Letter

Correcting outcome data for case mix in stroke medicine

BMJ 1996; 313 doi: 10.1136/bmj.313.7063.1005c (Published 19 October 1996)
Cite this as: BMJ 1996;313:1005.4

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Doctors who perform abortions for social reasons are social technicians

  1. David Barer, Professor of geriatric medicine,
  2. John Ellul, Research fellow,
  3. Caroline Watkins, Research coordinator
  1. Institute for the Health of the Elderly, Newcastle General Hospital, Newcastle upon Tyne NE4 OBE
  2. Aintree Stroke Unit, Fazakerley Hospital, Liverpool L9 7AL

    Structure and process should be audited, rather than outcomes

    EDITOR,—The method used by Richard J Davenport and colleagues to correct for differences in case mix before and after a stroke unit was set up could obscure genuine differences in outcomes due to changes in medical care.1 A logistic regression model containing 19 prognostic variables, whose coefficients are derived from the study itself, is almost certain to overfit the data, so that some differences that are due to treatment may be spuriously “explained” by adjustment for case mix. …

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