Co-pay Eliminating Associated with Increased Medication Utilization and Compliance in Asthma medications

BACKGROUND: Value-Based Insurance Design plans offer reduced co-pays as a way to increase compliance with high value medications used to treat chronic illness. It remains unclear however if decreasing co-pays for these types of medications is related to improved medication utilization and adherence.

OBJECTIVE: The current study evaluates the impact of eliminating co-pays for drugs used for the treatment of asthma on measures of medication adherence and utilization.

METHODS: A pre-post study design was used to compare changes in outcomes during a 12-month baseline period (2006) and post-co-pay elimination period (2007). The study group consisted of patients of an employer sponsored pharmacy benefit plan that eliminated employee out of pocket costs for asthma medications (N=673). The control group consisted of patients selected from 10 employers sponsored plans that maintained consistent employee cost-share during the study period (N=2072). Patients 5 – 56 years of age were included in the analysis. Adherence measures included: Medication Possession Ratio (MPR), and proportion of rescue medication prescriptions to total asthma medication prescriptions. Asthma medication utilization was measured by the percent of patients that filled at least one controller medication prescription and the percent of patients that filled more than 6 controller medication prescriptions. Difference-in-difference analyses were used to estimate the effect of co-pay elimination. Logistic and generalized linear models were adjusted for age, gender, chronic disease score, and oral steroid use.

RESULTS: Overall MPR, demographic characteristics and plan characteristics for the study and control groups were similar at baseline. Post-co-pay elimination, the overall MPR increased from 0.46 to 0.48 for the study group and decreased from 0.43 to 0.41 for the control group. The difference in MPR between baseline and follow up period for the study group resulted in 4.7% greater compliance in the reduced co-pay study group (p = 0.001). The proportion of rescue prescription decreased 1.8% in the study group compared to 0.7% in the control group (p=0.432). The percent of patients that filled at least one controller medication prescription increased 2.2% in the study group and decreased 0.4% in the control group (p=0.252). The percent of patients that filled >6 controller prescriptions increased 5.7% in the study group and deceased 1.0% in the control group (p=0.04).

CONCLUSIONS: Eliminating employee out of pocket costs for asthma medications resulted in directional and statistically significant increases in medication compliance and greater controller medication utilization.