Association Between Pharmacy Benefit Restrictions and Disease-Modifying Therapy Use in the Medicare Part D Program

Abstract Objective: To determine the association between Medicare Part D Plan disease-modifying therapy (DMT) restrictiveness and adherence and outcomes among people with multiple sclerosis (MS) Methods: We used Medicare claims data from 2010 to 2014 to identify individuals with a full year enrollment (Part A, B, D), an MS diagnosis, and one or more self-administered DMT prescription. Plans were considered restrictive if all available DMTs required a prior authorization or step therapy restriction; otherwise they were considered permissive. We compared DMT adherence, defined as a medication possession ratio (MPR) >=80%, MS-related emergency department (ED) or inpatient admissions, and outpatient visits by Part D plan restrictiveness. We used multivariate regression models to control for patient demographics and comorbidities. Results: There were 37,713 Medicare beneficiaries with MS who were enrolled in either restrictive (n=29,901) or permissive (n=7812) Part D plans during the study period. Patients enrolled in restrictive plans were older (60 versus 58 years; p Conclusions: Medicare beneficiaries with MS enrolled in restrictive Part D plans were less adherent to their DMT and had higher rates of MS-related outpatient visits.