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CHIP (CT in Head Injury Patients) Prediction Rule

The CHIP prediction rule may be used as an aid to decide whether to perform a CT in minor head injury patients.
<40 years 0
40-60 years 1
≥60 years 10
Glasgow Coma Scale deterioration at 1 hr after presentation
None 0
1 point 1
≥2 points 10
Skull injury
Skull contusion = clinically significant discontinuity of the skin or extensive bruising
None 0
Skull contusion 1
Any injury denotes skull fracture, e.g. palpable discontinuity of skull, CSF leakage, raccoon eyes, bleeding from ear 10
Post-traumatic amnesia
Patient cannot recall entire traumatic event
None 0
2 to <4 hr 1
≥4 hr 10
Pedestrian or cyclist versus vehicle
No 0
Yes 10
Ejected from vehicle
No 0
Yes 10
Defined as an episode of emesis after the traumatic event
No 0
Yes 10
Anticoagulants uses
No 0
Yes 10
Post-traumatic seizure
Seizure witnessed or suspected after injury
No 0
Yes 10
Falling from the elevation
No 0
Yes 1
Persistent anterograde amnesia
Any short-term memory deficit
No 0
Yes 1
Neurologic shortage
Any abnormality on routine clinical neuro exam indicating a focal cerebral lesion
No 0
Yes 1
Loss of consciousness
No 0
Yes 1


Measured Factor
CHIP score
Measured Factor Disease
  • Head injury
Measured Factor Detail
It is used in patients at least 16 years old presenting within 24 hours of blunt head trauma and glasgow coma scale of 13–15 with at least one of the following loss of consciousness, short-term memory deficit, amnesia, seizure, vomiting, severe headache, intoxication, anticoagulant use or history of coagulopathy, external evidence of injury above the clavicles and neurologic deficit. The CHIP- CT uses major and minor factors to determine if the patient requires CT after head trauma.                                                                                                                          
Major criteria:                                                                                                                                                                                                                                                                                                                                                                                                                               
Pedestrian or cyclist versus vehicle.
Ejected from vehicle.
Post-traumatic amnesia ≥4 hours.
Clinical signs of skull fracture*.
GCS <15.
GCS deterioration ≥2 points (1 hour after presentation).
Use of anticoagulant therapy.
Post-traumatic seizure.
Age ≥60 years.
Minor criteria:
Fall from any elevation.
Persistent anterograde amnesia.
Post-traumatic amnesia of 2 to <4 hours.
Contusion of the skull.
Neurologic deficit.
Loss of consciousness.
GCS deterioration of 1 point (1 hour after presentation)
Age 40–60 years.  If there is ≥1 major criterion OR ≥2 minor criteria  present, then CT head is required.
Body System
Measured Factor High Impact
  • CT scan indicated

Result Interpretation

Ranges Ranges
  • Critical High: 1
  • Normal: 0
  • Normal Adult Male: 0
  • Normal Adult Female: 0
Result High Conditions
  • Head injury
Test Limitations
The prediction rule can only complement, never replace, clinical judgment and can therefore be used only as a decision-support system. If clinical suspicion is high, a CT scan is indicated regardless of the prediction.
References: 1


Study Validation 1
The Canadian CT Head Rule (CCHR) and New Orleans Criteria (NOC) are previously developed clinical decision rules to guide CT use for patients with minor head injury and with Glasgow Coma Scale (GCS) scores of 13 to 15 for the CCHR and a score of 15 for the NOC. However, uncertainty about the clinical performance of these rules exists. The aim of this study was to compare the clinical performance of these 2 decision rules for detecting the need for neurosurgical intervention and clinically important brain injury. A prospective cohort study (June 2000-December 2002) that included 9 emergency departments in large Canadian community and university hospitals, the CCHR was evaluated in a convenience sample of 2707 adults who presented to the emergency department with blunt head trauma resulting in witnessed loss of consciousness, disorientation, or definite amnesia and a GCS score of 13 to 15. The CCHR and NOC were compared in a subgroup of 1822 adults with minor head injury and GCS score of 15. The study concluded that For patients with minor head injury and GCS score of 15, the CCHR and the NOC have equivalent high sensitivities for need for neurosurgical intervention and clinically important brain injury, but the CCHR has higher specificity for important clinical outcomes than does the NOC, and its use may result in reduced imaging rates.
References: 2
Study Validation 2
This study compared the clinical performance of the Canadian CT Head Rule (CCHR) and the New Orleans Criteria (NOC) for detecting any traumatic intracranial lesion on computed tomography (CT) in patients with a Glasgow Coma Scale (GCS) score of 15. It also assessed the ability to detect patients with "clinically important" brain injury and patients requiring neurosurgical intervention. Additionally, the performance of the CCHR was assessed in a larger cohort of those presenting with GCS of 13 to 15. This prospective cohort study was conducted in a U.S. Level I trauma center and enrolled a consecutive sample of mildly head-injured adults who presented to the emergency department (ED) with witnessed loss of consciousness, disorientation or amnesia, and GCS 13 to 15. The rules were compared in the group of patients with GCS 15. The primary outcome was prediction of "any traumatic intracranial injury" on CT. Secondary outcomes included "clinically important brain injury" on CT and need for neurosurgical intervention. The findings of the study indicate that In a U.S. sample of mildly head-injured patients, the CCHR and the NOC had equivalently high sensitivities for detecting any traumatic intracranial lesion on CT, clinically important brain injury, and neurosurgical intervention, but the CCHR was more specific.
References: 3
Study Validation 3
An observational cohort study performed between 2008 and 2011 compared the performance of  New Orleans Criteria and Canadian CT Head both decision rules for identifying patients with intracranial traumatic lesions and those who require an urgent neurosurgical intervention after mild head injury. The clinical head CT scan findings and outcomes were collected prospectively . Primary outcome was needed for neurosurgical intervention, defined as either death or craniotomy, or the need of intubation within 15 days of the traumatic event. Secondary outcome was the presence of traumatic lesions on head CT scan. New Orleans Criteria and Canadian CT Head Rule decision rules were compared by using sensitivity specifications and positive and negative predictive value. The results of the study proved that for patients with mild head injury, the Canadian CT Head Rule had higher sensitivity than the New Orleans Criteria, with higher negative predictive value. The question of whether the use of the Canadian CT Head Rule would have a greater influence on head CT scan reduction requires confirmation in real clinical practice.
References: 4
Study Additional 1
The objective of the study was to compare the predictive performance of three previously derived cranial computed tomography (CT) rules, the Canadian CT Head Rule (CCHR), the New Orleans Criteria (NOC), and National Emergency X-Ray Utilization Study (NEXUS)-II, for detecting clinically important traumatic brain injury (TBI) and the need for neurosurgical intervention in patients with blunt head trauma. This was a prospective, multicenter, observational cohort study of patients with blunt head trauma from June 2008 to May 2009. The historical and physical examination components of the CCHR, NOC, and NEXUS-II were documented on a data collection form and the performance of each of the three rules was compared. Patient eligibility for each specific rule was defined exactly as previously described for each specific rule. To compare the three decision rules in terms of sensitivity and specificity, an intersection cohort satisfying inclusion criteria of all three decision rules was derived. The primary outcome was clinically important TBI, and the secondary outcome was neurosurgical intervention. The sensitivity and specificity of each rule were calculated with 95% confidence intervals (95% CIs).The study indicated that the three cranial CT decision rules had much lower sensitivities in this population than the original published studies, while the specificities were comparable to those studies. The sensitivities for neurosurgical intervention, however, were comparable to the original studies. The NEXUS-II rule showed the highest reduction rate for CT scans compared to other rules, but failed to identify all undergoing neurosurgical intervention for their original inclusion cohort.
References: 5
Study Additional 2
A  prospective observational study of the NEXUS Head CT DI in 4 hospital emergency departments was conducted between April 2006 and December 2015.  Prior work suggests that clinical criteria (National Emergency X-Radiography Utilization Study [NEXUS] Head CT decision instrument [DI]) can reliably identify patients with important injuries, while excluding injury, and the need for imaging in many patients. Validating this DI requires confirmation of the hypothesis that the lower 95% confidence limit for its sensitivity in detecting serious injury exceeds 99.0%. A secondary goal of the study was to complete an independent validation and comparison of the Canadian and NEXUS Head CT rules among the subgroup of patients meeting the inclusion and exclusion criteria. the study concluded that limitations of the study may arise from application of the rule by different clinicians in different environments. Clinicians may vary in their interpretation and application of the instrument's criteria and risk assignment and may also vary in deciding which patients require intervention. The instrument's specificity is also subject to spectrum bias and may change with variations in the proportion of "low-risk" patients seen in other centers.
References: 6
Study Additional 3
Reports have suggested that clinicians, when evaluating pediatric patients with blunt head trauma, may be over ordering head computed tomography (CT). Prior decision instruments (DIs) aimed at aiding clinicians in safely forgoing CTs may be paradoxically increasing CT utilization. This study evaluated a novel DI that aims for high sensitivity while also improving specificity over prior instruments. The study enrolled 1,018 patients less than 18 years old with blunt head injury and conducted a planned secondary analysis of the NEXUS Head CT DI among . The rule required patients satisfy seven criteria to achieve "low-risk" classification. Patients were assigned "high-risk" status if they fail to meet one or more criteria. The primary outcome was the ability of the rule to identify all patients requiring neurosurgical intervention. The study concluded that the Pediatric NEXUS Head CT DI reliably identifies blunt trauma patients who require head CT imaging and could significantly reduce the use of CT imaging.
References: 7


Marion Smits
Associate professor and neuroradiologist, Erasmus University Medical Center in Rotterdam, Netherlands
Research Interests: Applied physiological MR neuroimaging, focusing on the non-invasive, in vivo visualization of brain function


  1. Smits M, Dippel DW, de Haan GG, Dekker HM, Vos PE, Kool DR et al. External validation of the Canadian CT Head Rule and the New Orleans Criteria for CT scanning in patients with minor head injury. JAMA. 2005 Sep 28;294(12):1519-25.
  2. Stiell IG, Clement CM, Rowe BH, Schull MJ, Brison R, Cass D et al. Comparison of the Canadian CT Head Rule and the New Orleans Criteria in patients with minor head injury. JAMA. 2005 Sep 28;294(12):1511-8.
  3. Papa L, Stiell IG, Clement CM, Pawlowicz A, Wolfram A, Braga C, Draviam S, Wells GA. Performance of the Canadian CT Head Rule and the New Orleans Criteria for predicting any traumatic intracranial injury on computed tomography in a United States Level I trauma center. Acad Emerg Med. 2012 Jan;19(1):2-10.
  4. Bouida W1, Marghli S, Souissi S, Ksibi H, Methammem M, Haguiga H et al. Prediction value of the Canadian CT head rule and the New Orleans criteria for positive head CT scan and acute neurosurgical procedures in minor head trauma: a multicenter external validation study.Ann Emerg Med. 2013 May;61(5):521-7.
  5. Ro YS, Shin SD, Holmes JF, Song KJ, Park JO, Cho JS, et al. Comparison of clinical performance of cranial computed tomography rules in patients with minor head injury: a multicenter prospective study. Acad Emerg Med. 2011 Jun;18(6):597-604.
  6. Mower WR, Gupta M, Rodriguez R, Hendey GW. Validation of the sensitivity of the National Emergency X-Radiography Utilization Study (NEXUS) Head computed tomographic (CT) decision instrument for selective imaging of blunt head injury patients: An observational study. PLoS Med. 2017 July 11;14(7):e1002313.
  7. Gupta M, Mower WR, Rodriguez RM, Hendey GW. Validation of the Pediatric NEXUS II Head Computed Tomography Decision Instrument for Selective Imaging of Pediatric Patients with Blunt Head Trauma. Acad Emerg Med. 2018 Apr 17. doi: 10.1111/acem.13431. [Epub ahead of print]

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