Effect of concurrent prescription antiarthralgia pharmacotherapy on persistence to aromatase inhibitors in treatment-naive postmenopausal females.

BACKGROUND: Aromatase inhibitors function by suppressing estrogen biosynthesis in peripheral tissues. The resulting estrogen deprivation is considered the underlying cause for aromatase inhibitor-induced arthralgia, which affects patients' quality of life and may affect their persistence to aromatase inhibitor therapy. The effect of concurrent treatment with aromatase inhibitors and prescription antiarthralgia pharmacotherapy on improving persistence to aromatase inhibitor therapy is unknown.
OBJECTIVE: To evaluate the effect of concurrent prescription antiarthralgia pharmacotherapy on persistence to aromatase inhibitor therapy in treatment-naïve postmenopausal women.
METHODS: This retrospective cohort pharmacy claims study examined the drug utilization pattern between July 2008 and October 2009 of postmenopausal females, naïve to aromatase inhibitor therapy, with 18 months of continuous prescription benefit eligibility. Patients were divided into 2 groups: group A (control) included patients who did not have a claim for a prescription antiarthralgia medication in a 1-year follow-up period, while group B (active) included patients with prescription antiarthralgia medications started within the 1-year follow-up period after starting treatment with an aromatase inhibitor. Persistence to aromatase inhibitor therapy was compared between the 2 groups.
RESULTS: The study population comprised 29,967 patients: 24,804 (82.8%) in group A, and 5163 (17.2%) in group B. Aromatase inhibitor discontinuation rates within the first year of therapy were not statistically significantly different between groups: 40.9% in group A (10,145/24,804) and 34.5% in group B (1781/5163) (HR 1.127; 95% CI 0.900-1.411; p = 0.297). Persistence for the 2 groups did not differ statistically significantly for any of the 3 aromatase inhibitors measured separately.
CONCLUSIONS: Postmenopausal females treatment-naïve to aromatase inhibitor therapy who also received treatment with a prescription antiarthralgia medication did not have significantly higher persistence with aromatase inhibitor therapy. Further research should focus on other possible causes of poor persistence in patients using aromatase inhibitor therapy.