Background Accidental hypothermia (AH) has higher incidence and mortality in geriatric populations. Japan has a rapidly ageing population, and little is known about the epidemiology of hypothermia in this country.
Methods We created an AH registry based on retrospective review of patients visiting the ED of 12 institutions with temperature ≤35°C between April 2011 and March 2016. The severity of AH was classified as mild (≤35, ≥32°C), moderate (<32, ≥28°C) or severe (<28°C). The relationship between in-hospital mortality and severity of AH was assessed using a multivariable logistic regression analysis.
Results A total of 572 patients were registered in this registry and 537 patients were eligible for our analysis. The median age was 79 (IQR 66–87) years and the proportion of men was 51.2% (273/537). AH was more likely to occur in elderly patients aged ≥65 years (424/537, 80.0%) and in indoor settings (418/537, 77.8%). The condition most frequently associated with AH, irrespective of severity, was acute medical illness. A lower mean outside temperature was associated with a higher prevalence of AH, and particularly severe AH (p for trend <0.001). The overall proportion of cases resulting in in-hospital death was 24.4% (131/537), with no significant difference between severity levels observed in a multivariable logistic regression analysis (severe group (37/118, 31.4%) vs mild group (42/192, 21.9%), adjusted OR (AOR) 1.01, 95% CI 0.61 to 1.68; and moderate group (52/227, 22.9%) vs mild group, AOR 1.11, 95% CI 0.58 to 2.14).
Conclusion Active prevention and intervention should occur for this important public health issue.
- environmental medicine
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Contributors TM contributed to the study concept and design, analysis and interpretation of the data, drafting of the manuscript and critical revision of the manuscript. SM, NE, NM, YohO, TJ, YS, NO, MW, MN, AT, YF and YosO collected the data and contributed to the study concept and design and the interpretation of the data, and the critical revision of the manuscript. TK and BO contributed to the study concept and design, and the critical revision of the manuscript. All authors read and approved the final manuscript.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Patient consent Not required.
Ethics approval Kyoto Prefectural University of Medicine.
Provenance and peer review Not commissioned; externally peer reviewed.
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