Abandoning oral oncolytic prescriptions at the pharmacy: Patient and health plan factors influencing adherence.

6036 Background: Oral oncolytic agents are an increasingly important component of cancer therapy. Adherence with therapy begins with filling the prescription in a timely manner. Little is known of the factors associated with abandonment of oral oncolytics at the initial or subsequent prescription. METHODS This cross-sectional study analyzed a nationally representative pharmacy claims database and identified 10,508 Medicare and commercial patients initiating oral oncolytic therapy between 2007 and 2009. We calculated the rate of abandonment of the initial claim, where abandonment was defined as the reversal of an adjudicated pharmacy claim without a subsequent paid claim for any oncolytic (oral or IV) within the subsequent 90 days. The likelihood of abandonment was assessed using bivariate and multivariate logistic regression analyses including patent demographic factors, plan type, drug type, cost-sharing and number of other prescriptions. RESULTS The abandonment rate of newly initiated oral oncolytic agents was 10.0%. Unadjusted bivariate analyses found that high cost-sharing, larger prescription burden, lower income, and Medicare coverage were associated with a higher abandonment rate (p<0.01). Our logistic regression model found that as both cost-sharing and concurrent prescription use rose, there was a significantly higher likelihood of abandonment. Claims with cost-sharing over $500 were 4 times more likely to be abandoned than claims with cost-sharing of $100 or less (OR=4.46, p<0.001). Medicare patients were more likely to have cost-sharing over $500 than patients with commercial plans (p<0.001). Patients with 5 or more prescriptions in the previous month had 50% higher likelihood to abandon than patients with no prescription burden (OR=1.50, p<0.001). CONCLUSIONS Abandonment of newly prescribed oral oncolytic therapy is not uncommon, and the likelihood increases for patients enrolled in plans with pharmacy benefit designs that require high cost sharing. Higher prescription burden was also associated with a larger abandonment rate. These factors should be taken into account when considering likely adherence to cancer therapy.