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PECARN Head and Abdomen Rules…Validated!

May 24, 2024

Written by Jason Lesnick

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This multicenter prospective validation study of the PECARN prediction rules for CT imaging of children with blunt abdominal or minor head trauma performed extremely well (both having NPVs of 100%).

Yes, you PECARN avoid that CT
This was a multicenter prospective validation study involving 6 different level 1 Pediatric EDs in Texas and California from 12/27/16 to 9/1/21 in patients < 18 years old. Patients were enrolled into an abdominal trauma cohort (7,542 children, median age 9.7) or a minor head injury cohort (19,999 children) that was segregated by age less than 2 years old (5,647 children, median age 0.9) vs. older than 2 years (14,352 children, median age 8.2). The usual exclusion citeria applied*. CT imaging was obtained at attending clinician discretion.

All enrolled children were evaluated using the variables of the relevant PECARN prediction rule before CT results were reviewed. The primary outcome in the abdominal trauma cohort was intra-abdominal injury requiring acute intervention (therapeutic laparotomy, angiographic embolization, blood transfusion, IVF for ≥2 days for pancreatic or gastrointestinal injuries, or death from intra-abdominal injury). The primary outcome in the age-segregated minor head trauma cohorts was clinically important TBI (neurosurgery, intubation for >24 h for TBI, or hospital admission ≥2 nights for ongoing symptoms and CT-confirmed TBI; or death from TBI).

The authors found the intra-abdominal injury rule had a sensitivity of 100% (95%CI 98.0–100.0; 145/145) and a NPV of 100% (95%CI 99.9–100.0; 3488/3488). The TBI rule for children younger than 2 years had a sensitivity of 100.0% (93.1–100.0; 42/42) for clinically important traumatic brain injuries and a NPV of 100%; 99.9–100.0; 2940/2940), whereas the traumatic brain injury rule for children aged 2 years and older had a sensitivity of 98.8% (95.8–99.9; 168 of 170) and a NPV of 100.0% (99.9–100.0; 6015/6017). Notably, the two children who were misclassified by the TBI rule were admitted to hospital for observation for > 2 nights but did not need neurosurgery.

How will this change my practice?
First off, thank goodness for the PECARN group. We have covered the PECARN TBI prediction rule previously for how well it works but this is the first prospective validation of the PECARN intra-abdominal injury prediction rule. The authors in my opinion appropriately conclude that these rules should be implemented in widespread fashion to decrease unnecessary CT use in children. I will continue to use the PECARN TBI rule and will now be implementing the PECARN intra-abdominal injury rule as well.

*Patients were excluded if they were pregnant or had pre-existing neurological disorders preventing examination, penetrating trauma, injuries more than 24 h before arrival, CT or MRI before transfer, or high suspicion of non-accidental trauma.

Editor’s Notes:

Nick Zelt:
Though it may have secured them the Lancet publication, I think these authors bit off more than they could chew by deciding to report the validation of both prediction tools in the same article. As a result, I didn’t feel they included enough detail to convince me that these tools are reducing unnecessary CT scans. Though they certainly seem safe.

Clay Smith:
There are several things here:

  1. These rules are most helpful when negative. PECARN-positive does not mean we should reflexively order CT. Such a practice would increase scanning. Some PECARN-positive kids do need a CT; some just need observation.
  2. The criteria are nuanced. For example, severe HA is a risk factor in kids >2 years but is defined as 8-10 out of 10. MDCalc doesn’t say 8/10; it just says “severe,” which is why it’s good to read the original articles.
  3. 42 solid organ injuries were not identified by the IAI prediction rule and were not counted in the primary outcome, because there was no intervention performed. Does a grade 3 liver laceration matter? It certainly could! So, the rule is not perfect in finding all injuries, but it’s awfully good at finding the ones that matter.
  4. We call them decision “rules.” But your clinical assessment and judgment is the final rule. By all means, use PECARN. I certainly do. I’ve had hundreds of conversations with families about the pros and cons of imaging using the PECARN rule. Most of the time I follow PECARN and persuade families to come along with me, but sometimes there are exceptions to the “rules” that you have to judge at the bedside.

PECARN prediction rules for CT imaging of children presenting to the emergency department with blunt abdominal or minor head trauma: a multicentre prospective validation study. Lancet Child Adolesc Health. 2024 May;8(5):339-347. doi: 10.1016/S2352-4642(24)00029-4. PMID: 38609287.

What are your thoughts?