Rural-urban disparities in gallbladder cancer-related mortality in the United States (1999-2020).

Abstract

e22544 Background: Gallbladder cancer (GBC) is a rare but aggressive malignancy, accounting for over 50% of biliary tract cancers. The disparities in GBC-related mortality remain underexplored, particularly across rural and urban populations. This study examines trends in GBC-related mortality over two decades, focusing on differences by urbanization to identify at-risk populations and guide equitable care strategies. Methods: We obtained de-identified data from the Centers for Disease Control and Prevention Wide-Ranging Online Data for Epidemiologic Research (CDC WONDER) multiple causes of death database (years: 1999–2020) for the U.S. population with “malignant neoplasm of the gallbladder” (ICD-10 C23) listed as either “underlying” or “contributing” cause of death. Age-adjusted mortality rates (AAMRs) per million population were evaluated, and temporal trends in average annual percent change (AAPC) were assessed using Joinpoint regression. Pairwise comparisons examined differences in AAMR trends using average annual percent change difference (AAPCD) across large metropolitan, medium-to-small metropolitan, and rural areas based on the 2016 NCHS Urban-Rural Classification Scheme. Results: A total of 48,426 GBC-related deaths were recorded between 1999 and 2020. Overall, the AAMR significantly decreased during this period, from 8.1 to 5.8 per million individuals (AAPC: -1.39; 95% CI: -1.58 to -1.16; p < 0.01). The average AAMR was highest in large metropolitan areas (7.0), followed by rural areas (6.2) and small to medium metropolitan areas (6.0). Significant declines in AAMR were observed across all areas (table). However, the decline in AAMR was significantly greater in medium to small metropolitan areas compared to large metropolitan areas (AAPCD: 0.42; 95% CI: 0.10 to 0.74; p < 0.01). In contrast, no significant differences in AAMR trends were noted between large metropolitan and rural areas (AAPCD: 0.23; 95% CI: -0.29 to 0.74; p = 0.39) or between medium to small metropolitan and rural areas (AAPCD: -0.20; 95% CI: -0.72 to 0.32; p = 0.46). Conclusions: GBC-related mortality declined significantly from 1999 to 2020, with the steepest decrease observed in medium to small metropolitan areas. While large metropolitan areas had the highest average AAMR, the rate of decline in AAMR did not significantly differ between large metropolitan and rural areas or between medium to small metropolitan and rural areas. Efforts should focus on addressing persistent disparities and improving access to care in high-risk populations. The table below depicts trends in AAMRs per million using average AAPC from 1999 to 2020, stratified by urbanization status. Cohort Duration AAPC Lower CI Upper CI p-value Large Metropolitan 1999-2020 -1.27 -1.50 -1.03 <0.01 Medium to Small Metropolitan 1999-2020 -1.69 -1.93 -1.44 <0.01 Rural 1999-2020 -1.49 -1.99 -1.00 <0.01 Overall 1999-2020 -1.39 -1.58 -1.16 <0.01