Clinical and laboratory factors associated with in-hospital composite severe outcomes in patients with extremity necrotizing fasciitis: evidence from a 12-year single-center retrospective cohort

Extremity necrotizing fasciitis (NF) may deteriorate rapidly in hospital, yet pragmatic early risk stratification is difficult. We assessed admission clinical and laboratory factors associated with a clinically actionable in-hospital composite severe outcome. In this 12-year single-center retrospective cohort of adults with surgically confirmed extremity NF ( n = 122), baseline values were the earliest obtained at presentation. The primary endpoint was a post-baseline in-hospital composite of death, septic shock, or intensive care unit (ICU) admission. Adjusted associations were estimated using multivariable logistic regression, with age, sex, body mass index (BMI), and American Society of Anesthesiologists physical status (ASA) forced into the model; procalcitonin (PCT), lactate dehydrogenase (LDH), and lactate were modeled per doubling on the log₂ scale. A sensitivity model excluding lactate was also performed. Eighty patients (65.6%) developed the composite outcome; mortality was 4.1%, septic shock 60.7%, and ICU admission 48.4%. Independently associated factors were ASA class (aOR 2.74 per class), PCT (aOR 1.29 per doubling), LDH (aOR 2.52 per doubling), and lactate (aOR 2.54 per doubling). Excluding lactate, ASA, PCT, and LDH remained significant. Areas under the receiver operating characteristic curves (AUCs) were 0.830 (95% CI 0.751–0.892) for lactate, 0.785 (95% CI 0.701–0.854) for LDH, and 0.816 (95% CI 0.704–0.866) for PCT. Higher ASA class and elevated admission PCT, LDH, and lactate were independently associated with in-hospital severe outcomes in extremity NF and may support early risk stratification pending external validation.