Case series of non-freezing cold injury: epidemiology and risk factors.

Background: Non-freezing cold injury (NFCI) occurs when the peripheral tissue is cooled sufficiently that damage occurs, but not to the point of tissue freezing. Historically, the phenotype of the injuries studied was often severe, and it is unclear whether knowledge gained from these cases is entirely relevant to the frequently subtle injuries seen today.

Methods: We therefore sought to characterise a recent case series of 100 patients referred with suspected NFCI to a military UK NFCI clinic. Their demographics, medical history and situational risk factors leading to their injuries were analysed, and comparison was made between those subsequently diagnosed with NFCI (n=76) and those receiving alternate diagnoses (n=24).

Results: Statistically significant predisposing factors for NFCI in the UK service personnel (SP) were being of African-Caribbean ethnicity and having a short duration of service in the Armed Forces. Past or current smoking was not identified as a risk factor. Injuries were almost always suffered on training exercises (most commonly in the UK); being generally cold and being on static duties were statistically significant situational risk factors. Non-significant trends of risk were also found for having wet clothing, wet boots and immersion. Self-reported dehydration was not found to be a risk factor for NFCI.

Conclusions: Our demographic findings are in general agreement with those of previous studies. Our situational risk factor findings, however, highlight a pattern of NFCI risk factors to the modern UK SP: winter training exercises, when troops are generally cold and extremities often wet, with static duties frequently implicated in the disease mechanism.