Head injury: hypothermia reduced death and severe disability

Clinical bottom line (level 1a)

  1. Patients with moderate to severe closed head injuries who received immediate hypothermia compared with none were less likely to die or have severe disability (NNT = 4 at 3 months) .
Signorini and Alderson: Cochrane Library 1999; 3: -
Expires October 2003

The study

Systematic review of all randomised controlled trials of
  • Patients: moderate or severe closed head injury requiring hospitalisation
  • Intervention: mild hypothermia (local or systemic cooling to a target temperature of at most 34-35 C for at least 12 hours) compared with open or normothermia
  • Outcome: death, severe disability


    • Articles found in all languages using Cochrane Injuries Group trial registry and EMBASE, ? to 1998 (search terms: hypotherm* or normotherm* or cool* or cold* or temperature ) and hand-searching conference proceedings and reference lists of relevant articles. Leading investigators in the field were contacted for information about other studies.

    Selection criteria: by 2 independent reviewers: see above and further detailed in text
    Appraisal criteria: adequacy of allocation concealment and the degree of blinding
    Articles excluded if:
    • on-going
    • confounding, improper randomisation or investigating a different intervention


    8 studies found involving 263 patients

    The evidence

    Outcome Time to outcome CER OR
    (95% CI)    		 NNT
    (95% CI)
    death (immediate hypothermia) 3 months 41/116
    (35.3%)    		 0.67
    (0.38 to 1.17)     		12
    (NNT = 6 to infinity;
    NNH = 27 to infinity)
    death or severe disability (immediate hypothermia) 3 months 49/79
    (62.0%)    		 0.40
    (0.22 to 0.75)     		4
    (3 to 14)

    Comments

    1. Few studies were found and most were small increasing the risk of publication bias.
    2. A large study is awaiting publication (NABIS:H) which will vastly affect these results.
    3. Only one study addressed delayed hypothermia in 33 patients - it is too small to provide certain results.

    Citation

    1. Signorini DF, and Alderson P: therapeutic hypothermia for head injury (Cochrane Review): Update Software. Cochrane Library 1999; 3: -
    Contributor: Chris Ball and Clare Wotton, October 1999
    Reviewer: Dirk Stengel

    Clinical Question.
    Patient isolated head injury
    Intervention or Exposure intentional hypothermia
    Comparison normothermia
    Outcome neurological disability, mortality