Age-Adjusted Mortality Trends in Acute Tubulointerstitial Nephritis by Gender, Race, and Census Region in the United States: A CDC-WONDER Study, 1999–2020

<b>Background:</b> Acute tubulointerstitial nephritis (ATIN) is a significant yet under-monitored cause of U.S. mortality, particularly among the elderly. This study anrackalyzed national trends and demographic disparities in age-adjusted mortality rates (AAMRs) from 1999 to 2020 to identify high-risk populations and inform public health policy. <b>Methods:</b> Using the CDC WONDER database, we conducted a retrospective analysis of 6872 ATIN-related deaths. AAMRs (per 100,000) were stratified by sex, race, and census region. Temporal shifts were quantified using Joinpoint regression to determine annual percentage changes (APC) and 95% confidence intervals (CIs). <b>Results:</b> The analysis revealed a distinct "V-shaped" mortality trend across the 22-year period. Following an initial decline from 1999 to 2013, AAMRs rose sharply through 2020. Males experienced a slightly steeper recent increase (9.90%) compared to females (9.50%). While Black/African American individuals initially had higher mortality rates, a significant surge in deaths among Non-Hispanic White individuals after 2013 (APC 10.42%) led to a convergence of mortality rates between the two groups by 2020. Geographically, the Midwest (APC 12.08%) and the South saw the most pronounced recent increases, whereas the West showed a sustained upward trend beginning as early as 2008. <b>Conclusions:</b> There has been a concerning reversal in ATIN-related mortality trends in the United States over the last decade. The convergence of racial mortality rates and significant regional variations suggest that shifting healthcare access, environmental factors, or medication exposure patterns (such as polypharmacy) warrant urgent investigation to mitigate this rising public health burden.