Effects of Medicaid managed care on quality: Childhood immunizations

Background. Underimmunization is distributed unevenly across populations, concentrated among the impoverished. Managed care has stimulated the development of quality indicators such as immunization rates to assess health status of populations. Objective. To determine if enrollment in Medicaid managed care (MMC) improves quality of health care as reflected by immunization rates when compared with fee-for-service Medicaid (FFSM). Design. Prospective cohort study of infants born between May 1994 and April 1995 with a 24-month follow-up period. Setting. Urban teaching hospital and surrounding ambulatory settings. Participants. Consecutive sample of infants (n = 644) enrolled in MMC or FFSM. Ninety-two percent of eligible patients were enrolled, and 87% completed followup. Main Outcome Measure. Up-to-date immunization status. Results. Seventy-three percent of the MMC and 72.4% of the FFSM patients were up-to-date on their immunizations: relative risk 1.01, (95% confidence interval [CI] 0.87, 1.17). No differences were found in age at immunization between the MMC and FFSM groups. After adjusting for other factors in multivariate analysis, insurance status remained unassociated with immunization status: adjusted odds ratio (OR) 1.04, (95% CI: 0.90, 1.10). Factors associated with up-to-date immunization included firstborn child, OR 2.28 (95% CI: 1.45, 3.60) and adequate maternal prenatal care, OR 2.24 (95% CI: 1.44, 3.48). Variables characterizing children less likely to be adequately immunized included father living in home with child, OR 0.53 (95% CI: 0.33, 0.85) and using private office-based primary care, OR 0.39 (95% CI: 0.23, 0.63). Conclusions. Enrollment in MMC did not improve rates of immunizations when compared with FFSM.