Association Between Prescription Co-payment Amount and Compliance with Adjuvant Hormonal Therapy in Women with Early-stage Breast Cancer

Purpose: Noncompliance with adjuvant hormonal therapy among women with breast cancer is common. Little is known about the impact of financial factors, such as co-payments, on noncompliance.

Patients And Methods: We conducted a retrospective cohort study by using the pharmacy and medical claims database at Medco Health Solutions. Women older than age 50 years who were taking aromatase inhibitors (AIs) for resected breast cancer with two or more mail-order prescriptions, from January 1, 2007, to December 31, 2008, were identified. Patients who were eligible for Medicare were analyzed separately. Nonpersistence was defined as a prescription supply gap of more than 45 days without subsequent refill. Nonadherence was defined as a medication possession ratio less than 80% of eligible days.

Results: Of 8110 women younger than age 65 years, 1721 (21.1%) were nonpersistent and 863 (10.6%) were nonadherent. Among 14,050 women age 65 years or older, 3476 (24.7%) were nonpersistent and 1248 (8.9%) were nonadherent. In a multivariate analysis, nonpersistence (ever/never) in both age groups was associated with older age, having a non-oncologist write the prescription, and having a higher number of other prescriptions. Compared with a co-payment of less than $30, a co-payment of $30 to $89.99 for a 90-day prescription was associated with less persistence in women age 65 years or older (odds ratio [OR], 0.69; 95% CI, 0.62 to 0.75) but not among women younger than age 65, although a co-payment of more than $90 was associated with less persistence both in women younger than age 65 (OR, 0.82; 95% CI, 0.72 to 0.94) and those age 65 years or older (OR, 0.72; 95% CI, 0.65 to 0.80). Similar results were seen with nonadherence.

Conclusion: We found that higher prescription co-payments were associated with both nonpersistence and nonadherence to AIs. This relationship was stronger in older women. Because noncompliance is associated with worse outcomes, future policy efforts should be directed toward interventions that would help patients with financial difficulties obtain life-saving medications.