Pecarn Head Injury Calculator

PECARN is a sequential algorithm, not an additive score, and runs in two age-specific versions because assessing an infant differs fundamentally from assessing a school-age child. For children under 2 the high-risk tier is a Glasgow Coma Scale below 15, altered mental status, or a palpable skull fracture; for children 2 and older, signs of basilar skull fracture replace palpable fracture. Either tier carries roughly 4.3 to 4.4 percent risk of clinically important traumatic brain injury and prompts CT. The intermediate tier under 2 comprises occipital, parietal or temporal scalp haematoma, loss of consciousness of 5 seconds or more, severe mechanism, or a parent reporting the child is not acting normally; over 2 it comprises any loss of consciousness, vomiting, severe mechanism, or severe headache. Intermediate risk sits near 0.8 to 0.9 percent, low enough that observation for 4 to 6 hours with serial examination is a defensible alternative to scanning. Severe mechanism includes motor vehicle ejection, rollover or crash fatality, being struck by a high-impact object, and a fall over 3 feet under 2 years or over 5 feet at 2 and above. Clinically important traumatic brain injury was defined narrowly and deliberately: death, neurosurgical intervention, intubation beyond 24 hours, or admission for two or more nights with CT findings. Isolated linear non-depressed skull fractures and brief observation stays do not count, since the aim was to avoid detecting abnormalities that require no action. Negative predictive value in the low-risk group exceeds 99.9 percent. The rule applies only to blunt trauma with GCS 14 or 15 and excludes penetrating injury, trivial mechanisms, ventricular shunts, brain tumours and bleeding disorders.

The Pediatric Emergency Care Applied Research Network was established in 2001 with funding from the Maternal and Child Health Bureau of the US Health Resources and Services Administration, created because paediatric emergency questions had historically been answered with adult data or single-centre series too small to settle anything. The head injury rule was PECARN's landmark output. Nathan Kuppermann of UC Davis led a prospective cohort of 42,412 children with minor blunt head trauma presenting to 25 network emergency departments between 2004 and 2006, with clinicians recording predictor variables on standardised forms before imaging decisions were made. The derivation and validation results were published in The Lancet in October 2009. The driver was radiation. CT use in paediatric head trauma had risen sharply through the 1990s and early 2000s, with institutional rates reported anywhere from about 15 to over 50 percent, while modelling work by David Brenner and others linked paediatric head CT to a small but real excess lifetime cancer risk on the order of one in several thousand. PECARN gave clinicians a validated way to withhold imaging rather than merely a way to justify it. External validation followed, including work by Lorton and colleagues in Academic Emergency Medicine in 2016, and the Australasian PREDICT network published a three-way comparison in 2017 of PECARN against the Canadian CATCH rule and the British CHALICE rule, finding PECARN the most sensitive. The rule now underpins paediatric head injury pathways across North America, Europe and Australasia.