Comparing Asthma Care for Medicaid and Non-Medicaid Children in a Health Maintenance Organization

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Abstract
Objective To compare ambulatory visit patterns, rates of medication use, and emergency department and hospital utilization for children with asthma covered under Medicaid and commercial payers within the same health maintenance organization (HMO). Design Retrospective cohort study. Setting Eleven staff-model pediatric departments of an HMO. Patients A total of 1928 Medicaid and 11,007 non-Medicaid children aged 2 to 18 years with at least 1 encounter with a diagnosis of asthma between October 1, 1991, and September 30, 1996. Methods We linked patient-level data from the HMO's automated medical record system for ambulatory encounters, a claims system for emergency department and hospital care, and an automated pharmacy dispensing database. Medicaid and non-Medicaid patients were compared for all encounter types and for prescribing and dispensing of β-agonist and controller medications (inhaled corticosteroids and cromolyn sodium). Incidence rate ratios were calculated from Poisson regression models to control for age, sex, and, when appropriate, β-agonist dispensing rate. The number of refills authorized on each prescription and the fraction of medications dispensed as refills compared with new prescriptions were compared for Medicaid and non-Medicaid patients. Results Medicaid-insured children in the HMO were 1.4 times (95% confidence interval, 1.2-1.5) more likely to receive care in emergency departments and 1.3 times (95% confidence interval, 1.1-1.5) more likely to be hospitalized for their asthma compared with non-Medicaid members. Medicaid and non-Medicaid enrollees had similar yearly rates of nonurgent (1.32 vs 1.17) and urgent (0.38 vs 0.31) ambulatory visits. β-Agonists were dispensed roughly equally to Medicaid and non-Medicaid members. Although Medicaid patients were less likely to have controller medications dispensed (relative risk, 0.72; 95% confidence interval, 0.69-0.74), they were equally likely to have them prescribed. Conclusions Differences in ambulatory contact for Medicaid members do not explain the higher rates of emergency department visits and hospitalization in this population. Reasons for lower rates of dispensing of controller medications should continue to be investigated as one cause of increased morbidity for low-income children with asthma.