Ethnic, racial, and geographic disparities in idiopathic thrombocytopenic purpura related mortality along the US-Mexico border from 1999 to 2020

Abstract Background: Idiopathic thrombocytopenic purpura (ITP) is an autoimmune disorder marked by accelerated platelet destruction and impaired production, leading to variable bleeding risk and, in severe cases, life-threatening hemorrhage. While most cases of acute ITP in children are mild and self-limiting, research indicates that adults with ITP have a 1.3 to 2.2 times higher mortality rate than the general population. Additionally, although ITP can affect people of all ages and backgrounds, patterns of ITP-related death among those along the US-Mexico border, who often belong to diverse and underserved communities, remain poorly understood. Therefore, our study aims to analyze temporal trends and demographic differences in ITP-related mortality among those along the US-Mexico border. Methods: We analyzed the CDC WONDER Multiple Cause of Death database for ITP-related mortality (ICD-10: D69.3) in the US-Mexico Border Regions for all age-groups from 1999 to 2020. We computed crude mortality rates (CMRs) and age-adjusted mortality rates (AAMRs) per 100,000 population with 95% confidence intervals (CI) and stratified by years, sex, race/ethnicity, census regions, urbanization status, states, and age groups. Joinpoint regression estimated average annual percent changes (AAPCs) and annual percent changes (APCs). Results From 1999–2020, 15,660 deaths were reported from ITP in the US-Mexico Border Regions. The AAMR decreased from 0.29 in 1999 to 0.18 in 2020. The overall AAMR from 1999-2020 was 0.21 (AAPC: -3.03, p<0.000001). Men had higher overall AAMR (0.25) with an AAPC of -2.54, compared to women (0.19) with an AAPC of -3.65. NH Whites had the highest overall AAMR of 0.22 (AAPC: -2.84) while Hispanics had an AAMR of 0.18 (AAPC: -2.52). Regionally, the Midwest had the highest overall AAMR (0.23), followed by the West (0.22), the Northeast (0.21), and then the South (0.20). The age group 85+ showed the highest mortality (CMR: 4.02) followed by the 75-84 age group (CMR: 1.63). Rural areas had higher AAMR (0.24) compared to the urban areas (0.21). Majority of the deaths occurred in inpatient medical facilities (8,754 deaths, 55.90%). Among the states, Vermont (0.37), and Rhode Island (0.35) had the highest AAMR from 1999-2020. Conclusion: Between 1999 and 2020, ITP-related mortality along the US-Mexico border declined significantly, yet men, non-Hispanic Whites, and those living in the Midwest and rural areas experienced higher death rates. Moreover, older adults over the age of 75 faced a higher mortality burden than the other age groups. These findings underscore the importance of equitable access to specialized hematology care, particularly for elderly and other high-risk groups. Moreover, our findings warrant an essential need for standardized outpatient monitoring and rapid referral pathways for bleeding complications. Strengthening telehealth initiatives, enhancing cross-border cooperative care models, and implementing community-tailored education on ITP management could further lower mortality rates and help eliminate remaining disparities among those living along the US-Mexico border.