Frostbite Prevalence, Risk Factors, and CIVD-Based Screening Among Servicemen Stationed in Northern Subarctic/Alpine Regions: A Cross-sectional Survey

Frostbite remains a common cold injury in military units operating in severe climates, yet the epidemiology and physiologic screening markers for vulnerable personnel are not fully characterized. We conducted a cross-sectional study of 1,250 male servicemen stationed in northern subarctic/alpine regions, combining a structured questionnaire with anthropometry (skinfolds), estimated maximal oxygen uptake (VO2 max; Bruce protocol), and a standardized hand/foot cold-induced vasodilation (CIVD) protocol. Frostbite was reported by 688 participants (55.0%), predominantly first-degree; feet (78.1%) and hands (75.0%) were most affected, with incidents clustering between November and February at -20°C to -50 °C. In multivariable models, recruit status, southern origin before enlistment, and participation in field operational training were associated with higher odds of frostbite, whereas subcutaneous fat and VO2 max were not independent predictors. A unitless CIVD index summarizing response timing and magnitude discriminated frostbite status with an area under the ROC curve (AUC) of 0.778; at the Youden cut-off, sensitivity was 70.5% and specificity was 85.5%. These findings indicate a high frostbite burden concentrated during winter operational activities and support the practical utility of a simple CIVD index to identify high-risk individuals for targeted prevention and training. Prospective studies that integrate detailed exposure metrics and protective-equipment use are warranted to refine prediction and evaluate prevention strategies.