Introduction:Preemptive wait-listing of deceased donor kidney transplant (DDKT) candidates before maintenance dialysis increases the likelihood of transplantation and improves outcomes among transplant patients. Previous studies have identified substantial disparities in rates of preemptive listing, but a gap exists in examining geographic sources of disparities, particularly for sub-regional units. Identifying small area hot spots where delayed listing is particularly prevalent may more effectively inform both health policy and regionally appropriate interventions. Methods:We conducted a retrospective cohort study utilizing 2010-2020 Scientific Registry of Transplant Recipients (SRTR) data for all DDKT candidates to examine overall and race-stratified geospatial hot spots of post-dialysis wait-listing in U.S. zip code tabulation areas (ZCTA). Three geographic clustering methods were utilized to identify robust statistically significant hot spots of post-dialysis wait-listing.Results: Novel sub-regional hot spots were identified in the southeast, southwest, Appalachia, and California, with a majority existing in the southeast. Race-stratified results were more nuanced, but broadly reflected similar patterns. Comparing transplant candidates in hot spots to candidates in non-clusters indicated a strong association between residence in hot spots and high area deprivation (OR: 6.76, 95%CI: 6.52-7.02), indicating that improving access healthcare in these areas may be particularly beneficial. Conclusion:Our study identified overall and race-stratified hot spots with low rates of preemptive wait list placement in the U.S., which may be useful for prospective healthcare policy and interventions via targeting of these narrowly defined geographical areas.

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The U.S. Hispanic population has significantly lower colorectal cancer (CRC) screening rates than any other racial/ethnic group, resulting in unchanged incidence and mortality rates over recent decades. Recent studies have identified geographic variation in Hispanic CRC screening rates, but little is known about patterns among Hispanic subgroups. Here, we examine statistical and geographic relationships between broadly defined racial groups, Hispanic subgroups, and nationwide CRC screening rates. USPSTF guideline-adherent CRC screening rates for census tracts were obtained from 2018 CDC Places. Tract race/ethnicity %s, including non-Hispanic White (NHW), non-Hispanic Black (NHB), Asian, and Hispanic subgroups (Mexican, Cuban, Puerto Rican (PR), Dominican, Central/South American (CSAm), and other Hispanic), female %, and area deprivation index (ADI) were obtained from 2015-2019 American Community Survey 5-year estimates. Race/ethnicity %s were transformed using additive log ratios to account for the compositional nature of racial categories. A linear model and geographically weighted regression (GWR) were fit with CRC screening rate as the outcome. The mean CRC screening rate for 72,117 U.S. census tracts (99% of tracts) was 63.7% (SD=7.0). Linear modeling (R2=0.68) showed significant positive linear associations between CRC screening and female % (p&lt0.001), NHW % (p&lt0.001), NHB % (p&lt0.001), and Asian % (p=0.002), and significant negative associations between screening and ADI (p&lt0.001) and all Hispanic subgroups (p&lt0.001). Mexican, Cuban, PR, Dominican, and CSAm subgroups had significant screening rate drops of -1.48%, -0.26%, -0.15%, -0.30%, and -0.52%, respectively, per 1 unit increase in subgroup %. ADI had strong effects on all screening-race associations, with a flip in directionality for NHB% (negative to positive) and weakening of slopes for all other racial categories after adding ADI in the final adjusted model. GWR results (R2=0.94) displayed spatial heterogeneity in local coefficients of all predictor variables, with distinct regional patterns in relationships between screening and ADI (strongly negative local coefficients in OH and OK), Mexican % (strongly negative in TX, AZ, NV, and CA), and NHB % (strongly negative in FL, GA, MS and WI; positive in SC and NC). This work suggests Mexican, CSAm, and Dominican subpopulations may be driving the low CRC screening rates among Hispanics overall. Local variability suggested the importance of where subpopulations live in determining guideline-concordant screening. ADI strongly altered screening-race relationships, with directionality changing for NHB %, further displaying the importance of area deprivation in CRC screening. Future work should explore micro-level drivers of spatial heterogeneity in screening rates across both broadly defined racial groups and Hispanic subgroups in the U.S. Citation Format: Robert Blake Buchalter, Johnie Rose, Mariana C. Stern, Jane C. Figueiredo, Stephanie L. Schmit. Geospatial heterogeneity in colorectal cancer screening among Hispanic subgroups. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4181.