Evidence base for point-of-care ultrasound (POCUS) for diagnosis of skull fractures in children: a systematic review and meta-analysis

Background Blunt head trauma is a common presentation to emergency departments (EDs). Identifying skull fractures in children is important as they are known factor of risk for traumatic brain injury (TBI). Currently, CT is the reference standard for diagnosing skull fractures and TBIs in children. Identifying skull fractures with point-of-care ultrasound (POCUS) may help risk-stratify children for TBI following blunt trauma. The purpose of this study is to evaluate the sensitivity, specificity, positive predictive value and negative predictive value of POCUS in identifying skull fractures in children. Methods A systematic search was performed on 17 July 2020 in Ovid Medline, Cochrane Library, Google Scholar, Web of Science and Embase. Prospective studies reporting skull fractures diagnosed with ultrasound in children younger than 18 years due to blunt head injury were included. Studies that did not confirm the fracture with CT were excluded. The quality of studies was evaluated using the QUADAS-2 tool. Data were extracted from the eligible studies to calculate outcomes such as sensitivity and specificity; when possible overall outcomes were calculated. Results Seven studies were included. All eligible studies included patients for whom the decision to perform a CT scan was made in advance. Overall, the included studies demonstrated low risk of bias or had minor concerns regarding risk of bias. The pooled data (n=925) demonstrated a sensitivity of 91%, specificity of 96%, positive predictive value of 88% and negative predictive value of 97%. Conclusion The included studies demonstrate minor methodological limitations. Overall, the evidence suggests that POCUS is a valid option for diagnosing skull fractures in children visiting the ED after blunt head injury.


Introduction
Blunt head trauma is a common presentation to emergency departments (ED). Identifying skull fractures in children is important as they are a known risk factor for traumatic brain injury (TBI). [2][3][4][5][6][7][8] Currently, computer tomography (CT) scan is the reference standard for diagnosing skull fractures and TBIs in children. However, CT scans expose children to radiation that may increase lifetime risk of lethal malignancy [9][10][11][12] . Identifying skull fractures with point-of-care ultrasound (POCUS) may help riskstratify children for TBI following non-penetrating trauma. The purpose of this study is to evaluate the sensitivity, specificity, negative predictive value and positive predictive value of POCUS in identifying skull fractures in children.

Objective
What is the sensitivity, specificity, negative predictive value and positive predictive value of POCUS in identifying skull fractures in children that present with blunt head injury in the emergency department?

Methods
The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline shall be used to conduct this review. 13 Prior to conducting this review consensus shall be reached among all authors on search syntax, criteria of inclusion and exclusion, and the criteria for the assessment of validity and relevance in the identified articles Eligibility criteria -Children aged <18 years with blunt head injury visiting the emergency department -Ultrasound and CT used as means to diagnose skull fracture -Prospective study -Articles in English, German, French or Dutch

Information sources
The search will be conducted in the search engines Ovid Medline, Cochrane Library, Google Scholar, Web of Science and Embase. Only the first hundred results in Google Scholar will be used for the selection process.

Search strategy
The search syntax encompasses 'skull', 'ultrasound', and 'fracture' (including their respective synonyms). See Table 1 for complete search syntax. Data will be managed using EndNote X9, Clarivate Analytics, Philadelphia, USA.

Selection process
Our aim is to include all prospective studies written in English, German, French or Dutch that assessed children with blunt head injury and visited the emergency department for this. Firstly, all duplicates shall be excluded. Based on the inclusion criteria two reviewers (GA and EV) screen the titles and abstracts of the articles. We shall exclude articles that are reviews, conference abstracts or case reports. The full text of the remaining articles will be screened by two reviewers (EV and GA). From these articles and the identified reviews, all references shall be screened utilizing the same criteria.

Data collection process
Two authors shall extract data separately from the eligible studies (EV and GA).

Data items
The following data shall be extracted: year of publication, study characteristics, baseline population characteristics and data on the outcomes.

Risk of bias in individual studies
The quality of the individual studies shall be evaluated utilizing QUADAS-2. 14 Three authors (GA, EV and AR) will independently evaluate the quality of the eligible studies. The aim is to reach consensus among the critical appraisers through discussion.

Data Synthesis
Data will be presented in tabulated form to allow for semi qualitative comparison of; study sample, population characteristics, training and experience of physicians, trauma mechanism and incidence of fractures. Preferably the sensitivity, specificity, negative predictive value and positive predictive value will be reported; moreover, the false positive and false negatives cases will be reported.

Meta-analysis
If possible, the data of the studies will be pooled to calculate overall outcomes. The homogeneity of the studies will be determined with visual inspection; we shall analyze the homogeneity in age and trauma mechanism.

Meta-biases
To identify possible 'gray literature' we shall include a computerized search in Google Scholar.   Web of science TS=(((skull OR cranium OR cranial OR calvarium OR scalp OR skullcap OR head)) AND ((echogra* OR ultraso* OR sonogra* OR pocus)) AND ((fracture*)) AND ((child* OR infan* OR adolescen* OR pediatr* OR paediatr*))) Google Scholar skull|cranium|cranial|calvarium|scalp|skullcap|head echogram|echography|ultrasonography|ultrasound|sonogram fracture child| children|infant|adolescent|pediatric|paediatric|infants|adolescents|pediatrics|paediatrics BMJ Publishing Group Limited (BMJ) disclaims all liability and responsibility arising from any reliance Supplemental material placed on this supplemental material which has been supplied by the author(s)