'Cold and lonely': emergency presentations of patients with hypothermia to a large Australian health network

Extreme heat is a public health priority in Australia with the health effects of cold poorly studied. A record-breaking cold winter prompted an institutional investigation into the epidemiology and outcomes of hypothermic presentations.

To describe the clinical and epidemiological characteristics of hypothermic emergency presentations including patient outcomes as well as gaps in practice.

This was a retrospective cohort observational study of hypothermic emergency presentations between 7 July 2009 and 1 September 2016 with a temperature of ≤35°C. Independent predictors for inpatient mortality and characteristics of exposure versus non-exposure presentations were evaluated.

There were 217 patients with 226 presentations comprising male gender in 54%, median age 76.5 years (interquartile range (IQR) 53-88) and median initial temperature 33.3°C (IQR 31.2-34.3°C). Non-exposure presentations being found indoors, accounted for 78% overall, with elderly persons ≥65 years (P = 0.002) and multimorbidity (Charlson comorbidity index ≥4, P = 0.013) overrepresented in this subgroup. Among the non-exposure cohort, 55% were pensioners and 42% lived alone. Inpatient mortality was 11% overall and significantly higher in non-exposure versus exposure cohorts (16 vs 2%, P = 0.01). Independent predictors of inpatient mortality included heart failure (P = 0.04), metastatic malignancy (P < 0.01), chronic kidney disease (P < 0.05) and sepsis (P < 0.01). In contrast, exposure-related presentations were characterised by younger patients with intoxication due to alcohol and/or illicit drugs and psychiatric comorbidity.

Hypothermia is a marker of clinical and socioeconomic vulnerability. The dominant presentation of the elderly patient with multimorbidity, and few social supports being found indoors, raises broader questions around the social determinants of health.