Cost Sharing and Asthma Medication Use in Children

Containing medication costs by shifting costs to patients is a strategy being increasingly utilized used by private health insurance plans. Studies have shown that when patients bear a greater proportion of medication costs, medication adherence rates decrease and visits to emergency departments (EDs) increase. There have been few studies to determine the effect of increased cost sharing among children with chronic illness.

Researchers recently designed a retrospective study to assess the association of medication cost sharing with medication adherence rates and use of hospital services among children with asthma. Study results were reported in the Journal of the American Medical Association [2012;307(12):1284-1291].

Utilizing data from pharmacy and medical claims from 1997 through 2008 for 37 geographically diverse US employers, the researchers identified children with asthma with a prescription for a long-acting asthma control medication. Based on ≥2 medical claims with an International Classification of Diseases, Ninth Revision diagnosis code for asthma, the researchers identified 60,737 eligible children. After applying inclusion and exclusion criteria, the final study cohort included 8834 children with newly diagnosed persistent asthma who were starting control therapy.

The researchers used variation in out-of-pocket costs for a fixed basket of asthma medications across the 37 employers and then estimated multivariate models of medication use, asthma-related hospitalization, and ED visits with respect to out-of-pocket costs and child and family characteristics. The primary outcome measures were asthma medication use, asthma-related hospitalizations, and ED visits during 1 year of follow-up.

Of the 8834 children included in the analysis, 2921 were <5 years of age (mean, 2.5 years) and 5913 were 5 to 18 years of age (mean, 9.7 years). The majority (59.9% of full sample) were male. The most commonly used asthma medications among both age groups were inhaled corticosteroids (86.3% of children <5 years of age and 75.4% of children 5-18 years of age) and leukotriene-receptor antagonists (70.3% of children <5 years of age and 62.5% of children 5-18 years of age).

Among children <5 years of age, the mean out-of-pocket costs of the standardized basket of asthma medications per year was $151; among those 5 to 18 years of age, the cost was $154. Among the younger study participants, filled asthma prescriptions covered a mean of 46.2% of days; among those 5 to 18 years of age, filled asthma prescriptions covered a mean of 40.9% of days.

Although child and family characteristics did not vary across plans with differing out-of-pocket asthma medication costs, unadjusted mean use of asthma control therapy decreased slightly, but not statistically significantly, with higher out-of-pocket medication costs. In the 5 to 18 years of age group, among children in the highest quartile of out-of-pocket costs, prescriptions covered 41.3% of days, compared with 42.2% of days for children in the lowest quartile.

Annual, unadjusted mean rates of asthma-related hospitalization were greater for children in the highest quartile of costs compared with those in the lowest quartile (2.7% vs 1.4%, respectively; P=.01).

An increase in out-of-pocket asthma medication costs from the 25th to the 75th percentile was associated with a small but significant reduction in the percentage of days covered by an asthma medication among children 5 to 18 years of age (41.7% vs 40.3%; P=.02); there was no change among children <5 years of age.

Among children 5 to 18 years of age, the adjusted rate of hospitalization associated with asthma was higher for those in the top quartile of out-of-pocket expenses compared with those in the lowest quartile (2.4 hospitalizations per 100 children vs 1.7 per 100 children, respectively; P=.004); there was no difference among those in the <5 years of age group. There was no difference in annual rates of ED use across out-of-pocket expenses quartiles for either age group.

In summary, the researchers said, “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.”