When is it safe to forego a CT

in kids with head trauma?

(based on the article: Identification of children at very low risk of clinically-important brain injuries after head

trauma: a prospective cohort study)

Beverly Wilson

Journal Club

January 31, 2011

A review of the literature using PP-ICONS

Why don’t we image all pediatric patients with head injuries?

Diagnostic radiation poses a risk to children 1/1000 to 1/5000 head scans results in a lethal

malignancyRisk increases as age decreases

One CT head radiation exposure is approximately equal to 8 months of environmental background radiation

A child’s overall lifetime risk of cancer death = 20-25%Estimated increased risk of CA from a single

CT is estimated to be .03-.05% (may be cumulative)

Accurate, generalisable prediction rules for identifying children at very low risk of ciTBI are needed to avoid over exposure to radiation.

Pediatric head trauma causes: 7200 deaths annually60,000 hospitalizations annually > 600,000 ED visits a year

More than half of kids brought to ED for head trauma undergo CT head

CT use doubled between 1995-2005

To CT or not to CT children with GCS of 14 or 15 after

sustaining head trauma

North American pediatric patients (age 0-18) with a GCS of 14 or 15 who present for care within 24 hours of sustaining head trauma.

(definitely relevant to our patient population)

Prospective Cohort Study25 ED’s in North America42,412 children

Children with low impact trauma were excluded Children with known brain tumor, penetrating

trauma, preexisting neuro disorder are excluded.

2 Age Groups: Preverbal and VerbalObtained CT head for 14,969

1) altered mental status (gcs<15) Somnolence, slow response to verbal

communication

2) palpable skull fracture 3) loss of consciousness for > 5s 4) Nonfrontal Scalp Hematoma 5) Severe mechanism of injury 6) acting abnormally according to

parent

1) Altered Mental Status (gcs<15) Somnolence, repetitive Q’s, slow response to

verbal communication

2) Severe mechanism of injury 3) Clinical signs of basilar fracture 4) Any LOC 5) Hx of Emesis 6) Severe headache

Tested against the old clinical prediction rules that existed

“Many of the predictors identified in our rules have been studied previously with conflicting results, and variables identified as predictors of traumatic brain injuries in some studies were not predictive in others.

These conflicting results are partly attributable to insufficiently large sample sizes to produce precise risk estimates. Additionally, the lack of validation studies compromises the generalisability of previous rules”

For children < 2 yrs: All six clinical predictors neg = 100% negative predictive value and 100% sensitivity

For children 2yrs and older: All six clinical predictors neg = 99.95% neg predictive value and 96.8% sensitivity

ie: very high negative predictive value for identifying children without ciTBIs for whom CT scans could be omitted

Among all children enrolled, those with none of the six variables in the rules for whom CT scans could routinely be avoided accounted for 25% of CTs in those younger than 2 years and 20% of CTs in those aged 2 years and older.

Power: The study is very large, allowing

sufficient statistical power to generate robust and generalisable rules. (42,412 children)

Accuracy: Their accuracy was confirmed by

validation populations.

Negative Predictive Value = the probability that the patient will not have the disease when restricted to all patients who test negative. NPV = TN / (TN + FN)

1176/1176 for < 2yo 3798/3800 for 2yo-18yo

Sensitivity = measures the proportion of actual positives which are correctly identified as such (e.g. the percentage of sick people who are correctly identified as having the condition). Sensitivity = True Positives/True Positives + False

Negatives 25/25 for < 2yo 61/63 for 2yo-18yo

1) The Emergency Medical Services for Children Programme of the Maternal and Child Health Bureau

2) Maternal and Child Health Bureau Research Programme

3) Health Resources and Services Administration

4) US Department of Health and Human Services.

Role of the funding source The sponsors had no role in study design, study

conduct, data collection, data interpretation, and report preparation. The corresponding author has access to all data and had final responsibility for the decision to submit for publication.