Abstract
PURPOSE: Nonadherence to adjuvant hormonal therapy is common and is associated with increased prescription copayment amount and black race. Studies suggest that household wealth may partly explain racial disparities. We investigated the impact of net worth on disparities in adherence and discontinuation. PATIENTS AND METHODS: We used the OptumInsight insurance claims database to identify women older than age 50 years diagnosed with early breast cancer, from January 1, 2007, to December 31, 2011, who were using hormonal therapy. Nonadherence was defined as a medication possession ratio of ≤ 80% of eligible days over a 2-year period. We evaluated the association of demographic and clinical characteristics, annual household income, household net worth (< $250,000, $250,000 to $750,000, or > $750,000), insurance type, and copayments (< $10, $10 to $20, or > $20) with adherence to hormonal therapy. Logistic regression analyses were conducted by sequentially adding sociodemographic and financial variables to race. RESULTS: We identified 10,302 patients; 2,473 (24%) were nonadherent. In the unadjusted analyses, adherence was negatively associated with black race (odds ratio [OR], 0.76; P < .001), advanced age, comorbidity, and Medicare insurance. Adherence was positively associated with medium (OR, 1.33; P < .001) and high (OR, 1.66; P < .001) compared with low net worth. The negative association of black race with adherence (OR, 0.76) was reduced by adding net worth to the model (OR, 0.84; P < .05). Correcting for other variables had a minimal impact on the association between race and adherence (OR, 0.87; P = .08). The interaction between net worth and race was significant (P < .01). CONCLUSION: We found that net worth partially explains racial disparities in hormonal therapy adherence. These results suggest that economic factors may contribute to disparities in the quality of care.