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Background: In our previous study investigating mediators of the Black vs. White disparity in breast cancer survival for women in Florida, the two most important factors explaining the disparity were advanced disease stage at diagnosis and nonreceipt of surgery. Model assumptions of the multiple mediation approach used in that study prohibited examination causally prior (proximal) mediators. The purpose of this study was to: 1) quantify the excess risk of advanced disease stage at diagnosis and nonreceipt of surgery for Black vs. White women, and 2) use multiple mediation analysis to investigate the degree to which insurance status and high neighborhood poverty explain the racial disparity in these two outcomes. Methods: The study population was comprised of women in Florida diagnosed with breast cancer between 2004 and 2015 and who were reported to the Florida Cancer Data System. The potential mediators consisted of insurance status (Medicaid/Uninsured: yes/no) and census tract poverty level (High poverty [≥ 20% of households in poverty]: yes/no). The two outcomes of interest were advanced stage of disease at diagnosis (stages III/IV) and nonreceipt of surgery. The log-binomial model was used to obtain risk ratios (RR) with 95% confidence interval (CI) for the association of race with these two outcomes, adjusted for age. The multiple mediation approach of Yu et. al. was used to obtain log odds ratios (OR) to quantify direct effects, indirect effects, and the relative % of the total effect mediated. Results: There were 101,872 women available for analysis. African American women were 55% more likely to be diagnosed with advanced disease stage (RR = 1.55: 95% CI, 1.50-1.60) and 97% more likely more likely to not receive surgery (RR = 1.97: 95% CI, 1.90-2.04). The results of the multiple mediation analysis revealed that insurance status and high poverty explained 20.2% and 6.8%, respectively, of the racial disparity in advanced stage of disease at diagnosis. For the disparity in nonreceipt of surgery, insurance status explained 14.4% of the race effect and high poverty explained 5.2% of the race effect. Conclusions: Mediation analysis can provide insight into the mechanisms by which racial disparities in health outcomes occur. As was the case in this study, mediation analysis can also lead to new hypotheses concerning the most important factors causing disparities. To wit, contrary to our initial hypothesis, neither insurance status nor high poverty mediated the majority of the racial disparity in advanced disease stage at diagnosis or nonreceipt of surgery. Future research is required to obtain a better understanding of the barriers to screening mammography and receipt surgical treatment in Black women diagnosed with breast cancer. Citation Format: Robert B. Hines, Xiang Zhu, Eunkyung Lee, Bradley Eames, Karolina Chmielewska, Asal Johnson. Insurance status and neighborhood poverty as mediators of the racial disparity in advanced disease stage at diagnosis and nonreceipt of surgery for women with breast cancer in Florida [abstract]. In: Proceedings of the 15th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2022 Sep 16-19; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2022;31(1 Suppl):Abstract nr C003. |
