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    CATCH (Canadian Assessment of Tomography for Childhood Head injury) Rule

    Predicts clinically significant head injuries in children.
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    INSTRUCTIONS

    Use in patients up to 16 yrs with minor head injury and initial GCS at least 13, injury within 24 hrs, plus at least one of the following: blunt trauma with witnessed LOC, amnesia, witnessed disorientation, vomiting 2+ times at least 15 mins apart, persistent irritability if under 2 years old. Do NOT use if: penetrating skull injury, depressed fx, focal neuro deficit, developmental delay, child abuse, re-eval after prior head injury, pregnant patient. Note: We recommend using PECARN, as it is more widely validated.

    When to Use
    Pearls/Pitfalls
    Why Use

    Pediatric patients up to 16 years old with minor head injury and:

    • Initial GCS ≥13 on physician determination,
    • Injury within 24 hours, AND
    • At least one of the following:
      • Blunt trauma to the head with witnessed loss of consciousness.
      • Definite amnesia.
      • Witnessed disorientation.
      • Vomiting two or more times at least 15 minutes apart.
      • Persistent irritability in a child under two years.

    Do not use in any of the following situations:

    • Penetrating skull injury.
    • Depressed fractures.
    • Acute focal neurological deficit.
    • Chronic generalized developmental delay.
    • Suspected child abuse.
    • Returning for re-evaluation after prior head injury.
    • Pregnant patients.
    • Identifies high risk patients with specific signs and symptoms.
    • Generalizability is limited, as it uses numerous strict inclusion and exclusion criteria.
    • Less sensitive than the PECARN Algorithm.
    • Original study included detailed sensitivity analysis for combinations of risk factors, perhaps giving a more nuanced approach to the decision to obtain CT.
    • Intoxicated patients were not excluded, making GCS estimation potentially unreliable.

    Original study included detailed sensitivity analysis for combinations of risk factors, perhaps giving a more nuanced approach to the decision to obtain CT.

    About the Creator
    Dr. Martin H. Osmond
    Content Contributors
    • Diana Fleisher, MD
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    Evidence
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    Advice

    • Patients who do not meet criteria for imaging should always be counseled about concussion and its symptoms and strict head injury return precautions (e.g. vomiting, somnolence, altered mental status).
    • Many still recommend a period of observation after head injury.

    Management

    Patients require CT if they have any of the high risk or medium risk factors. High risk predicts need for neurologic intervention; medium risk predicts brain injury on CT scan.

    Formula

    CT of the head is required only for children with minor head injury* and any one of the following findings:

    High risk (need for neurologic intervention)

    • GCS <15 at two hours after injury.
    • Suspected open or depressed skull fracture.
    • History of worsening headache.
    • Irritability on examination.

    Medium risk (brain injury on CT scan)

    • Any sign of basal skull fracture (e.g., hemotympanum, “raccoon” eyes, otorrhea or rhinorrhea of the cerebrospinal fluid, Battle’s sign).
    • Large, boggy hematoma of the scalp.
    • Dangerous mechanism of injury (e.g., motor vehicle collision, fall from ≥3 ft (91 cm) or 5 stairs, fall from bicycle with no helmet).

    *Minor head injury is defined as injury within the past 24 hours associated with witnessed loss of consciousness, definite amnesia, witnessed disorientation, persistent vomiting (more than one episode) or persistent irritability (in a child <2 years) with GCS 13–15.

    Evidence Appraisal

    Original study (Osmond 2012): 3,866 patients enrolled, age 0–16 years. Inclusion criteria were: Initial GCS ≥13 on physician determination, injury within 24 hours, and one of the following:

    • Blunt trauma to the head with witnessed loss of consciousness.
    • Definite amnesia.
    • Witnessed disorientation.
    • Vomiting two or more times at least 15 minutes apart.
    • Persistent irritability in a child under two years.

     Exclusion criteria were:

    • Penetrating skull injury.
    • Depressed fractures.
    • Acute focal neurological deficit.
    • Chronic generalized developmental delay.
    • Suspected child abuse.
    • Returning for re-evaluation after prior head injury.
    • Pregnant patients.

     Neurologic intervention was defined as any of the following occurring within seven days:

    • Death from head injury.
    • Craniotomy.
    • Elevation of skull fracture.
    • Monitoring of intracranial pressure.
    • Intubation for head injury. 

    Brain injury was defined as any acute intracranial finding on CT or pneumocephalus but excluding non-depressed skull fractures and basilar skull fractures. 

    Patients who did not receive CT scans initially were contacted 14 days later to assess for brain injury and recalled for CT scan if they denied all of the following: headache (unless mild), seizure or focal motor findings, and inability to return to usual daily activities.

    Drawbacks: Only 277 of 3,866 patients were under the age of two years. These patient are often considered as higher risk; however, the authors did not perform separate subgroup analysis. The rule missed three patients who did not require intervention: an occipital skull fracture with pneumocephalus, mild brain edema, and a small extra-axial hemorrhage with small cerebral contusion. Only 53% patients received a CT. Intoxicated patients were not excluded, making GCS estimation unreliable.

    Sensitivity and specificity of risk factors in relation to need for neurologic intervention:

    • ≥1 of the four high risk factors: 100% sensitive (95% CI 86.2–100), 70.2% specific (95% CI 68.8–71.6%).

    Sensitivity and specificity of high and medium risk factors to presence of brain injury on CT:

    • ≥1 of the four high risk factors OR three of the medium risk factors:  98.1% sensitive (95% CI 94.6–99.4%), 50.1% specific (95% CI 48.5–51.7%). 51.9% of patients would be scanned.
    • ≥1 of all seven factors: 98.1% sensitive (95% CI 98.0–50.1%).

     Lyttle 2013: This study showed that CATCH identifies high risk patients with specific signs and symptoms, CHALICE identifies broad groups of high risk patients, and PECARN identifies risk patients. Given that CATCH, CHALICE and PECARN aim to identify patients at different levels of risk, 949 patients were evaluated to determine the proportion of patients with head injury to which clinical decision rule (CDR) applied. No CDR was applicable to all patients. CHALICE was the most applicable, 95% (95% CI 96–98%) and CATCH was the least applicable, 26% (95% CI 24–29%).

    Lyttle 2012: In a systematic review and assessment of CATCH with the Quality Assessment of Diagnostic Accuracy Studies Tool, the authors noted that CATCH was distinctive from CHALICE and PECARN for several reasons: CATCH was the only CDR to perform with 100% sensitivity  identifying the primary outcome, it defined intracranial findings on CT as a secondary (not primary) outcome and did not include hospital admission as an outcome unlike the other CDRs, and it collected the fewest predictor variables in its derivation (26 compared to CHALICE and PECARN’s 40 and 36, respectively). Kappa values for assessment of clinical variables for all three studies were >0.5. CATCH’s derivation was unique in the use of bootstrapping to evaluate the alternative combinations of risk factors, though all three CDRs used recursive partitioning in multivariate analysis.

    Easter 2014: This single center prospective observational study compared physician estimation (gestalt prediction of <1% risk of TBI) and practice (actual CT ordering practice) with CATCH, CHALICE and PECARN clinical decision rules on children under 18 with GCS ≥13 presenting within 24 hours of blunt head injury. PECARN’s definition of clinically important TBI (ciTBI) was the primary outcome. Sensitivities and specificities were as follows:

    • PECARN: 100% sensitive (95% CI 84–100), 62% specific (95% CI 59–66).
    • Physician practice: 100% sensitive (95% CI 84–100), 50% specific (95% CI 47–53).
    • Physician estimation: 95% sensitive (95% CI  76–100), 68% specific (95% CI 65–71).
    • CATCH: 91% sensitive (95% CI 70–99), 44% specific (95% CI 41–47).
    • CHALICE: 84% sensitive (95% CI 60–97), 85% specific (95% CI 82–87).

    While not an external validation study per se, the authors demonstrated that PECARN and physician practice identified all ciTBIs.

    Literature

    Dr. Martin H. Osmond

    About the Creator

    Martin H. Osmond, MD, is a pediatric emergency physician at the Children’s Hospital of Eastern Ontario (CHEO). He is also the CEO and scientific director of the CHEO Research Institute. Dr. Osmond’s areas of research interest are the evaluation and management of pediatric head injuries and the use of pre-hospital care in the treatment of ill and injured children.

    To view Dr. Martin H. Osmond's publications, visit PubMed

    Content Contributors
    • Diana Fleisher, MD