The Association Between Out-of-Pocket Costs and Adherence to Adjuvant Endocrine Therapy Among Newly Diagnosed Breast Cancer Patients.

Abstract

To determine how out-of-pocket costs for adjuvant endocrine therapy (AET) medication affects adherence among newly diagnosed breast cancer survivors with private health insurance who initiate therapy. We examined medical and pharmacy claims for the 1-year period after initiating AET using the Truven Health Analytics MarketScan database. Adherence was defined as ≥80% proportion of days covered. Mean out-of-pocket costs for AET fill were measured as the sum of copayments, coinsurance, and deductibles and adjusted to 30-day amounts. Using a multivariable logistic regression model we calculated adjusted risk ratios controlling for age, comorbidities, type of surgery, use of chemotherapy and/or radiation therapy, average out-of-pocket costs for other services, and pharmacy use characteristics. Of the 6863 women 64 years and younger who were diagnosed with breast cancer and initiated AET, 73.9% were adherent (proportion of days covered≥80%). A total of 19% of patients had <$5 monthly out-of-pocket costs for AET, 30% had $5 to $9.99, 17% had $10 to $14.99, 10% had $15 to $19.99, and 25% had $20 or greater. Patients with out-of-pocket costs for AET between $10 and $14.99, $15 and $19.99, and >$20 were 6% to 8% less likely to be adherent compared with patients paying <$5.00, after controlling for covariates (P<0.05). Out-of-pocket costs for inpatient, outpatient, and other pharmacy services were not associated with adherence. A substantial proportion of privately insured patients are nonadherent to AET and out-of-pocket costs for AET medication are significantly associated with a greater likelihood of nonadherence.