Intended for healthcare professionals


Cognitive dysfunction after concussion

BMJ 1998; 316 doi: (Published 14 March 1998) Cite this as: BMJ 1998;316:865

Authors did not to comment on the single truly significant result

  1. Mark W J Strachan, Clinical research fellow,
  2. Brian M Frier, Consultant physician,
  3. Ian J Deary, Professor of differential psychology
  1. Department of Diabetes, Royal Infirmary of Edinburgh, Edinburgh EH3 9YW
  2. Department of Psychology, University of Edinburgh, Edinburgh EH8 9JZ
  3. Psychological Laboratory, University of Copenhagen, 2300 Copenhagen S, Denmark
  4. Department of Neurology, Odense University Hospital, 5000 Odense C, Denmark

    EDITOR—Teasdale and Engberg examined the duration of cognitive dysfunction after concussive head injury in young men.1 We are concerned about their interpretation of some of the data presented. The observation that cognitive function was impaired up to one week after head injury was based on examination of only eight subjects, four of whom showed impaired performance. The authors placed considerable weight on this result even though the relative risk of cognitive impairment in the subjects with head injury was not significant by conventional criteria. It was additionally perplexing, given this non-significant result, that the 95% confidence interval did not pass through unity. Perhaps most surprising of all was that the authors failed to comment on the one truly significant result in that section of the paper—that impaired cognitive performance was shown …

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