Accuracy of risk tools to predict critical bleeding in major trauma: a systematic review with meta-analysis

Background: Early detection of critical bleeding by accurate tools can help ensure rapid delivery of blood products to improve outcomes in major trauma patients. We conducted a systematic review to evaluate the accuracy of risk tools to predict critical bleeding in patients with major trauma. Methods: PubMed, Embase and CENTRAL were searched up to February 2021 for studies investigating risk tools to predict critical bleeding for major trauma people in pre-hospital and emergency department. We followed the PRISMA-DTA guidelines. Two independent authors included studies, extracted data, appraised the quality using the Quality Assessment of Diagnostic Accuracy Studies-2 and assessed the certainty of evidence using thee Grading of Recommendations Assessment, Development and Evaluation methodology. Sensitivity, specificity and the Receiver Operating Characteristics curve for all selected triage tools. Results: Eighty-nine observational studies for adults and 12 observational studies for children met our inclusion criteria. In adults, we found 23 externally validated and 28 un-validated tools; in children, 3 externally validated tools and 5 un-validated. In the externally validated tools, we identified those including clinical, laboratory and ultrasound assessments. Among tools including only a clinical assessment, the Shock Index showed high sensitivity and specificity with the Certainty of Evidence ranging from very low to moderate in adults, as well as Shock Index Pediatric Age-adjusted (SIPA) with a moderate Certainty of Evidence. We found that tools using clinical, laboratory and ultrasound assessments were overall more accurate than those tools without all three components. Conclusions: Clinicians should consider risk tools to predict critical bleeding in a time-sensitive setting like major life threatening trauma. The Shock index and SIPA are easy and handy tools to predict critical bleeding in the pre-hospital setting. In the emergency department, however, many other tools can be utilized which include laboratory and ultrasound assessments, depending on staff experience and resources. Level of evidence: Systematic review, diagnostic Level III.