title: Hypothermia in Adult ICUs: Changing Incidence But Persistent Risk Factor for Mortality.
abstract: BACKGROUND
  This study examined whether hypothermia (< 36.0°C) incidence among critically ill patients varied over time, the determinants of change, and the associated risk for ICU mortality.
  
  
  METHODS
  Interrupted time series analysis among adults admitted to ICUs in Calgary, Canada over 8.5 years. Changes in the incidence of hypothermia within the first 24 hours of ICU admission were modelled using segmented regression.
  
  
  RESULTS
  Among 15,291 first admissions to ICU, hypothermia incidence decreased from 29% to 21% during the study period. Implementation of a new temporal artery thermometer (TAT) was associated with the majority of the decrease in incidence (10%; 95% CI 7.1-13%; P < .0001). However, subgroup analysis revealed important differences between medical and surgical patients. Hypothermia incidence decreased among surgical patients before TAT implementation (0.4% per quarter, 95% CI 0.1-0.7%, P = .009), but not after, whereas in medical patients, the incidence increased after (1.0% per quarter, 95% CI 0.6-1.4%, P < .0001) but not before TAT implementation. Segmented logistic regression suggested that increases in the proportion of patients with non-traumatic neurologic admission diagnoses were associated with hypothermia incidence among medical patients, whereas there was no measurable clinical factor associated with the observed time trends among surgical patients. Hypothermia at ICU admission was independently associated with ICU mortality in medical and surgical patients throughout the entire study.
  
  
  CONCLUSIONS
  The incidence of hypothermia at ICU admission was dependent on medical versus surgical status, and the method of non-invasive temperature measurement, but was persistently associated with ICU mortality.
authors.affiliation: Department of Critical Care Medicine, University of Calgary and Alberta Health Services, Calgary, Alberta, Canada Department of Community Health Sciences, University of Calgary, Calgary, Alberta, Canada daniel.niven@albertahealthservices.ca.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Niven
authors.affiliation: Department of Critical Care Medicine, University of Calgary and Alberta Health Services, Calgary, Alberta, Canada Department of Community Health Sciences, University of Calgary, Calgary, Alberta, Canada Department of Medicine, University of Calgary and Alberta Health Services, Calgary, Alberta, Canada.
authors.forename: Henry T
authors.initials: HT
authors.lastname: Stelfox
authors.affiliation: Department of Critical Care Medicine, University of Calgary and Alberta Health Services, Calgary, Alberta, Canada Department of Community Health Sciences, University of Calgary, Calgary, Alberta, Canada Department of Medicine, University of Calgary and Alberta Health Services, Calgary, Alberta, Canada Department of Medicine, Royal Inland Hospital, Kamloops, British Columbia, Canada.
authors.forename: Kevin B
authors.initials: KB
authors.lastname: Laupland
mesh_terms: D000328:Adult; D000368:Aged; D000416:Alberta / Q000453:epidemiology; D016638:Critical Illness / Q000401:mortality; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D007035:Hypothermia / Q000209:etiology / Q000401:mortality*; D015994:Incidence; D007362:Intensive Care Units / Q000639:trends*; D065186:Interrupted Time Series Analysis; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors
keywords: hypothermia; incidence; intensive care unit; mortality; temperature; thermometer