential selection bias, I use a difference‐in‐difference analytical strategy and assess the impact of greater MHMO market share at the MSA level on Medicaid enrollees' access measures. To implement the IOM definition of racial disparity, I adjust for health status but not SES factors using a novel method to transform the distribution of health status for minority populations to approximate the white health status distribution.

Principal Findings

MMC enrollment is associated with lowered disparities in having any doctor visit in the last year for blacks, and in having any usual source of care for both blacks and Hispanics. Increasing Medicaid HMO market share lowered disparities in having any doctor visits in the last year for both blacks and Hispanics. Although disparities in most other measures were not much affected, black–white ER use disparities exist among MMC enrollees and in areas of high MHMO market share.


MMC programs' reduction of some disparities suggests that recent shifts in Medicaid policy toward managed care plans have benefited minority enrollees. Future research should investigate whether black–white disparities in ER use within MMC groups represent the flexibility of MMC plans to locate primary care in ERs or an inefficient delivery of care.