Robust Data Validate PECARN Rules for Determining when CT Scans Can Be Avoided

July 29th, 2024

Applies to pediatric cases involving head trauma and intra-abdominal injury

By Dorothy Brooks

It has been more than a decade since a study from the National Cancer Institute raised alarm bells about the risks associated with radiation from computed tomography (CT) scans.¹ At the same time, however, no one can deny the huge value that a CT scan can provide to emergency clinicians who are racing to pin down what is causing a patient’s pain or distress. The question then becomes how to balance the benefits and risks when time is of the essence — as it often is in these cases.

A big part of the answer — at least for certain types of injuries in pediatric patients — is provided in a new, robust study that convincingly validates the Pediatric Emergency Care Applied Research Network (PECARN) rules outlining how to determine when CT scans are needed for young patients with traumatic brain injuries (TBI) and intra-abdominal injuries (IAI).²

The idea, of course, is to safely reduce unnecessary CT scans in children, particularly given the fact that the risks posed by the radiation from CTs is higher in pediatric patients, especially in the very young.³

The good news is that the three rules examined in this validation study — two rules for TBI and one rule for IAI — do an exemplary job of letting physicians know when a CT is warranted and when it is not. On this point, the data are quite clear. The prospective cohort study, which took place in six Level I Trauma Centers, found that out of 7,542 patients who were evaluated for abdominal trauma, the IAI rule had an accuracy rate of 100% (145/145) and a negative predictive value of 100% (3,488/3,488).

Similarly, the rules regarding TBI were applied to 19,999 children with head trauma enrolled in the study. In this case, the researchers found that the rule governing children younger than 2 years of age had an accuracy rate of 100% for patients requiring a CT scan (42/42) and a negative predictive value of 100% (2,940/2,940). Researchers found that the rule for children older than 2 years of age had an accuracy rate of 98.8% for patients requiring a CT scan (168/170) and a negative predictive value of 99.97% (6,015/6,017). Further, investigators report that neither of the two children with TBIs who were misclassified by the rule for children older than 2 years of age required neurosurgery or any other therapy beyond hospital observation.

Consider the evidence

The TBI and IAI rules have been available to clinicians for many years, according to the co-principal investigators who developed the rules for PECARN. Nathan Kuppermann, MD, MPH, the Bo Tomas Brofeldt Endowed Chair in the Department of Emergency Medicine at UC Davis Health, took the lead on developing the rules for TBI, which were published in 2009.4 Similarly, Kuppermann’s colleague, James Holmes, MD, MPH, the executive vice chair of Emergency Medicine at UC Davis Health, took the lead on developing the rule for IAI, which was first published in its current form in 2013.⁵

The researchers said that while major academic centers have gone a long way toward implementing the rules, particularly the rules for TBI, they are hoping that the size and scope of the new validation study will provide emergency medicine providers at smaller hospitals throughout the country with the confidence to put these rules into practice as well.

“The head injury rules have had a lot more uptake than the abdominal injury rules for a variety of reasons,” including the fact that the rules for TBI have been available for a longer period of time, notes Holmes. “Also, head trauma is a bit more common than abdominal trauma in the emergency department [ED], and I think people felt like there was a great need [for the TBI guidance] just based on how often they see [head trauma].”

However, Holmes anticipates that the new validation data will lead to greater adoption of the IAI rule as well. “We’ve already implemented some changes with our pediatric trauma surgeons [at UC Davis Health] on the initial evaluation of kids with abdominal trauma to basically put the PECARN abdominal rule into effect,” he says.

Leverage your EMR

What is involved with actually implementing the rules? “That means putting them into your electronic medical record [EMR] and doing active feedback; then inappropriate CT rates go down,” states Kuppermann. “If you don’t implement the rules in this way, then they slowly diffuse into the knowledge of clinicians, but much less rapidly than if you do active implementation.”

At UC Davis Health, CT rates for children with minor head trauma are also tracked by physicians, observes Kuppermann. “We can provide that evidence – and people are motivated to see whether they are practicing within the norms [of their peers],” he says. “Also, some [medical centers] actually provide direct feedback to physicians [on their practices regarding CT scans].”

These are some of the strategies hospitals and EDs can use to change clinician behavior so that it is in line with the PECARN rules, adds Kuppermann.

When the rules are embedded into the EMR, clinicians have immediate access to the risk factors in the rules that guide decision-making. For instance, Kuppermann explains while there are two distinct rules for head trauma – one for children younger than 2 years of age and one for older children -- three of the risk factors to be considered by the clinician are shared by both rules. These include altered mental status, any sign of a skull fracture on examination, and a history of loss of consciousness.

Kuppermann stresses that what is critically important is that if none of the risk factors are present, the risk of having a significant brain injury is extremely low, and the clinician should not order a CT scan. However, he adds that if a patient has one of the risk factors, it doesn’t mean that the patient is at high risk or that the patient requires a CT scan. “It just means that the patient is no longer in the lowest risk category,” he says. “A lot of children can be observed in the emergency department for a few hours if they have one of the risk factors or they have other things that need to be done.”

(See the algorithm for the TBI rule here: https://www.mdcalc.com/calc/589/pecarn-pediatric-head-injury-trauma-algorithm)

Similarly, the rule for IAI includes a number of risk factors to consider, although Holmes notes that clinicians should be particularly concerned if a patient’s level of alertness is low or if the child has abdominal tenderness on exam. “Once you have two, three or four [risk factors] the risk becomes so high that you probably need to get a CT scan, but the presence of just one variable does not necessarily mandate this step,” he says. (See the algorithm for the IAI rule here: https://www.mdcalc.com/calc/3971/pecarn-pediatric-intra-abdominal-injury-iai-algorithm)

Alert community providers

Community hospitals traditionally have been slower to adopt research of this nature, acknowledges Holmes. “Part of the problem with pediatric decision rules has to do with uncertainty with community physicians in providing care to children just because they don’t see injured children that often,” he says.

As a result, the places that tend to perform CT scans on children at higher rates tend to be community hospitals that don’t see a lot of kids, shares Holmes. “However, what these rules do is actually provide clinicians with the evidence to be confident that they can avoid getting a CT scan [in appropriate cases], and they aren’t going to miss something … even in cases where they may not be as comfortable because they just don’t see a lot of these sorts of injuries very often,” he says.

Kupperman observes that while evidence on pediatric care tends to be collected and validated in major academic medical centers, 90% of kids actually are seen in community hospitals, so getting the word out to providers in these care settings is a top priority. “We’re counting on dissemination [strategies through the PECARN network] and electronic medical records to help people do the right thing,” he says.

“It’s actually the rules that provide the kind of safety that clinicians are looking for,” adds Kuppermann. “Radiation [from CT scans] is a real issue, particularly in the youngest children and with respect to abdominal CT scans,” states Kuppermann. “There is a hefty dose of radiation that is associated with malignancy.”

The rules equip physicians with the guidance to avoid CT scans when they are not needed, and at the same time spare low-risk patients of needless exposure to radiation, states Kuppermann.

Holmes acknowledges that fear of litigation may prompt some clinicians to order CTs that are not necessarily warranted, but the rules should make a difference with this group. “I do think some of the testing that gets done in emergency departments is defensive testing, so hopefully these rules will provide the kind of evidence that physicians need [to conclude] they don’t have to worry about getting a CT scan when a child is negative [based on the PECARN rules],” he says.

More guidance

Kuppermann notes that a recently released study looks at the use of CTs in children who present to the ED with neck injuries.6 “We get a lot of CT scans of children’s necks, and we are overdoing it,” he says. To address the issue, researchers embarked on a 15-year study of 20,000 children who were at risk for a neck injury, and they’ve derived and validated guidance pertaining to when CTs scans are needed for this population, he explains.

There is also research underway looking at whether ultrasound is beneficial in children who present with blunt abdominal trauma. “It’s a randomized controlled trial where we’re going to enroll at least 3,200 patients, randomizing them to get a FAST [focused assessment with sonography in trauma] exam or not to get a fast exam, and then look at the rates of abdominal CT scans in those patients.”

Holmes believes that ultrasound probably provides some valuable additional information that may allow clinicians to avoid CT scans in some patients that are low risk, but still have a risk factor or two under the PECARN rule. “That study should be out in a couple of years, providing us with some additional information to help clinicians taking care of pediatric patients that are not necessarily PECARN [rule] negative,” he says.

In the meantime, though, both Holmes and Kuppermann stress that it is time for emergency providers to use the evidence-based rules they already have, including the rules pertaining to IAI and TBI. “While there is harm in missing things in medicine, such as injuries in children, there is also harm in over-testing such as, in this case, radiation-induced cancers,” states Kuppermann.

Consequently, Kuppermann urges clinicians not to just rely on their gestalt when engaging in clinical decision-making. “These rules are not meant to replace your judgment; they’re meant to empower your judgment so that when you go in to see a child you already have this evidence in the background,” he says. “You can make that empower your judgment.”

REFERENCES

1. Berrington de Gonsalez A, Mahesh M, Kim KP, et al. Projected cancer risks from computer tomographic scans performed in the United States in 2007. Arch Intern Med 2009;169:2071-2077.
2. Holmes JF, Yen K, Ugalde IT, et al. 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;8:339-347.
3. Pearce MS, Salotti JA, Little MP, et al. Radiation exposure from CT scans in childhood and subsequent risk of leukaemia and brain tumours: A retrospective cohort study. Lancet 2012;380:499-505.
4. Kuppermann N, Holmes JF, Dayan PS, et al. Identification of children at very low risk of clinically-important brain injuries after head trauma: A prospective cohort study. Lancet 2009;374:1160-1170.
5. Holmes JF, Lillis K, Monroe D, et al. Identifying children at very low risk of clinically important blunt abdominal injuries. Ann Emerg Med 2013;62:107-116.e2.
6. Leonard JC, Harding M, Cook LJ, et al. PECARN prediction rule for cervical spine imaging of children presenting to the emergency department with blunt trauma: A multicentre prospective observational study. Lancet Child Adolesc Health 2024;8:482-490.