Abstract SS1-10: Impact of Medicaid expansion on racial disparities in time to adjuvant chemotherapy administration among breast cancer (BC) patients
Authors: Chavez-MacGregor Mariana , Lei Xiudong , Zhao Hui , Shih Tina , Giordano Sharon H 
Published: February 2021

BACKGROUND: Delays in adjuvant chemotherapy initiation have a detrimental effect in outcomes and are more frequently seen among racial/ethnic minorities, uninsured patients and those with low socioeconomic status. A provision in the Affordable Care Act called for expansion of Medicaid eligibility in order to cover more low-income Americans. In this study we evaluate the impact of Medicaid expansion on racial disparities in time to adjuvant chemotherapy administration in a large cohort of BC patients.METHODS: Women (aged 40-64) diagnosed with primary invasive BC (stage I-III) between 01/01/2007 and 12/31/2016 were identified in the National Cancer Database. All patients underwent surgery as initial treatment modality and received adjuvant chemotherapy within 6 months of surgery. Chemotherapy delay was defined as &gt;60 days from surgery to the first dose of chemotherapy. The cohort was limited to those residing in states that underwent Medicaid expansion in 2014 (KY, NV, CO, OR, NM, WV, AR, RI, AZ, MD, MA, ND, OH, IA, IL, VT, HI, NY, DE). For comparison purposes, 2007-2013 was considered the pre-expansion period and 2014-2016 the post-expansion period. We calculated difference-in-difference (DID) estimates using multivariable linear regression models. Results are presented as adjusted differences (in % points) between race/ethnicity groups in the pre and post-expansion periods, and as adjusted DID with 95% CI. A negative DID estimate indicates that Medicaid expansion reduces the racial/ethnic disparity in chemotherapy administration delay. The parallel trend assumption was tested. Variables in the final model included age, comorbidities, BC subtype, insurance status, distance to treatment facility, region, education, household income, facility type and facility case volume. RESULTS: 105,385 patients were included (median age 53), of them 75,663 (71.8%) were diagnosed in the pre- and 29,722 (28.2%) in the post-expansion period. 77.5% of the patients were White, 11.7% Black and 4.9% Hispanic. The proportion of patients experiencing chemotherapy initiation delays was greater among Blacks and Hispanics in both study periods compared to Whites. The proportion of chemotherapy delays decreased for all races between the pre and the post-expansion period. We observed a statistically significant decrease in the chemotherapy initiation racial disparity. The adjusted DID was -2% (95%CI -3.8 to -0.3, P=0.02) between Whites and Blacks was and -3% (95%CI -5.5 to -0.5, P=0.02) between Whites and Hispanics. In a subgroup analysis among 10,777 Medicaid patients the parallel trend assumption was not valid, therefore we estimated the DID between Whites and Blacks using a propensity-score based weight sample, identifying a reduction in the racial disparity of even greater magnitude (DID -9.1% [-14.4 to -3.8, P&lt;0.001]).

CONCLUSIONS: We demonstrate that Medicaid expansion reduced racial disparities by decreasing the proportion of Blacks and Hispanics experiencing delays in adjuvant chemotherapy initiation and decreasing the gap that exists when compared to Whites. These important results highlight the positive impact of policies aimed at improving equity and increasing access to health care.

Pre-ExpansionPost-ExpansionRaceNAdjusted Rate of Delayed Chemo &gt; 60 daysAdjusted Difference Between White Race (% points)NAdjusted Rate of Delayed Chemo &gt; 60 daysAdjusted Difference Between White Race, (%points)Adjusted DID (95% CI), Percentage PointsPWhite5930527.202232524.20RefRefBlack856036.18.9372031.16.9-2.0 (-3.8 to -0.3)0.02Hispanic343232.35.1170426.32.1-3.0 (-5.5 to -0.5)0.02

Citation Format: Mariana Chavez-MacGregor, Xiudong Lei, Hui Zhao, Tina Shih, Sharon H Giordano. Impact of Medicaid expansion on racial disparities in time to adjuvant chemotherapy administration among breast cancer (BC) patients [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr SS1-10.