Background: The aim of this study was to investigate the risk of therapy discontinuation in breast cancer patients treated with tamoxifen with and without conversion to a rebate pharmaceutical (tamoxifen) and to analyze the negative consequences of rebate contracts on the compliance of breast cancer patients among gynecologist and general practitioner practices in Germany.
Methods: This retrospective analysis was performed using the IMS Disease Analyzer® database. Women with a diagnosis of breast cancer and first time prescription of tamoxifen in the time from January 2008 until December 2011 were selected. Main outcome measure was the incident the hormone treatment discontinuation rates within 3 years after index date. Treatment discontinuation of tamoxifen was defined as 90 days without this or alternative hormonal therapy (aromatase inhibitors) during that time.
Results: In total, 3,620 patients were included in the persistence analysis. 1,712 (47.3%) patients were converted to a rebate product. Within 3 years of follow-up, the discontinuation rates increased to 51.5% for switched patients and 46.3% for patients without switch (p < 0.01). Hazard ratios for 3-year risk of tamoxifen therapy discontinuation were adjusted for age, sex, gynecologist care, patient and physician's residency, baseline co-morbidities (osteoporosis, diabetes, depression and thrombosis, side effects). These analyses comprised a significantly increased risk for treatment discontinuation for patients who were switched to a rebate pharmaceutical compared to patients without conversion to a rebate pharmaceutical (HR: 1.27, CI: 1.05 - 1.53, p = 0.014).
Conclusions: This analysis underlines an association between the initiation of rebate contracts and a negative impact on the compliance of breast cancer patients on an adjuvant hormonal treatment The impact of rebate contracts on the health of patients and the health care costs should be evaluated in further therapeutic fields through additional research projects. *both authors contributed equally to the manuscript.