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, asthma-related 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.