Correspondence

Indications for Computed Tomography after Minor Head Injury

N Engl J Med 2000; 343:1570-1571November 23, 2000

Article

To the Editor:

The carefully done and clearly documented study by Haydel and colleagues (July 13 issue)1 represents important progress in refining criteria for the use of computed tomography (CT) in patients with minor head injury that were originally proposed by me and others.2-4 However, I believe a word of caution is in order. Their claim that the seven criteria they used had a sensitivity of 100 percent must be viewed with some skepticism. I have encountered exceptions to their rule that these findings always accompany abnormal CT scans in patients with minor head injury. Even though such exceptions must be quite rare, the failure to identify even a single intracranial hematoma would have an enormous impact on outcomes and costs. I would also be reluctant to claim that the use of this approach could substantially reduce health care expenditures until many more patients, and the actual costs of their care, have been studied.

Sherman C. Stein, M.D.
University of Pennsylvania, Philadelphia, PA 19104

4 References

1. 1

   Haydel MJ, Preston CA, Mills TJ, Luber S, Blaudeau E, DeBlieux PMC. Indications for computed tomography in patients with minor head injury. N Engl J Med 2000;343:100-105
   Full Text | Web of Science | Medline

2. 2

   Stein SC, Ross SE. Minor head injury: a proposed strategy for emergency management. Ann Emerg Med 1993;22:1193-1196
   CrossRef | Web of Science | Medline

3. 3

   Stein SC. Management of minor closed head injury. Neurosurg Q 1996;6:108-115
   CrossRef | Web of Science

4. 4

   Ingebrigtsen T, Romner B, Kock-Jensen C. Scandinavian guidelines for initial management of minimal, mild, and moderate head injuries. J Trauma 2000;48:760-766
   CrossRef | Web of Science | Medline

To the Editor:

In the study by Haydel and colleagues, the predictive variables in phase 1 were well standardized, but there was no assessment of the interobserver agreement, and some potentially valuable findings were apparently not evaluated: the mechanism of injury and the presence or absence of chronic alcohol abuse, signs of basal skull fracture, and signs of open skull fracture.1-5 Although the outcome measure of a finding of any acute traumatic intracranial lesion on CT was well defined, it was certainly not a clinically important outcome in terms of patient care. The 909 patients included in the validation cohort in phase 2 made up a relatively large sample, but there were far too few clinically important outcomes in this group for sensitivity to be measured with an acceptably narrow 95 percent confidence interval. Fewer than six patients required surgery, so the 95 percent confidence interval for sensitivity was 54 to 100 percent. Finally, the specificity of the set of criteria used by Haydel et al. is so low that 77 percent of patients who present with a score of 15 on the Glasgow Coma Scale would require CT. This would actually lead to an increase in use of CT at most Canadian and European facilities.

Ian G. Stiell, M.D.
University of Ottawa, Ottawa, ON K1H 8M5, Canada

Andreas Laupacis, M.D.
Institute for Clinical Evaluative Studies, Toronto, ON M4N 3M5, Canada

George A. Wells, Ph.D.
University of Ottawa, Ottawa, ON K1H 8M5, Canada

for the Canadian CT Head and Cervical-Spine Study Group

5 References

1. 1

   Wasson JH, Sox HC, Neff RK, Goldman L. Clinical prediction rules: applications and methodological standards. N Engl J Med 1985;313:793-799
   Full Text | Web of Science | Medline

2. 2

   Feinstein AR. Clinimetrics. New Haven, Conn.: Yale University Press, 1987.
   

3. 3

   Laupacis A, Sekar N, Stiell IG. Clinical prediction rules: a review and suggested modifications of methodological standards. JAMA 1997;277:488-494
   CrossRef | Web of Science | Medline

4. 4

   Stiell IG, Wells GA. Methodologic standards for the development of clinical decision rules in emergency medicine. Ann Emerg Med 1999;33:437-447
   CrossRef | Web of Science | Medline

5. 5

   McGinn TG, Guyatt GH, Wyer PC, Naylor CD, Stiell IG, Richardson WS. Users' guide to the medical literature. XXII. How to use articles about clinical decision rules. JAMA 2000;284:79-84
   CrossRef | Web of Science | Medline

To the Editor:

Although the aim of the study by Haydel et al. was to reduce the number of CT scans obtained in patients with minor head injuries, it may have the opposite effect. If we can safely forgo CT scanning in patients who do not have any of the findings listed in the study, must we obtain CT scans in patients who do have one of these findings? For example, does every patient with “physical evidence of trauma above the clavicles” require CT of the head? This study does not identify the patients for whom CT is indicated. Rather, it identifies a group of patients for whom scanning is not indicated. Determining when scanning is indicated requires consideration of the likelihood of an abnormal finding, the effect of an abnormal finding on the patient's outcome, and the costs and risk of scanning, including the costs of false positive results. A nonzero yield of an abnormal finding is not sufficient to justify the use of an expensive study.

Michael A. Kohn, M.D., M.P.P.
Thomas B. Newman, M.D., M.P.H.
University of California, San Francisco, San Francisco, CA 94143

Author/Editor Response

Dr. Haydel replies:

To the Editor: Our goal was to derive and validate a set of bedside findings to identify patients with minor head injury who could safely forgo CT of the head. In the United States, patients with any loss of consciousness as a result of trauma routinely undergo CT. We evaluated only patients who had a loss of consciousness as a result of trauma, a normal score on the Glasgow Coma Scale, and normal findings on a brief neurologic examination; therefore, our findings should not be extrapolated to those without a loss of consciousness. Previous studies have shown that 6 to 9 percent of patients with minor head injury have evidence of intracranial injury on CT and that certain bedside findings are 100 percent sensitive in identifying those requiring neurosurgical intervention but are less sensitive in identifying all patients with an abnormal CT scan.1-3 Patients with even small subdural hematomas or isolated cerebral contusions are typically admitted for observation; therefore, the outcome measure in our study was evidence of intracranial injury on CT, not neurosurgical intervention.

We selected the items evaluated after a review of the literature, especially studies of patients who had a normal score on the Glasgow Coma Scale. A history of chronic alcohol abuse was not a significant variable in any of the studies; the mechanism of injury was significant in one.4 Signs of basilar or open skull fracture were included as evidence of trauma above the clavicles. As stated in our article, to determine the reproducibility of the clinical data, 50 patients were examined for the presence or absence of any of the seven findings by a second physician (extent of agreement between observers, 92 percent; κ=0.78).

In the validation phase, we found that the presence of any of seven findings identified by recursive partitioning (headache, emesis, an age of more than 60 years, drug or alcohol intoxication, seizure, short-term memory deficits, or physical evidence of trauma above the clavicles) was 100 percent sensitive in identifying patients with intracranial injury on CT scanning. Applying the seven-item guideline to our group of patients would have reduced the need for CT by 22 percent without failing to identify any patients with an abnormal CT scan.

In countries where CT is not readily available and patients with minor head injury typically do not undergo CT scanning, the application of these guidelines may increase the use of CT, but it is unlikely that patients with evidence of intracranial injury that is detectable on CT scanning would fail to be identified. As we stated in our conclusions, “the lower limit of the confidence interval [95 percent] indicates the possibility of missing an intracranial lesion that would be detected by CT scanning.” We look forward to the validation and further refinement of these findings at other centers.

Micelle J. Haydel, M.D.
Louisiana State University Health Science Center at New Orleans, New Orleans, LA 70112

4 References

1. 1

   Miller EC, Derlet RW, Kinser D. Minor head trauma: is computed tomography always necessary? Ann Emerg Med 1996;27:290-294
   CrossRef | Web of Science | Medline

2. 2

   Miller EC, Holmes JF, Derlet RW. Utilizing clinical factors to reduce head CT scan ordering for minor head trauma patients. J Emerg Med 1997;15:453-457
   CrossRef | Medline

3. 3

   Nagy KK, Joseph KT, Krosner SM, et al. The utility of head computed tomography after minimal head injury. J Trauma 1999;46:268-270
   CrossRef | Web of Science | Medline

4. 4

   Jeret JS, Mandell M, Anziska B, et al. Clinical predictors of abnormality disclosed by computed tomography after mild head trauma. Neurosurgery 1993;32:9-15
   CrossRef | Web of Science | Medline

Citing Articles (6)

Citing Articles

1. 1

   Cherri Hobgood, Susan Promes, Ernest Wang, Risa Moriarity, Deepi G. Goyal. (2008) Outcome Assessment in Emergency Medicine—A Beginning: Results of the Council of Emergency Medicine Residency Directors (CORD) Emergency Medicine Consensus Workgroup on Outcome Assessment. Academic Emergency Medicine 15:3, 267-277
   CrossRef

2. 2

   Kay M??ller, Will Townend, Nicola Biasca, Johan Und??n, Knut Waterloo, Bertil Romner, Tor Ingebrigtsen. (2007) S100B Serum Level Predicts Computed Tomography Findings After Minor Head Injury. The Journal of Trauma: Injury, Infection, and Critical Care 62:6, 1452-1456
   CrossRef

3. 3

   F. Nataf. 2007. Traumatismes cranio-encéphaliques et vertébro-médullaires. , 389-416.
   CrossRef

4. 4

   Peter Biberthaler, Ulrich Linsenmeier, Klaus-Juergen Pfeifer, Michael Kroetz, Thomas Mussack, Karl-Georg Kanz, Eduard F.J. Hoecherl, Felix Jonas, Ingo Marzi, Phillip Leucht, Marianne Jochum, Wolf Mutschler. (2006) SERUM S-100B CONCENTRATION PROVIDES ADDITIONAL INFORMATION FOT THE INDICATION OF COMPUTED TOMOGRAPHY IN PATIENTS AFTER MINOR HEAD INJURY. SHOCK 25:5, 446-453
   CrossRef

5. 5

   David Rosengren, Sean Rothwell, Anthony FT Brown, Kevin Chu. (2004) The application of North American CT scan criteria to an Australian population with minor head injury. Emergency Medicine Australasia 16:3, 195-200
   CrossRef

6. 6

   Kay Müller, Knut Waterloo, Bertil Romner, Knut Wester, Tor Ingebrigtsen. (2003) Mild Head Injuries: Impact of a National Strategy for Implementation of Management Guidelines. The Journal of Trauma: Injury, Infection, and Critical Care 55:6, 1029-1034
   CrossRef