Clinical Prediction of Emergency Cranial Computed Tomography Results,☆☆,

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Abstract

Study purpose: To determine the ability of clinicians to predict the results of emergency head computed tomography (CT) scans. Methods: Clinicians requesting cranial CT scans from the emergency department prospectively filled out a form detailing their patients' complaints, possible diagnoses, and the likelihood of finding those diagnoses on CT. The results of the scans were catalogued according to diagnosis and classified as acutely abnormal, chronically abnormal, or normal. Results: Analysis of 536 consecutive patients showed a significant direct correlation between clinical prediction of CT abnormality and scan results. No definite differences in the ability to predict scan results were observed among different physician training levels. Thirty-six patients had acute abnormalities on CT despite a clinical prediction of remote or low likelihood. Conclusion: Although clinical predictions of CT abnormality correlate with actual CT results, the correlation is not adequately refined to rely on for selection of patients for emergency cranial CT scans.

[Reinus WR, Zwemer FL Jr: Clinical prediction of emergency cranial computed tomography results. Ann Emerg Med June 1994;23:1271-1278.]

Section snippets

INTRODUCTION

Many studies have evaluated the usefulness of emergency cranial computed tomography (CT) for a variety of clinical problems, including trauma, headaches, ischemia, and seizures.1, 2, 3, 4, 5, 6, 7, 8, 9, 10 A large proportion of the scans that are obtained to evaluate these problems show no acute abnormality. Most agree, however, that it is important to maintain a low threshold for obtaining CT to avoid missing significant but clinically silent pathology.4, 5, 6, 7, 8, 11, 12, 13, 14

Although

MATERIALS AND METHODS

Cases were collected between January 14, 1992, and December 6, 1992, from a Level II emergency department that treats 26,000 patients per year and is in a major teaching hospital. In all patients for whom a head CT was requested, clinicians filled out a form before obtaining the CT. Data entered on the form included the clinical indication for the CT, the abnormality or abnormalities that the clinician suspected the scan would show, the clinician's prediction of the likelihood of finding an

RESULTS

We collected data on 550 consecutive patients who underwent cranial CT out of the ED. Fourteen cases had incomplete forms and so were excluded from analysis. We assumed a missing at random basis for the data and used the remaining cases for analysis.

Analysis of Prediction: All Cases The correlation between predicted CT results and actual CT results is given for the entire sample (Table 2). There were 123 CT scans (22.9%) with acute abnormalities and 197 CT scans (36.8%) with chronic

DISCUSSION

Our data show that clinicians' predictions of acute abnormalities on cranial CT generally coincide with the findings on the scan. Despite this fact, 29.2% of the acutely positive scans were in the remote or low prediction categories. In the sample of patients whose neurologic examinations were negative, 36.7% of the acutely positive scans were in the remote or low likelihood categories, a higher percentage than for the entire sample. This percentage increase is statistically significant (χ2, P

CONCLUSION

Although our data show a definite relationship between prediction of CT abnormality and actual CT result, it clearly is not adequately refined to allow patient selection for CT based solely on clinical impression. Previous studies have argued for the use of various algorithms to guide clinicians in choosing patients for CT.11, 12, 13, 15, 16 Others have suggested the liberal use of CT in ED patients with even minimal head trauma.4, 5, 6, 7, 8, 14 To date, no study has been able to show perfect

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  • Cited by (0)

    From the Department of Radiology* and the Emergency Department, Department of Internal Medicine, Jewish Hospital, Washington University Medical Center, St Louis, Missouri.

    ☆☆

    Address for reprints: William R Reinus, MD, Associate Professor, Jewish Hospital, Mallinckrodt Institute of Radiology, Washington University Medical Center, 216 S Kingshighway, St Louis, Missouri 63110, 314-454-7400, Fax 314-454-5262

    Reprint no. 47/1/55407

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