Cost shifting of asthma meds to patients had little effect on adherence, outcomes

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Health insurance plans are shifting an increasing portion of costs for prescription medications onto patients. A recent study in JAMA concluded that such cost shifting decreased asthma medication use and increased hospitalization rates in U.S. children. But the effect, if real, was small.

What They Did

Pinar Karaca-Mandic et al looked back at pharmacy and insurance claims for 8,834 children with asthma, 1997-2007. They calculated the days of asthma medication use by the total doses contained in the prescriptions filled for each child. They could also tell when the child went to the emergency department or was hospitalized. They had access to the co-pays and tiers of each insurance plan's pharmacy benefit, so they could calculate the cost borne by each child's family.

What They Found

Families of children in the 75th percentile for cost-sharing expense paid $190 / year out-of-pocket, compared to $100 / year for those in the 25th percentile. Authors concluded that "greater cost sharing for asthma medications was associated with a slight reduction in medication use and higher rates of asthma hospitalization" among children aged 5-18. But how reduced, and how increased?

• The highest quartile (75th percentile, $190/year) for cost filled prescriptions covering 40.3% of the days.

• The lowest quartile (25th percentile, $100/year) filled prescriptions covering 41.7% of the days.

• So on any given day, if 100 kids were playing, perhaps 1 or 2 did not take a medicine that day because of increased cost sharing.

• There were 0.7 more hospitalizations per 100 children per year (2.4 in the highest-cost, 1.7 in the lowest-cost quartiles).

• Yet there were no differences in the rate of emergency department visits across any of the quartiles. (Wouldn't this be a more sensitive measure of asthma control, and vary more between groups, if cost shifting had an important effect?)

Children infrequently use their prescribed asthma medication, not because they're "non-adherent," but because they're kids. Guidelines allow for seasonal or as-needed use, acknowledging the realities that it's nearly impossible to get a kid to take an inhaler every day and that some kids only have symptoms part of the year.

Pinar Karaca-Mandic et al. Out-of-Pocket Medication Costs and Use of Medications and Health Care Services Among Children With Asthma. JAMA 2012;307:1284-1291.