Hypothermia as a cause of death in British Columbia, 1998−2012: a descriptive assessment

Background: Hypothermia can result from exposure to cold or as a consequence of underlying physiologic vulnerabilities. Who, where, when and how British Columbians (and Canadians) die of hypothermia have received little research attention. The objective of this study was to describe the epidemiology of mortality due to hypothermia among residents of British Columbia.

Methods: We examined all records in the death registry of the British Columbia Vital Statistics Agency between 1998 and 2012 that had an underlying or contributing cause of death coded for hypothermia or exposure to excessive natural cold.

Results: Hypothermia or exposure to excessive natural cold was found to be the underlying or contributing cause in 384 deaths between 1998 and 2012. Mean age of decedents was 52 (SD 20.78) years and 73.2% were male. The annual death rate for hypothermia increased with age, ranging from 0.3 per 100 000 population among people aged 1−34 years to 1.6 per 100 000 population among those older than 75 years of age. The highest annual death rate occurred among older males (2.1 per 100 000 population) followed by older females (1.3 per 100 000 population). Although hypothermia-related deaths occurred year-round, 45.9% occurred during winter months (December, January and February) and, in particular, on days with lower temperatures (mean 0.56°C). Use of alcohol (40.1%) and other psychoactive substances (22.7%) were the most common additional causes of death identified among deaths due to hypothermia. Areas of British Columbia with the lowest population density or lowest socioeconomic status were found to have the highest crude hypothermia-related mortality rates.

Interpretation: Our results showed that older people are at higher risk of hypothermia-related death. Among residents of British Columbia who died of hypothermia, the most frequent additional causes of death were alcohol and nonalcohol psychoactive substances. However, further assessment of both the occurrence and determinants of mortality due to hypothermia are needed to inform measures to reduce its impact.