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

Summary

We surveyed 1,250 servicemen in northern subarctic/alpine garrisons to profile frostbite and evaluate CIVD screening. New recruits, southern origin, and field operational training increased risk; VO₂ max and adiposity did not. A unitless CIVD index showed good discrimination (AUC 0.778), supporting targeted prevention.

Abstract

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.

Introduction

Frostbite is a frequent cold injury in military units operating in severe climates, particularly in northern subarctic/alpine regions where low ambient temperature, wind chill, moisture, and prolonged outdoor tasks converge to impair peripheral perfusion and tissue viability^1,2. In China, units stationed in Heilongjiang and northern Inner Mongolia routinely face such hazards during winter field activities, and cold weather injuries, including frostbite, contribute measurably to non-battle injuries and lost duty time in armed forces worldwide³. Although diagnosis is largely clinical, eff....

Protocol

The protocol was approved by the Ethics Committee of the General Hospital of the Northern Theater Command (Approval No. Y(2020)094). All procedures involving human participants were conducted in accordance with the ethical standards of the institutional and/or national research committees and with the 1964 Helsinki Declaration and its later amendments. Written informed consent was obtained from all participants prior to data collection.

Participants selection
A total of 1,268 servicemen stationed in northern subarctic/alpine garrisons were screened; 1,250 provided valid questionnaires, yielding an effective response r....

Results

Questionnaire Administration (Epidemiology and Characteristics)
Among 1,250 servicemen surveyed, 688 (55.04%) reported frostbite. Of these, 620 (90.12%) were first-degree and 68 (9.88%) were second-degree. The most frequently affected sites were the feet (78.13%) and hands (75.00%), followed by ears (17.71%) and face (15.63%). Frostbite episodes clustered between November and February, when ambient temperatures ranged from -20 °C to -50 °C. Local symptoms typically appeared after 55.56 &#.......

Discussion

China's northern subarctic/alpine garrisons are strategically critical, and extreme winter conditions make frostbite a leading non-battle injury. In this cohort, the incidence was 55.04%, exceeding most Chinese reports (11.3-38.5%) and Nordic data. The higher rate plausibly reflects sample composition, task profiles, and environment: our participants were frontline border-defense soldiers routinely exposed to -20 to -50 °C with prolonged outdoor duties²³. Conversely, the incidence remaine.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Circulating Water Bath (Cold)	Julabo, Germany	11223-CWB-Cold	Used for maintaining 8°C temperature during the cold immersion phase in CIVD protocol.
Circulating Water Bath (Warm)	Julabo, Germany	11223-CWB-Warm	Used for maintaining 35°C temperature during the warm immersion phase in CIVD protocol.
Cold-Induced Vasodilation (CIVD) Protocol	Custom Lab Setup	CIVD-001	Standardized hand and foot cold immersion and rewarming protocol to induce CIVD for testing.
Harpenden-type Skinfold Caliper	Holtain Limited, UK	12345-HT	Calibrated skinfold caliper used for measuring subcutaneous fat at seven anatomical sites.
Motorized Treadmill (Bruce Protocol)	Trackmaster, UK	TM-3000-BP	Treadmill used for VO2 max assessment following the Bruce protocol with heart-rate/ECG monitoring.
NIST-Traceable Reference Thermometer	NIST, USA	5987-NT	For calibration checks to ensure accuracy of thermometers used in CIVD tests.
Skin-Temperature Sensors	Testo, Germany	67890-ST	Accuracy ± 0.1°C, 1 Hz data logger, used for measuring skin temperature during CIVD testing.
SPSS v21.0 Software	IBM, USA	N/A	Statistical software used for data processing and analysis. Employed for descriptive statistics, independent-samples t-tests, chi-square tests, and multivariable logistic regression analysis.
Tympanic Thermometer	Welch Allyn, USA	5200-TT	Used for accurate temperature measurement during CIVD protocol, ± 0.1°C accuracy.