National trends and disparities in mortality associated with peritonitis in the United States from 1999 to 2023

Abstract Background Peritonitis, including spontaneous bacterial peritonitis (SBP) in cirrhosis, peritoneal dialysis (PD)-associated peritonitis, and secondary surgical peritonitis, remains a major cause of morbidity and mortality. While SBP carries an in-hospital mortality of 20–30% and PD peritonitis continues to drive technique failure, national U.S. mortality patterns across demographic groups have not been fully characterized. We aimed to describe long-term peritonitis mortality trends and disparities in the United States from 1999 to 2023. Methods We performed a retrospective study using the CDC WONDER multiple cause-of-death database. Death certificates listing peritonitis (ICD-10 codes K65.0, K65.8, K65.9) as an underlying or contributing cause were included. Adults aged ≥ 45 years were analyzed. Crude and age-adjusted mortality rates (AAMRs per 100,000, standardized to the 2000 U.S. population) were calculated and stratified by sex, race/ethnicity, region, state, and urban-rural status. As CDC WONDER reports peritonitis only via K65.0 (acute peritonitis), K65.8 (other peritonitis), and K65.9 (unspecified peritonitis), we performed separate age-adjusted mortality rates (AAMRs per 100,000, standardized to the 2000 U.S. population) for each code and a sensitivity analysis excluding K65.9 (unspecified peritonitis). Joinpoint regression estimated annual percent change (APC) and average annual percent change (AAPC). Results From 1999 to 2023, 170,610 peritonitis-related deaths occurred, with an overall AAMR of 5.61/100,000. Mortality declined from 1999 to 2010 (APC − 2.72%), then increased thereafter (APC + 1.09%). Men had higher AAMRs than women, though the sex gap narrowed after 2010. Mortality was highest in American Indian/Alaska Native and Black populations, and lowest among Asian/Pacific Islanders. Rural residents had higher rates than metropolitan populations, with sharper increases after 2010. Regionally, the West had the highest AAMRs, while the Northeast remained the lowest. Mortality rose sharply with age, with recent increases particularly in middle-aged adults. Conclusion U.S. peritonitis mortality declined until 2010 but has since resurged, disproportionately affecting men, rural residents, and racial/ethnic minorities. These findings highlight the need for targeted interventions, improved infection prevention, and equity-focused strategies to reverse adverse trends and reduce disparities.