Health care utilization and cost among children with asthma who were enrolled in a health maintenance organization.

OBJECTIVE To measure the impact of asthma on the use and cost of health care by children in a managed care organization. DESIGN Population-based historical cohort study. SETTING A medium-sized staff model health maintenance organization in western Washington state. SUBJECTS All 71 818 children, between age 1 to 17 years, who were enrolled and used services during 1992. OUTCOME MEASURES Children were identified with one or more asthma diagnoses during 1992 using automated encounter data. Nonurgent outpatient visits, pharmacy fills, urgent care visits, and hospital days, as well as associated costs were measured. All services were categorized as asthma care or nonasthma care. Multivariate regression analysis was used to compute marginal cost for asthma (difference in total cost between children with asthma and other children using services, adjusted for covariates). RESULTS Treated prevalence of asthma was 4.9%. Children with asthma incurred 88% more costs ($1060.32 vs $563. 81/yr), filled 2.77 times as many prescriptions (11.59 vs 4.19/yr), made 65% more nonurgent outpatient visits (5.75 vs 3.48/yr), and had twice as many inpatient days (.23 vs .11/yr) compared with the general population of children using services. Asthma care represented 37% of all health care received by children with asthma, while the remaining 63% were for nonasthma services. Almost two-thirds of asthma-related costs were attributable to nonurgent outpatient care and prescriptions; only one third was attributable to urgent care and hospitalizations. Controlling for age, sex, and comorbidities, the marginal cost of asthma was $615.17/yr (95% confidence interval $502.73, $727.61), which includes asthma as well as nonasthma services. This marginal cost represents 58% of all health care costs for children with asthma. CONCLUSIONS Children with asthma use significantly more health services (and incur significantly more costs) than other children using services, attributable largely to asthma care. The majority of all health care costs for children with asthma were for nonasthma services. Urgent care visits and hospitalizations are less important components of asthma costs in this managed care organization than has been found in other national studies.