An Umbrella Review of Systematic Review and Meta-Analysis Studies of Focused Assessment with Sonography for Trauma (FAST) Accuracy

Abstract

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Authors' contributions: 

This letter was written due to an invitation from the editorial board. SG, SP, JLSA, and PP conducted a literature review, and the manuscript was drafted and revised by SG, SP, JLSA, PP, UY, QG‎.

Acknowledgment:

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Full Text:

The advent of Focused assessment with sonography for trauma (FAST) scan over the past decade has ‎enabled physicians to be rapidly used in the context of vulnerable patients, especially those who are ‎difficult to transport in hemodynamics. Identification of free fluid inside the peritoneal cavity, ‎pericardium, and pleural spaces can be performed immediately upon admission to the hospital. Other ‎uses for FAST include diagnosing organ damage, pneumothorax, fractures, and as a triage tool. ‎However, radiologists are widely concerned about the use of ultrasound in trauma because there is ‎more trust in CT scans. Various articles on the use of FAST have been published for the initial ‎evaluation of patients with blunt abdominal trauma and many systematic review and meta-analysis ‎studies have been published. In this review, we aimed at reviewing the systematic review and meta-‎analysis about the FAST accuracy in blunt trauma. Eight meta-analysis studies were included in this ‎study. Despite significant advances in trauma management in the field of prehospital care, rapid transfer of ‎casualties, management of patient fluid therapy, and life-saving surgical techniques, the leading cause ‎of death in trauma remain hemorrhagic shocks. Free intra-abdominal fluids and findings suggesting ‎solid organ damages, pneumothorax, hemothorax, and hemoperitoneum following the abdominal ‎trauma, mostly getting first diagnosed by the FAST sonography before the computerized tomography ‎‎(CT) scan, could be enigmatic findings for medical decision making. With the presence of massive ‎amounts of free fluid within the abdomen, rapid deterioration of the patient's condition could be ‎inevitable leading to hemorrhagic shock within minutes to hours (1). Time-critical diagnosis, ‎treatment, and effective control of bleeding will save patients' lives and get them out of life-‎threatening situations. Successful and rapid clinical decision-making in stable patients with positive ‎findings in FAST sonography or unstable patients with negative FAST findings is a difficult and ‎complex process based on available scientific evidence, personal experience, and current rules and ‎regulations (2). Due to the explosive increase in clinical pieces of evidence on the application of ‎FAST sonography in blunt trauma, multiple systematic reviews have been published and there is a ‎need for conclusions to be drawn. A systematic review study is the answer to clinical questions based ‎on valid and up-to-date clinical evidence. Systematic review studies fill the gap between genuine ‎research studies and patient bedside decisions with the best up-to-date clinical evidence. ‎In this review, we critically evaluated these studies on the FAST sonography's place in the clinical ‎management of trauma.

Our literature review in PubMed and EMBASE with keywords of the ‎‎“Abdominal trauma”, “Systematic review”, “meta-analysis”, and “FAST sonography” was ‎accompanied‏ ‏with 8 studies from 2001 till 2020 (Table 1). Blunt abdominal trauma was assessed in 6 ‎studies and 2 studies evaluated penetrating abdominal trauma. Sensitivity-specificity pooling meta-‎analyses were performed for diagnostic accuracy of FAST in detecting solid organ lesions, free fluid ‎within the abdomen, pneumothorax, hemothorax, and hemoperitoneum. Two studies were on the ‎pediatric age group. In the case of the diagnostic test accuracy results, studies reported FAST ‎Sensitivity and Specificity in different conditions of blunt or penetrating abdominal trauma, pediatric ‎blunt trauma, and chest trauma.‎

Systematic reviews were assessed for publication bias and heterogenicity presence, where in most ‎cases publication bias was not fully assessed. As well as what we find in our review, Van et al. ‎showed that there is a struggle in systematic review and meta-analysis studies of diagnostic test ‎accuracy addressing publication bias assessment. These studies mostly rely on inadequate approaches ‎such as the Begg and Egger tests, which were not designed for diagnostic test accuracy meta-‎analyses. Van et al.’s analysis of the Begg, Egger, and Deek’s tests revealed that they produce distinct ‎findings and are hence incompatible. But they suggested Deeks' test to be used (3). The meta-analysis ‎studies we reviewed show that over time the number of articles included in the meta-analysis has ‎decreased. While in 2001, the meta-analysis study by Stengel et al. included 123 studies, more recent ‎studies in the last 5 years have all included less than 20 studies in their meta-analysis. Interpretation ‎of this issue is difficult given that there is no detailed publication bias in the studies.‎‏ ‏It seems that the ‎study field for FAST sonography is closing as researchers are working on newer methods and more ‎advanced modalities and some recent works are applicating FAST as a prognostic factor (12).  Studies showed that precise meta-analysis data pooling methods are needed as ‎in the case of the heterogenicity or various types of bias, results would extremely be different.‎

Table 1. studies included in our review