Blunt head trauma is a common cause of death and disability in children worldwide and accounts for approximately 52,000 deaths and 275,000 hospital admissions in the United States annually . Each year more than 650,000 children visit emergency departments (EDs) in the United States with apparently minor blunt head trauma (Glasgow Coma Scale (GCS) scores of 14 to 15) .
A cranial computed tomography (CT) scan, the reference standard test for the emergent diagnosis of traumatic brain injury (TBI) in children with blunt head trauma, exposes children to ionizing radiation which has been linked to the development of brain tumors, leukemia, and other cancers [3, 4]. Furthermore, although radiation exposure from a single head CT scan may not significantly increase an individual’s risk of cancer, patients often undergo multiple CT examinations over their lifetime and the cumulative radiation dose may exceed the 50 mSv  threshold that has been linked to the development of cancer among atomic bomb survivors .
One method to reduce CT use in patients with blunt head trauma is through evidence-based clinical prediction rules . In 2009, Kuppermann et al. derived and validated two clinical prediction rules to accurately identify children at very low risk for clinically-important TBIs (ciTBIs) . The rules were developed from a cohort of more than 42,000 children with minor blunt head trauma among 25 EDs in the United States. They have been externally validated  and are accurate for use in clinical practice . Two rules were created, one for children younger than 2 years and a second for children between 2 and 18-years-old. The rules and study data allow for the classification of children into three risk groups: high risk, for whom a CT scan is recommended (risk of ciTBI for the younger than 2 and 2 to 18-years-old age groups is 4.4% and 4.3%, respectively); moderate risk, for whom observation or a CT scan are reasonable options depending on parental preference, clinician experience, and other factors (risk of ciTBI for the younger than 2 and 2 to 18-years-old age groups is 0.9% and 0.8%, respectively); and low risk, for whom a CT scan is typically not recommended (risk of ciTBI for the younger than 2 and 2 to 18-years-old age groups is <0.02% and <0.05%, respectively) . Although the prediction rules recommend observation or a CT scan as reasonable options for children in the moderate risk group, the rules provide little guidance for clinicians regarding how to weigh each of these factors and engage parents in the decision-making process.
Shared decision-making (SDM) is a process of decision-making in medicine that has several key features: the involvement of the patient (or parent, in a child’s case) and the clinician, a sharing of information by both parties, and both parties taking steps to reach an agreement about which management option to implement . While SDM may occur in a routine discussion during a clinical encounter, clinical decision-support tools may be necessary to effectively present comparative effectiveness research findings in a way that facilitates SDM. Decision aids provide the best scientific evidence available to support decision-making, prompt clarification of patient values and preferences, and have become increasingly used to provide the necessary decision support for SDM .
To facilitate SDM between clinicians and parents of children with minor head trauma at low-moderate risk for ciTBI, we sought to develop and test a decision aid, ‘Head CT Choice’. Specifically, we aimed to incorporate risk estimates for ciTBI from the Pediatric Emergency Care Applied Research Network (PECARN) prediction rules, along with the perspectives of parents and other stakeholders, in an iterative development process to produce a decision aid that is ready for testing. We hypothesized that use of the decision aid will significantly increase parents’ knowledge and satisfaction and safely tailor the rate of cranial CT scan and seven-day healthcare utilization to risk-informed parent preferences. In this manuscript, we describe the methods and protocol used to develop and refine the Head CT Choice decision aid and how we will test its effectiveness in a multicenter randomized trial.