Objective: To calculate the abandonment rate of oral oncolytic medications and identify factors that may affect likelihood of abandonment.
Study design: Cross-sectional cohort study using administrative claims data.
Methods: We analyzed a nationally representative pharmacy claims database and identified 10,508 patients with Medicare and commercial insurance for whom oral oncolytic therapy was initiated between 2007 and 2009. We calculated the abandonment rate for the initial claim, in which abandonment was defined as reversal of an adjudicated pharmacy claim without a subsequent paid claim for any oncolytic (oral or intravenous) within the ensuing 90 days. We assessed likelihood of abandonment using bivariate and multivariate logistic regression analyses including patient demographics, plan type, drug type, cost sharing, and concurrent prescription activity.
Results: The abandonment rate of newly initiated oral oncolytics was 10.0%. Unadjusted bivariate analyses found that high cost sharing, increased prescription activity, lower income, and Medicare coverage were associated with a higher abandonment rate (P <.05). In the logistic regression model, claims with cost sharing greater than $500 were 4 times more likely to be abandoned than claims with cost sharing of $100 or less (odds ratio [OR], 4.46; P <.001). Patients with 5 or more prescription claims processed within in the previous month had 50% higher likelihood of abandonment than patients with no other prescription activity (OR, 1.50; P <.001).
Conclusion: 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. Increased concurrent prescription activity was also associated with a higher abandonment rate. These factors should be taken into account when considering likely adherence to cancer therapy.