Insurance-based differences in diagnostic resolution among women screened at a mobile mammography unit compared to a hospital-based site.

160 Background: Health insurance status impacts access to mammography services and downstream diagnostic follow-up. Mobile Mammography units (MMU) are a valuable tool for improving access for under- and uninsured women. This study aims to evaluate the impact of insurance status on diagnostic resolution in women receiving breast cancer screening in a MMU compared to an urban, hospital-based site. Methods: This retrospective study analyzed all screening mammography examinations with BI-RADS 0 assessments performed during two-week periods in 2022 and 2023 at a MMU and our hospital-based sites. All patients screened at the MMU received diagnostic follow-up at the hospital-based sites included in the study. Sociodemographic variables were obtained. The primary endpoint was time to diagnostic resolution, defined as time from abnormal screening mammogram to completion of diagnostic mammogram or biopsy, if indicated. Statistical analyses performed: chi-square, analysis of variance (ANOVA), and Kruskall-Wallis tests. Cox regression analysis was utilized to measure the effects between type of insurance and diagnostic resolution. Results: Compared to the hospital-based cohort (n = 236), more MMU patients (n = 97) were uninsured (71% vs. 2.1%, p < 0.001) and less had private insurance (15% vs. 60%, p < 0.001). The MMU cohort had longer time to diagnostic resolution (median 29 days, IQR 16-52) versus the hospital-screened cohort (median 14 days, IQR 7-29; p < 0.001). Uninsured women had longer median time to diagnostic resolution than women with private insurance (30 vs. 14 days, p < 0.001, Table 1) in both cohorts. Patients with no insurance had a lower rate of diagnostic resolution compared to patients with private insurance (HR 0.43, 95%CI [0.26, 0.71], p < 0.001). Conclusions: Women screened in a MMU were less likely to have health insurance and more likely to experience delayed and incomplete diagnostic work-up. Furthermore, insurance status impacts diagnostic resolution irrespective of site of care. This study highlights the importance of insurance status on timely and complete diagnostic resolution in all patients receiving screening mammography, regardless of screening site, and the need for robust navigation services in patients screened at a MMU. Median days to diagnostic resolution based on type of insurance. Overall Mobile Facility p-value N = 333 N = 97 N = 236 Median Days to Diagnostic Resolution (IQR) Medicaid (N = 42) 24 (36.5) 63 (61.8) 14.5 (23.3) < 0.001 Medicare (N = 60) 18 (22.8) 16 (7.5) 18 (25) 0.43 Private (N = 157) 14 (19.5) 19 (27.5) 13 (15.5) 0.02 Uninsured (N = 74) 30 (35.5) 30 (60.3) 22 (60.3) 0.49 Overall 17 (8,34) 14 (7,29) 29 (16,52) <0.001 Type of Insurance by Site (n, %) < 0.001 Medicaid (N = 42) 42 (13%) 10 (10%) 32 (14%) Medicare (N = 60) 60 (18%) 3 (3%) 57 (24%) Private (N = 157) 157 (47%) 15 (16%) 142 (60%) Uninsured (N = 74) 74 (22%) 69 (71%) 5 (2%)