Evaluation of Patient Migration Patterns and Related Health Care Costs Within a National Medicare Advantage Prescription Drug Plan After Implementation of an Oxycodone HCl Extended-Release Access Restriction.

Abstract

Health plans use formulary restrictions (e.g., prior authorization, step therapy, tier change, nonformulary status) in an effort to control cost and promote quality, safety, and appropriate prescription utilization. Some Medicare payers perceive that the inclusion of certain agents, such as branded oxycodone HCl extended-release tablets (OERs), on their formularies is associated with attracting high-cost members to the plan. To evaluate disenrollment rates, patient migration, and subsequent health care costs among OER users who disenrolled from a national Medicare Advantage Prescription Drug plan (study-MAPD) in the plan year following OER nonformulary restriction. A retrospective, longitudinal cohort study using IMS pharmacy and medical claims data between July 1, 2011, and December 31, 2014, was conducted. In the study-MAPD, adults aged ≥ 18 years who were chronic OER users with ≥ 2 OER claims 6 months before the nonformulary restriction date on January 1, 2013 (index date) and with continuous activity in pharmacy and medical claims for 6 months pre- and post-index were included in the study. Comparison years of 2012 and 2014 prerestriction/postrestriction were selected. All groups were followed for 6 months postindex. Year-to-year disenrollment rates of OER patients and the overall plan, as well as patient characteristics and costs of those who disenrolled from and those who remained with the plan, were measured. Costs were compared using a difference-in-differences approach. This study identified 2,935 eligible OER users from the study-MAPD population after imposing nonformulary restrictions on OERs on January 1, 2013. Mean age was 62.1 years, and 59.8% were female. The mean Charlson Comorbidity Index score was 1.83 for those 1,001 patients with medical claims data. For comparison years 2012 (prerestriction) and 2014 (postrestriction), 2,248 and 2,222 OER patients were identified, respectively. Patient characteristics were similar across patient cohorts in all 3 study years. Disenrollment rates for OER users (12.9%, 5.5%, and 14.3% for years 2012, 2013, and 2014, respectively) were lower or similar to those of the overall plan (18.3%, 7.6%, and 14.1%, respectively, for the same 3 years). Approximately 40% of OER users who disenrolled from the study-MAPD migrated to plans also imposing a nonformulary restriction on OERs, while about 25% moved to plans with less restrictive OER coverage. The majority (59.9%) of patients continued OER use irrespective of their disenrollment from the study-MAPD in 2013. Although a nonsignificant decrease ($117; P = 0.340) in per patient per month (PPPM) cost was observed among OER patients postrestriction (from 2012 to 2013), the difference-in-difference analysis indicated a net postrestriction increase of $124 (P = 0.461) in PPPM for OER patients. This study found little evidence to support any consistent directional effect on patient enrollment behavior as a result of an OER non-formulary restriction. Implementation of an OER nonformulary restriction did not lead to higher OER patient disenrollment or lower patient costs in the study-MAPD. Funding for this study was provided by Purdue Pharma. De, Chen, and Wade are employees of QuintilesIMS, a for-profit company that was contracted by Purdue Pharma to undertake this research. Sweet was a paid consultant for Purdue Pharma at the time of this study. Study concept and design were contributed by Chen, Wade, and De. Chen, De, and Wade collected the data, which were interpreted by all the authors. The manuscript was written by Chen and De, along with Sweet and Wade, and revised by all the authors.