OBJECTIVE

To explore the association between Medicaid managed care plan enrollment and emergency department (ED) utilization.

DESIGN

Retrospective cohort analysis using administrative claims data.

PARTICIPANTS

A total of 518 982 nondisabled children 1 to 18 years of age who were Medicaid beneficiaries in calendar year 2000.

MAIN OUTCOME MEASURES

Annual visit rates per 1000 member-months and incidence rate ratios for complex and noncomplex ED visits. Medicaid beneficiaries were classified on the basis of months enrolled in managed care. Administrative claims for ED visits were classified as complex or noncomplex on the basis of procedure and diagnostic codes. Multivariate logistic regression models of the incidence rate ratios were used to compare children with varying degrees of enrollment in Medicaid man-aged care with a reference group consisting of those exclusively enrolled in Medicaid managed care.

RESULTS

Overall, 22% of children receiving Medicaid made 1 or more ED visits in 2000; 77% of ED visits were for noncomplex services. Children who spent less than half of their enrolled months in managed care used complex ED services 37% more frequently (P<.001) and noncomplex services 11% more frequently (P<.001) than those exclusively enrolled in Medicaid managed care.

CONCLUSIONS

Children with all of their Medicaid enrollment in managed care have the lowest ED utilization rates for complex and noncomplex services. These results suggest that reducing delays in managed care plan enrollment may be an effective strategy to reduce ED utilization for this population.