The Next PECARN Rule? - NEXUS II CT Rule for Kids

Written by Clay Smith

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The NEXUS II Pediatric Head CT Decision Instrument was 100% sensitive for ruling out children with a neurosurgical outcome, but it was relatively small and had wide confidence intervals.  I don't think this will supplant PECARN.

Why does this matter?
The PECARN rule is most often used in practice when evaluating whether or not children need a head CT following head trauma.  But some studies have raised concern that PECARN may be no better than physician judgment and may actually increase CT use.  What if we used a "physician judgment first - decision instrument next" approach?  Enter the NEXUS II for kids.

Better than PECARN?
This was a multicenter prospective evaluation of the NEXUS II head CT criteria, only in children under 18.  The NEXUS head CT criteria were specifically designed for patients whom the clinician did not think were low risk and were considering CT. Clinicians had to complete a form and record the criteria prior to imaging, unless unstable.  CT ordering was per physician discretion.  This decision instrument was only to be used for children in whom imaging was being considered, a "judgment first - decision instrument next approach."

The 7 criteria were:

  1. No evidence of skull fracture
  2. No scalp hematoma
  3. No neurological deficits
  4. Normal level of alertness
  5. Normal behavior
  6. No persistent vomiting
  7. No coagulopathy

In about 1000 children, these criteria were 100% sensitive, 33% specific for neurosurgical intervention, but the 95% CI was wide, 87-100%.  They were 98% sensitive, 34% specific for the secondary outcome - clinically significant injury on CT.

This is promising, but it doesn't seem to add much to PECARN.  Most of the criteria are identical to, or slight variations from PECARN. Also, with only 27 patients having a neurosurgical outcome and wide 95% CI, I don't feel good about putting this study into practice.  PECARN dwarfs it in size, with over 42,000 patients compared to about 1000 in this study.

Source
Validation of the Pediatric NEXUS II Head CT 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]

Peer reviewed by Thomas Davis

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