What factors predispose to frostbite?Factors that predispose to freezing and non-freezing cold injury include military activities, winter sports, and homelessness (box 1).4 In a large retrospective epidemiological review of frostbite injuries sustained over 12 years in the Canadian prairies, individual behaviour was an important contributor to overall risk. Forty six per cent of patients were intoxicated with alcohol, 17% had a psychiatric disorder, and 3% had used illicit drugs.5 Fingers, toes, noses, cheeks, ears, and male genitalia were most commonly affected by frostbite in all groups (in that order).6 A large cross sectional study over 19 years by the US army found that men of Afro-Caribbean descent were four times more likely than white men to sustain cold weather injuries.7Box 1 Predisposing factors General: Unusually cold weather, prolonged exposure to cold, inadequate clothing, inadequate use of appropriate clothing, homelessness, smoking, dehydration, old age, ethnic origin, high altitude Systemic disease: Peripheral vascular disease, diabetes, Raynaud’s disease, sepsis, previous cold injury Psychiatric illness Drugs: β blockers, sedatives, and neuroleptics Trauma: Any immobilising injury, but especially head and spinal injuries and proximal limb trauma that compromises the distal circulation Intoxication: Alcohol and illicit drug use