Out-of-pocket medication costs and use of medications and health care services among children with asthma

Context: Health plans have implemented policies to restrain prescription medication spending by shifting costs toward patients. It is unknown how these policies have affected children with chronic illness. Objective: To analyze the association of medication cost sharing with medication and hospital services utilization among children with asthma, the most prevalent chronic disease of childhood. Design, Setting, and Patients: Retrospective study of insurance claims for 8834 US children with asthma who initiated asthma control therapy between 1997 and 2007. Using variation in out-of-pocket costs for a fixed "basket" of asthma medications across 37 employers, we estimated multivariate models of asthma medication use, asthmarelated hospitalization, and emergency department (ED) visits with respect to out-of-pocket costs and child and family characteristics. Main Outcome Measures: Asthma medication use, asthma-related hospitalizations, and ED visits during 1-year follow-up. Results: The mean annual out-of-pocket asthma medication cost was $154 (95% CI, $152-$156) among children aged 5 to 18 years and $151 (95% CI, $148-$153) among those younger than 5 years. Among 5913 children aged 5 to 18 years, filled asthma prescriptions covered a mean of 40.9% of days (95% CI, 40.2%-41.5%). During 1-year follow-up, 121 children (2.1%) had an asthma-related hospitalization and 220 (3.7%) had an ED visit. Among 2921 children younger than 5 years, mean medication use was 46.2% of days (95% CI, 45.2%-47.1%); 136 children (4.7%) had an asthma-related hospitalization and 231 (7.9%) had an ED visit. An increase in out-of-pocket medication costs from the 25th to the 75th percentile was associated with a reduction in adjusted medication use among children aged 5 to 18 years (41.7% [95% CI, 40.7%-42.7%] vs 40.3% [95% CI, 39.4%-41.3%] of days; P=.02) but no change among younger children. Adjusted rates of asthma-related hospitalization were higher for children aged 5 to 18 years in the top quartile of out-of-pocket costs (2.4 [95% CI, 1.9-2.8] hospitalizations per 100 children vs 1.7 [95% CI, 1.3-2.1] per 100 in bottom quartile; P=.004) but not for younger children. Annual adjusted rates of ED use did not vary across out-of-pocket quartiles for either age group. Conclusion: Greater cost sharing for asthma medications was associated with a slight reduction in medication use and higher rates of asthma hospitalization among children aged 5 years or older.