Long-term Adherence to Hormone Therapy in Medicaid-enrolled Women with Breast Cancer

Abstract

ObjectiveThis study assessed long-term adherence to hormone therapy in women with breast cancer enrolled in Medicaid. MethodsWe identified women diagnosed with nonmetastatic breast cancer (2000–2008) and prescribed tamoxifen or aromatase inhibitors (AIs) as hormone therapy within 1 year of diagnosis in the South Carolina Central Cancer Registry and South Carolina Medicaid linked data set. All the patients were followed-up for 1, 2, 3, or 4 years after initiation of hormone therapy. Adherence rate was measured as proportion of days covered (PDC) by tamoxifen or AIs in a given interval (1, 2, 3, or 4 years). Predictors of adherence to hormone therapy (PDC ≥80%) were identified using generalized linear models for repeated measures. ResultsThe population consisted of 612 eligible women who filled at least one prescription for AIs (n = 339, 55%) or tamoxifen (n = 273, 45%) within 1 year of diagnosis. The mean PDCs were 71% in the first year and 49% after 4 years. Only 25% of women receiving hormone therapy maintained a PDC of at least 80% after 4 years. ConclusionsLong-term use of hormone therapy remains low in the study population. Early interventions must be undertaken to improve adherence over the treatment period.