Association of out-of-pocket pharmacy costs with adherence to varenicline

摘要

Background: Varenicline, a nicotinic acetylcholine receptor partial agonist, is a pharmacotherapy indicated for smoking cessation treatment. To date, no research has examined the relationship between out-of-pocket (OOP) expense and varenicline adherence among Medicare beneficiaries. Objectives: To (a) characterize medication utilization patterns of varenicline among Medicare members newly initiated on varenicline and (b) examine the relationship between member OOP expense and varenicline medication adherence. METHODS: In this retrospective cohort study, pharmacy claims data were used to identify Medicare Advantage Prescription Drug Plan (MAPD) members newly initiated on varenicline. Demographic and clinical characteristics, varenicline medication utilization patterns, and pharmacy costs (total and varenicline-specific) were determined for members included in the study. Varenicline adherence was measured by calculating the proportion of days covered (PDC) over a period of 84 days (12 weeks) after initiation. Multiple regression analysis was used to examine the relationship between varenicline OOP cost and varenicline medication utilization, while controlling for sociodemographic characteristics, clinical factors, and nonvarenicline pharmacy costs. Results: A total of 15,452 MAPD members were included in the analysis. Mean (SD) subject age was 62.6 (10.0) years; 21.1% (n = 3,256) were dual eligible; and 33.0% (n = 5,106) received a low-income subsidy. Mean (SD) initial varenicline treatment episode duration was 50.8 (37.8) days, with a mean (SD) varenicline days' supply of 47.8 (32.6) obtained by members during the initial treatment episode. Mean (SD) PDC was 0.51 (0.24), and 14.9% (n = 2,302) of members were classified as adherent to treatment (PDC ≥ 0.80). Greater varenicline OOP expense was significantly associated with lower PDC (regression coefficient = -0.058, P < 0.001) and significantly associated with lower odds of receiving a refill for varenicline (odds ratio 0.594, 95% CI: 0.540-0.655, P < 0.001). Conclusions: Among Medicare beneficiaries newly initiated on varenicline, medication adherence was suboptimal, and greater OOP cost was associated with lower adherence and lower odds of refilling varenicline.