Establishing the S tandardized E MS M etrics for S urvival in T ransfusion and A dvanced R esuscitation: the SEMSTAR project

Background Prehospital blood transfusion is increasingly recognized as an important early resuscitation intervention for patients with hemorrhagic shock. However, comprehensive evaluations of such programs have been limited by heterogeneity in data collection, outcome definitions, and reporting methodologies. This impedes effective benchmarking, quality improvement initiatives, research efforts, and the creation of protocols and policies. The Standardized Emergency Medical Service (EMS) Metrics for Survival in Transfusion and Advanced Resuscitation (SEMSTAR) project sought to develop consensus-driven data elements and standardized outcome definitions to facilitate consistent reporting of prehospital blood transfusion programs. Methods Initial data metrics were identified through a literature review and surveyed across US EMS systems that perform prehospital transfusions. A modified Delphi methodology was then used by a multidisciplinary panel of 28 subject-matter experts in EMS, trauma surgery, transfusion medicine, and resuscitation science. Predefined thresholds analyzed metric inclusion, classification as either core or expanded elements, and endorsement of standardized outcome definitions. Results 89 EMS systems completed the initial survey of 208 potential data elements. Of these, 193 (93%) advanced to expert review. Experts reached consensus on 168 data elements: 86 core metrics for universal reporting and 82 expanded metrics for comprehensive analysis. Consensus was also achieved on standardized definitions for hemorrhagic circulatory collapse, including stratification by pretransfusion circulatory collapse status and survival after prehospital transfusion. Wherever possible, the resulting framework draws from existing data infrastructure, including the National Emergency Medical Services Information System and trauma registry variables. Conclusion SEMSTAR establishes the first national, consensus-driven framework for standardized data collection and outcome reporting among prehospital blood transfusion programs. By defining core and expanded metrics with standardized survival definitions, this framework enables benchmarking, quality improvement, and multicenter research across diverse EMS systems. SEMSTAR adoption will enable rigorous program evaluation and support the development of a national registry to advance evidence-based care for patients with hemorrhagic shock. Level of evidence IV