Abstract
BACKGROUND: Sepsis is a leading cause of mortality among older adults, and atrial fibrillation (AF), as a common comorbidity, significantly increases the risk of adverse outcomes. This study aimed to investigate nationwide mortality trends, racial and regional disparities, and contributing factors in adults aged 55–84 years with sepsis-AF. METHODS: We analyzed CDC WONDER mortality data for adults aged 55–84 years (1999–2020), defining cases as deaths with sepsis (A40–A41) as the underlying cause and AF (I48) listed as a contributing condition anywhere on the certificate. Individuals aged 55–84 years with sepsis-AF noted on death certificates were included. Age-adjusted mortality rates (AAMR) were calculated based on the 2000 US standard population. Temporal trends in AAMR were assessed using Joinpoint regression, and analyses were stratified by race and geographic region. RESULTS: The overall AAMR increased significantly from 0.64 to 1.57 per 100,000 (145% rise; average annual percent change [AAPC] = 4.49%). Marked disparities were observed: males exhibited 30.7% higher mortality than females by 2020; Black individuals showed higher mean AAMR throughout the study period though rates converged statistically by 2020; and the South recorded the highest regional AAMR while the West showed the largest relative increase. AAMR surged across all groups in 2020, coinciding with the COVID-19 pandemic. CONCLUSIONS: Mortality due to sepsis-AF among older adults aged 55–84 years in the US has exhibited a sustained upward trajectory, accompanied by significant demographic and regional disparities. Targeted public health interventions are essential to address these inequalities and mitigate mortality in high-risk populations. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12889-026-27023-x.