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Another CT Prediction Rule for Head Injury
How sensitive should a rule be?
The New Orleans Criteria and the Canadian CT Head Rule — two externally validated prediction rules for use of computed tomography (CT) in patients with minor head injury — apply only to patients who have had loss of consciousness. Many patients with minor head injury do not have such a history, but clinicians still must decide whether a CT scan is needed. Dutch investigators used risk factors from studies of the two previous prediction rules to develop a more widely applicable rule.
The researchers prospectively enrolled 3181 patients who presented within 24 hours of blunt head injury and who had a Glasgow Coma Scale score of 13 or 14 or a score of 15 along with at least one risk factor (e.g., vomiting). Head CT performed according to published Dutch guidelines detected intracranial traumatic findings in 7.6% of patients. Overall, 0.5% of patients underwent neurosurgical treatment.
The authors used these findings to develop a prediction rule consisting of 10 major and 8 minor criteria. Internal validation indicated that if only patients with either one major criterion or two minor criteria underwent CT scanning, 96% of lesions would have been detected (sensitivity), and no cases requiring neurosurgical intervention would have been missed. Specificity was 25%. The 4% of lesions that would not have been detected included skull fracture (both depressed and linear), acute subdural hematoma, subarachnoid hemorrhage, and intraparenchymal bleed.
Comment: Emergency physicians in the U.S. likely would not agree to use a diagnostic scheme that could miss the types of lesions listed above. In fact, most U.S. practitioners would admit patients with these lesions for observation even if neurosurgical treatment were not warranted. Finally, telling patients that they might have bleeding in their brains but that it doesn’t matter is unthinkable.
— J. Stephen Bohan, MD, MS, FACP, FACEP
Published in Journal Watch Emergency Medicine April 27, 2007
Citation(s):
Smits M et al. Predicting intracranial traumatic findings on computed tomography in patients with minor head injury: The CHIP prediction rule. Ann Intern Med 2007 Mar 20; 146:397-405.
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