Volume 22, Issue 5 (11-2019)                   J Arak Uni Med Sci 2019, 22(5): 100-111 | Back to browse issues page

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Gharibi M, Najafgholian S, Rafiee F, Nazemi A, Mansourizadeh E. The Sensitivity and Specificity of American College Of Emergency Medicine Guideline in Predicting the Need for Computed Tomography Scan in Patients with Mild Head Trauma. J Arak Uni Med Sci 2019; 22 (5) :100-111
URL: http://jams.arakmu.ac.ir/article-1-6062-en.html
1- Department of Emergency Medicine, Arak University of Medical Sciences, Arak, Iran.
2- Department Biostatistics and Epidemiology, School of Health, Scientific Research Center, Tehran University of Medical Sciences, Iran. , S.najafgholian@arakmu.ac.ir
3- Department Biostatistics and Epidemiology, School of Health, Scientific Research Center, Tehran University of Medical Sciences, Iran.
4- Neurosurgery Specialist, Vali-e-Asr Hospital of Arak, Arak University of Medical Sciences, Iran.
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In mild head trauma, 6%-9% of brain lesions were seen, with 0.4%-1% requiring surgery (1 and 2). Computed tomography (CT) increases the ability to detect, but causes unnecessary exposure to radiation [3-5]. For this reason, several rules such as Canadian CT Head Rule (CCHR), New Orlean Criteria (NOC) and National Emergency X- Radiography Utilization Study (NEXUS) have been developed. The American College Of Emergency Medicine (ACEM) has also provided a clinical guideline [6]. These criteria (a combination of criteria from several studies and the three mentioned rules) have been suggested, to examine the prediction power, sensitivity and specificity of determining the extent of brain injury in minor head trauma. This study examined the external validity, predictive value, sensitivity, and specificity of this clinical guideline for the need for CT in patients with mild head trauma.
Materials and Methods
This cross-sectional study was performed for 6 months on patients over 18 years old referred to the emergency department of Vali-e-Asr Hospital in Arak, Iran who met ACEM criteria for head CT scan for suspected mild head trauma. The inclusion criteria were: Having age 18 and above, head trauma in the past 6 hours, and meeting ACEM criteria. On the other hand, exclusion criteria were: Glasgow Coma Scale (GCS) score ≤13, age <18 years, unstable vital signs, pregnancy, clear skull fracture or depressed skull fracture.
Their demographic characteristics, clinical symptoms, trauma mechanism, physical injuries caused by head trauma, and history of drug abuse were recorded by a checklist. During hospitalization, their GCS was checked every two hours. Patients underwent treatment if there was a pathology in CT images, and those with no clear pathology were discharged after 6 hours and, followed up by phone for two weeks, and in case of any abnormality in the consciousness level, they were re-examined by CT scanning. Data analysis was conducted in SPSS v.18 and MEDCALC applications. Descriptive statistics as well as chi-squared test and t-test were used in analyzing data at 95% confidence interval. 
First rule of ACEM criteria to determine whether the head CT is needed is for patients with decreased consciousness level or post-traumatic memory loss and having following symptoms: Headache, vomiting, age over 60 years, drug or alcohol intoxication, trauma above the clavicles, post-traumatic seizure, GCS <2, focal neurological deficit and coagulation disorders. The second rule of ACEM criteria for head CT is related to patients with head injury without loss of consciousness or memory after trauma having following symptoms: Focal neurologic deficit, vomiting, severe headache, age over 65 years, basal skull fracture, GCS <2, coagulation disorders. Based on the two rules of ACEM criteria for head CT, patients first underwent CT according to the first rule and then based on the second rule. Afterward, they were compared with each other.
Of the 500 patients, 335 (67%) were male and 165 (33%) were female. Their mean age was 46.39±2.01 years (ranged from 13 to 95 years). Gender, type of accident, drug and alcohol abuse, coagulopathy, warfarin or enoxaparin use, level of consciousness at the time of hospital admission, and pedestrian being thrown to the road 2-3 meter when hit by the motorcycle/car were not significantly different between study groups; they were different only in subdural hematoma.
Based on the first rule, the sensitivity of ACEM guideline for predicting the need for CT scan in patients with mild head trauma was 100% with a specificity of 3.46% indicating that the guideline was highly sensitive in diagnosis of mild head trauma, but its specificity was low.
Based on the second rule, the sensitivity of ACEM guideline was 100% with a specificity of 6.71%. Moreover, the positive and negative predictive value 1.71 and 100, respectively. This indicates that this guideline has no diagnostic value.
The aim of this study was to evaluate the diagnostic method of ACEM clinical guideline for the need for CT in patients with mild head trauma having a GCS score of more than 13. The results showed that ACEM guideline in terms of predicting the need for CT in mild head trauma, had 100% sensitivity and specificity of 3.46 and 6.71% based on the first and seconds rules, respectively indicating its low specificity despite having high sensitivity.
Stiell et al. [10] examined CCHR and NOC in patients with minor head injury. They showed that both rules had equal sensitivity for predicting need for CT, but the specificity of CCHR was higher. In our study, the ACEM criterion was not able to predict the patients’ need for CT. Mata-Mbemba et al. [11] compared two rules of CCHR and NOC in patients with mild head trauma. They reported that Only the CCHR was significantly associated with important CT findings and had higher efficiency compared to NOC. In our study, despite the low specificity of the ACEM criterion, it did not reduce the need for CT in mild head trauma and was not consistent with the results of this study.
Many studies have been conducted and compared CCHR, NOC and Nexus criteria for CT in head trauma [12-15]. All have reported the high sensitivity of these criteria and their low specificity.

The ACEM guideline had high sensitivity to predicting the need for CT in patients with mild head trauma, but had very low specificity and positive/negative predictive value which makes it an unacceptable criterion for rejecting or performing head CT scan in these patients.
Ethical Considerations
Compliance with ethical guidelines

This study has an ethical approval obtained from Arak University of Medical sciences (code: IR.ARAKMU.REC.1396.227).
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
Authors' contributions
The authors observed the standards of writing based on the recommendations of the International Committee of Medical Journal Publishers.
Conflicts of interest
The authors declare no conflict of interest.
The authors would like to thank the patients and the Deputy for Research of Arak University of Medical sciences for their cooperation and support.

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Type of Study: Original Atricle | Subject: Internal
Received: 2019/05/1 | Accepted: 2019/10/28

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