Post-2020 trajectory of adult necrotizing fasciitis-associated mortality in the United States, 2003–2024: a national death-certificate study

Abstract Background Necrotizing fasciitis is an uncommon but life-threatening bacterial soft-tissue infection. Prior U.S. mortality analyses reported findings through 2013 and 2020, leaving the subsequent national trajectory uncharacterized. Methods We analyzed final CDC WONDER/NCHS Multiple Cause of Death data for U.S. adults aged 25 years or older during 2003–2024, identifying deaths with ICD-10 M72.6 anywhere on the death certificate. Annual age-adjusted mortality rates (AAMRs) per 100,000 used year-specific population denominators and the 2000 U.S. standard population. Exploratory interrupted time-series models estimated level and slope differences beginning in 2020, with sensitivity analyses for baseline shape and serial correlation. Results Adult necrotizing fasciitis-associated deaths numbered 1,506 in 2019, 2,056 in 2022, and 1,995 in 2024. AAMRs per 100,000 were 0.583, 0.795 (the highest observed annual rate), and 0.740, respectively. The primary segmented model estimated a 2020 level difference of 0.223 per 100,000 (95% CI, 0.142 to 0.304), with a slope difference of -0.002 per 100,000 per year (95% CI, -0.021 to 0.017). Positive level estimates persisted across sensitivity models, but the estimated 2024 difference from the projected pretrend depended on baseline specification. Secondary 2024-to-2019 and 2024-to-2022 rate ratios were 1.27 (95% CI, 1.18 to 1.36) and 0.93 (95% CI, 0.87 to 0.99), respectively. Conclusions Adult mortality in 2024 was lower than in 2022 but remained higher than in 2019. Exploratory models supported a higher fitted level beginning in 2020, with a model-dependent longer-term trajectory. These findings do not establish pandemic causation or a 2022 turning point.