Clinical Learning-Curve Evidence and Experience-Related Temporal Trends of Resuscitative Endovascular Balloon Occlusion of the Aorta in Patients with Trauma: A Systematic Review.

Background/Objectives: Resuscitative endovascular balloon occlusion of the aorta (REBOA) is a technically demanding, low-frequency intervention that requires both operator proficiency and coordinated trauma-system performance. We systematically reviewed direct clinical evidence on REBOA learning curves and indirect experience-related temporal trends. Methods: PubMed/MEDLINE, Embase, and the Cochrane Library were searched through 24 April 2026. The prespecified primary outcomes were procedural efficiency and safety; mortality and survival were secondary outcomes. The review protocol was prospectively registered in PROSPERO (CRD420261357432). Because of substantial clinical and methodological heterogeneity, quantitative pooling was not performed, and the evidence was synthesized narratively. Studies were classified as direct case-based learning-curve analyses using sequential case numbers or cumulative procedural volume, or as indirect temporal-trend analyses using calendar year or successive study periods as proxies for institutional or system-level experience. Results: Seven observational studies were included. Three studies provided direct case-based learning-curve evidence using sequential case numbers, whereas four registry-based studies evaluated calendar-time trends as indirect proxies for institutional or system-level experience. The three direct studies identified study-specific inflection points at different case numbers, including approximately 5 and 10 cases for individual- and institutional-level technical challenges and 5, 17, and 34 cases for risk-adjusted mortality across three of five centers; improvement was not consistently observed across all centers. In contrast, the four temporal-trend studies generally reported improved outcomes over time but did not identify case-volume thresholds and could not isolate the effect of accumulated experience from concurrent changes in trauma care. Conclusions: Direct clinical evidence on the REBOA learning curve remains limited to a small number of case-based studies. Calendar-time trends may reflect broader institutional or system-level maturation but cannot independently establish a learning-curve effect. By providing an integrated clinical perspective on how REBOA proficiency may develop in real-world practice, this review highlights the need for prospective studies using standardized procedural outcomes and risk-adjusted learning-curve methods.