Factors influencing patient adherence and persistence to hormonal therapy drugs in treatment of breast cancer

The purpose of this study was to investigate the relationship between patient out-of-pocket costs and adherence and persistence to hormonal therapy (HT) used in treatment of breast cancer. A retrospective analysis of medical and prescription drug claims for patients with breast cancer (N=6,504) was conducted to estimate the medication possession ratio; adherence; days of persistence; persistence; HT out-of-pocket costs, and total out-of-pocket costs, over 12 months after index HT and over the study period. The multivariate linear regression, logistic regression, and the Cox proportional hazard regression were employed to evaluate the association. The mean (SD) MPR over the 12 months and the study period was 85.6 (23.5) and 89.3 (16.1) percent, respectively. The MPR was positively related to HT out-of-pocket costs and not related to total out-of-pocket costs. Of the study sample, 75.1 percent of the patients were adherent (MPR≥80 percent) to HT over the 12 months period and 82.0 percent were adherent over the study period. The adherence to HT was positively related to HT out-of-pocket costs but not related to total out-of-pocket costs. The mean (SD) days of persistence over the 12 months and the study period were 313.3 (97.8) and 826.8 (583.7) days, respectively. HT out-of-pocket costs and total out-of-pocket costs were inversely related to risk of discontinuation over the 12 months period. The HT out-of-pocket costs and risk of discontinuation were inversely related over the study period. No relationship was observed between total-out-of-pocket costs and risk of discontinuation over the study period. A total of 68.2 percent of the patients were persistent to their therapy for the 12 months and 30.9 percent were persistent (gap of 60 days or less in continuous therapy) for the study period. A positive relationship was observed between HT out-of-pocket and total out-of-pocket costs and persistence during the 12 months period. The study period analyses showed positive relationship between HT out-of-pocket costs and persistence and no relationship between total out-of-pocket costs and persistence. The results show that patient HT adherence and persistence is poor; however, patient HT and total out-of-pocket costs do not have an adverse effect on adherence and persistence.