The PECARN study is the largest of the prospective evaluations of children with minor head injury for clinically important traumatic brain injury. The derived prediction instruments, for children aged <2 years of age and for children aged 2 to 18 years, generate “very low risk” cohorts whose incidence of important injury is negligible. However, the overall incidence of cTBI was quite low in the entire study – meaning each positive predictor still only raises the risk of cTBI from negligible to tiny.
One of the predictors, vomiting, is an element in the decision instrument for children aged 2 to 18 years. The management recommendation for patients with vomiting, then, defaults to “do as is your wont” – and studies suggest most folks are going ahead with CT, rather than using the “observation” option.
This study goes back and looks specifically at the vomiting component – and tries to tease out whether “isolated” or “non-isolated” prior to enrollment provided additional information. Of the 5,392 enrolled patients with complete data, 815 had a single episode of vomiting – with 0.2% having cTBI. The remaining 4,577 with non-isolated vomiting had a 2.5% incidence of cTBI. The article goes further into the details of the data set, noting patients with vomiting who received CT were more likely to have cTBI – but also had other concomitant comorbid injury.
This is, unfortunately, not terribly profound – and of debatable utility. The joy – what there is – of PECARN is its use as a decision-instrument with which to simplify medical decsion-making. Mining the details of individual +LR and -LR provides more patient-specific information, but increases the complexity of knowledge translation – and ultimately decreases the contextual acceptability of the product. The cTBI is heterogeneously distributed throughout the PECARN set – but the existing rule cannot be improved upon until better tools emerge to offload the cognitive demand required for for precision medicine-type applications.
“Association of Traumatic Brain Injuries With Vomiting in Children With Blunt Head Trauma”
http://www.ncbi.nlm.nih.gov/pubmed/24559605
Excellent comments Ryan.
Just big picture regarding the PECARN clinical decision instrument… I was originally most excited with such a large study giving us a quality "rule." But with my personal experience with it over the years I have become less impressed. I currently practice in Australia where there certainly is a cultural of performing less CT scans than in the USA. I find that if I follow the rule I would be getting more CT's and/or observing more kids than had I simply used my clinical gestalt. I find the rule quite helpful when it agrees with what I was going to do anyway and often will document in the chart "PECARN negative."
Going back to what Jerry Hoffman has been saying for years, perhaps it is time for a moratorium on clinical decision instruments for complex disease processes.
Brian
Brian Doyle, MD FACEP FACEM