Comparing asthma care for medicaid and non-medicaid children in a health maintenance organization

Objective: To compare ambulatory visit patterns, rates of medication use, a nd emergency department and hospital utilization for children with asthma c overed under Medicaid and commercial payers within the same health maintena nce organization (HMO). Design: Retrospective cohort study Setting: Eleven staff-model pediatric departments of an HMO. Patients: A total of 1928 Medicaid and 11007 non-Medicaid children aged 2 t o 18 years with at least 1 encounter with a diagnosis of asthma between Oct ober 1, 1991, and September 30, 1996. Methods: We linked patient-level data from the HMO's automated medical reco rd system for ambulatory encounters, a claims system for emergency departme nt and hospital care, and an automated pharmacy dispensing database. Medica id and non-Medicaid patients were compared for all encounter types and for prescribing and dispensing of P-agonist and controller medications (inhaled corticosteroids and cromolyn sodium). Incidence rate ratios were calculate d from Poisson regression models to control for age, sex, and, when appropr iate, beta-agonist dispensing rate. The number of refills authorized on eac h prescription and the fraction of medications dispensed as refills compare d with new prescriptions were compared for Medicaid and non-Medicaid patien ts. Results: Medicaid-insured children in the HMO were 1.4 times (95% confidenc e interval, 1.2-1.5) more likely to receive care in emergency departments a nd 1.3 times (95% confidence interval, 1.1-1.5) more likely to be hospitali zed for their asthma compared with non-Medicaid members. Medicaid and non-M edicaid enrollees had similar yearly rates of nonurgent (1.32 vs 1.17) and urgent (0.38 vs 0.31) ambulatory visits. P-Agonists were dispensed roughly equally to Medicaid and non-Medicaid members. Although Medicaid patients we re less likely to have controller medications dispensed (relative risk, 0.7 2; 95% confidence interval, 0.69-0.74), they were equally likely to have th em 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 me dications should continue to be investigated as one cause of increased morb idity for low-income children with asthma.