Investigating racial disparities in use of NK1 receptor antagonists to prevent chemotherapy-induced nausea and vomiting among women with breast cancer.

Chemotherapy-induced nausea and vomiting (CINV) is a major concern for cancer patients and, if uncontrolled, can seriously compromise quality of life (QOL) and other treatment outcomes. Because of the expense of antiemetic medications used to prevent CINV (particularly oral medications filled through Medicare Part D), disparities in their use may exist. We used 2006-2012 SEER-Medicare data to evaluate the use of neurokinin-1 receptor antagonists (NK1s), a potent class of antiemetics, among black and white women initiating highly emetogenic chemotherapy for the treatment of early-stage breast cancer. We used modified Poisson regression to assess the relationship between race and (1) any NK1 use, (2) oral NK1 (aprepitant) use, and (3) intravenous NK1 (fosaprepitant) use. We report adjusted risk ratios (aRR) and 95 % confidence intervals (CI). The study included 1130 women. We observed racial disparities in use of any NK1 (aRR: 0.68, 95 % CI 0.51-0.91) and in use of oral aprepitant specifically (aRR: 0.54, 95 % CI 0.35-0.83). We did not observe disparities in intravenous fosaprepitant use. After controlling for variables related to socioeconomic status, disparities in NK1 and aprepitant use were reduced but not eliminated. We found racial disparities in women's use of oral NK1s for the prevention of CINV. These disparities may be partly explained by racial differences in socioeconomic status, which may translate into differential ability to afford the medication.