Hormonal Therapy Drug Switching, Out-of-Pocket Costs, and Adherence among Older Women with Breast Cancer
Menée à partir des données de la base Medicare et des registres américains des cancers portant sur 20 677 patientes âgées de plus de 65 ans et atteintes d'un cancer du sein HR+, cette étude analyse l'association entre une utilisation d'inhibiteurs de l'aromatase, leur remplacement par des médicaments génériques, une réduction des coûts restant à charge et une augmentation de l'adhésion au traitement
Background : Adherence to aromatase inhibitors (AIs) and tamoxifen has significant survival benefits for postmenopausal women diagnosed with hormone receptor-positive (HR+) breast cancer. Reduced out-of-pocket (OOP) costs and treatment-related side effects could increase therapy adherence. Given that individuals’ side effect profiles could differ across AIs, generic AI entry could facilitate switching between AIs to manage side effects and improve adherence. Methods : From SEER-Medicare, we selected women first diagnosed with HR+ breast cancer at age 65+ and initiated an AI within one year of diagnosis between 1/1/2007–5/31/2008 or 6/1/2011–12/31/2012 and followed them for up to two years (N = 20,677). We estimated changes in probabilities of adherence with and without switching for Part D enrollees with and without the low-income subsidy (LIS vs. non-LIS) before and after generic entry, using linear probability models. Tests of statistical significance are two-sided. Results : After generic entry reduced OOP costs of AIs (larger reduction for non-LIS), percent of women who ever switched from one AI to another AI increased from 8.8% to 14.6% for non-LIS and from 7.3% to 12.5% for LIS. Adherence without switching increased by 8.0 percentage points (pp) for non-LIS (P < 0.001) but decreased by 4.9 pp (P < 0.001) for LIS. Adherence with switching increased for both non-LIS (6.4 pp, P < 0.001) and LIS (4.4 pp, P < 0.001). Conclusions : Increased switching after generic entry contributed to increased adherence, suggesting switching allowed better management of treatment-related side effects. Subsidized women also experienced increased adherence with switching after generic entry suggesting that patients and physicians might not understand Part D benefit design when making decisions.