Childhood immunization rates before and after the implementation of Medicaid managed care.

Objective: To evaluate trends in childhood immunization coverage after implementation of Medicaid managed care in Tennessee (TennCare) in 1994.

Design: Before-and-after study using the Tennessee Department of Health annual cross-sectional survey of children aged 24 months.

Patients: A mean of 1663 children per year who were randomly sampled during 1986-1999.

Main Outcome Measure: Completion rate for recommended immunizations by the age of 24 months or younger.

Results: A total of 23 044 children were included. The proportion of children continuously enrolled in Medicaid from age 1 to 24 months increased slightly with TennCare. Among children enrolled, immunization rates increased considerably before TennCare (1986-1993) and continued to increase after TennCare (1994-1999), albeit less dramatically. Immunization coverage was significantly lower for children enrolled compared with children not enrolled in fee-for-service Medicaid. Among children enrolled in fee-for-service Medicaid, black children were more likely to be inadequately immunized than white children (40% vs 26%; relative risk [RR], 1.56; 95% confidence interval [CI], 1.40-1.73). These gaps were nearly eliminated after TennCare. An increased proportion of children enrolled in TennCare received immunizations in the private sector. Among children enrolled in fee-for-service Medicaid, those receiving immunizations entirely in the private sector were more likely to have incomplete immunization status than children immunized entirely in the public sector (27% vs 21%; RR, 1.28; 95% CI, 1.20-1.37). Under TennCare and after implementation of the Vaccines for Children program in Tennessee, the difference was not significant.

Conclusions: Overall, TennCare had no discernible negative effect on immunization rates in Tennessee and perhaps contributed to decreasing the immunization gap between children enrolled and children not enrolled in Medicaid and between black and white children.