Early clinical predictors of amputation in frostbite: injury depth and extent for admission risk stratification

Early identification of patients at high risk of amputation remains a major challenge in frostbite management, particularly in resource-limited settings where advanced imaging may not be readily available. We aimed to identify admission predictors of amputation in a predominantly migrant frostbite cohort and secondarily evaluated the prognostic value of the Prognostic Nutritional Index (PNI) and neutrophil-to-lymphocyte ratio (NLR). We conducted a retrospective cohort study of consecutive patients admitted with frostbite to a tertiary referral hospital in eastern Turkey between January 2020 and December 2025. Demographic, clinical, and laboratory variables recorded at admission were compared between patients with and without amputation. Predictive performance was evaluated using receiver operating characteristic (ROC) analysis and multivariable logistic regression. Because frostbite degree demonstrated quasi-complete separation with the outcome, its independent effect was assessed using Firth penalized logistic regression. A total of 128 patients were included, of whom 126 (98.4%) were foreign nationals. Amputation was performed in 54 patients (42.2%). Frostbite degree was the strongest admission predictor of amputation, with 53 of 65 patients (81.5%) with third-degree frostbite requiring amputation compared with only 1 of 63 patients (1.6%) with first- or second-degree injuries (AUC 0.910, 95% CI 0.864–0.956). Frostbite extent (%TBSA) remained independently associated with amputation in multivariable analysis (adjusted OR 2.23, 95% CI 1.59–3.32; p < 0.001), and combining frostbite degree with %TBSA achieved the highest predictive performance (AUC 0.948, 95% CI 0.910–0.985). Although CRP, NLR, albumin, and PNI differed significantly between groups in univariable analyses, none remained independent predictors after adjustment for injury severity. In patients with frostbite, admission risk of amputation is primarily determined by injury depth and extent. Simple bedside assessment of frostbite degree and %TBSA provides robust early risk stratification, whereas inflammatory and nutritional biomarkers offer limited additional prognostic value beyond clinical evaluation. These findings may facilitate early identification of patients at high risk of amputation, particularly in resource-limited emergency settings and regions managing migration-related cold injuries.