Effect of crew ratio of advanced life support-trained personnel on patients with out-of-hospital cardiac arrest: A systematic review and

Background/purpose: This review aimed to investigate the effect of crew ratios of on-scene advanced life support (ALS)-trained personnel on patients with out-of-hospital cardiac arrest (OHCA). Methods: We systematically searched PubMed, Ovid EMBASE, and the Cochrane Central Register of Controlled Trials databases from the inception date until September 30, 2022, for eligible studies. Two reviewers independently screened the studies for relevance, extracted data, and quality. We compared the effect of the ratio of on-scene ALS-trained personnel >50 % to those with a ratio <50 % among prehospital personnel on the clinical outcomes of OHCA patients. The primary outcome was survival-to-discharge and secondary outcomes were any return of spontaneous circulation (ROSC), sustained ROSC (>2 h), and favourable neurological outcome at discharge (cerebral performance category scores: 1 or 2). Pooled odds ratios (ORs) were calculated, and the certainty of evidence was assessed. Results: From 10,864 references, we identified four non -randomised studies, including 16,475 patients. Two studies were performed in Japan and two in Taiwan. There were significant differences in survival -to -discharge (OR: 1.24, 95 % confidence interval [CI]: 1.07-1.44, I-2 : 7 %), any ROSC (OR:1.22, 95 % CI: 1.04-1.43, I-2 : 74 %) and sustained ROSC (OR: 1.39, 95 % CI: 1.16 -1.65, I-2 : 40 %), but insignificant differences in favourable neurological outcome at discharge. The overall certainty of evidence was rated as very low for all outcomes. Conclusion: Prehospital ALS care with a ratio of on -scene ALS-trained personnel >50 % could improve OHCA patient outcomes than crew ratios <50 %. Further studies are required to reach a robust conclusion.