Abstract: We found two completed studies involving a total of 1136 participants that ultimately met our inclusion criteria. We also found one ongoing study and one planned study. We noted significant heterogeneity in the characteristics of interventions and outcomes measured or reported across these studies, thus we could not pool study results. One completed study considered the dispatch of police and fire service CFRs equipped with automatic external defibrillators (AEDs) in an EMS system in Amsterdam and surrounding areas. This study was an RCT with allocation made by cluster according to non-overlapping geographical regions. It was conducted between 5 January 2000 and 5 January 2002. All participants were 18 years of age or older and had experienced witnessed OHCA. The study found no difference in survival at hospital discharge (odds ratio (OR) 1.3, 95% confidence interval (CI) 0.8 to 2.2; 1 RCT; 469 participants; low-certainty evidence), despite the observation that all 72 incidences of defibrillation performed before EMS arrival occurred in the intervention group (OR and 95% CI - not applicable; 1 RCT; 469 participants; moderate-certainty evidence). This study reported increased survival to hospital admission in the intervention group (OR 1.5, 95% CI 1.1 to 2.0; 1 RCT; 469 participants; moderate-certainty evidence). The second completed study considered the dispatch of nearby lay volunteers in Stockholm, Sweden, who were trained to perform cardiopulmonary resuscitation (CPR). This represented a supplementary CFR intervention in an EMS system where police and fire services were already routinely dispatched to OHCA in addition to EMS ambulances. This study, an RCT, included both witnessed and unwitnessed OHCA and was conducted between 1 April 2012 and 1 December 2013. Participants included adults and children eight years of age and older. Researchers found no difference in 30-day survival (OR 1.34, 95% CI 0.79 to 2.29; 1 RCT; 612 participants; low-certainty evidence), despite a significant increase in CPR performed before EMS arrival (OR 1.49, 95% CI 1.09 to 2.03; 1 RCT; 665 participants; moderate-certainty evidence). Neither of the included completed studies considered neurological function at hospital discharge or at 30 days, measured by cerebral performance category or by any other means. Neither of the included completed studies considered health-related quality of life. The overall certainty of evidence for the outcomes of included studies was low to moderate. Moderate-certainty evidence shows that context-specific CFR interventions result in increased rates of CPR or defibrillation performed before EMS arrival. It remains uncertain whether this can translate to significantly increased rates of overall patient survival. When possible, further high-quality RCTs that are adequately powered to measure changes in survival should be conducted. The included studies did not consider survival with good neurological function. This outcome is likely to be important to patients and should be included routinely wherever survival is measured. We identified one ongoing study and one planned trial whose results once available may change the results of this review. As this review was limited to randomized and quasi-randomized trials, we may have missed some important data from other study types.

Plain-language summary: This review searched for high-quality research studies that considered whether mobilizing community first responders could improve survival or neurological outcome, or both, following out-of-hospital cardiac arrest in adults and children. We last searched available databases in January 2019. We found two eligible research studies with a total of 1136 participants. One study conducted in Stockholm, Sweden, and funded by the Swedish Heart-Lung Foundation, Laerdal Foundation, and Stockholm County, found that mobilizing community first responders increased the rate of CPR performed before arrival of emergency medical services (data on 665 participants). The other study was conducted in Amsterdam and surrounding areas (the Netherlands) and was funded by the Netherlands Heart Foundation and Medtronic Physio-Control. Study authors reported that when community first responders were mobilized, more patients received defibrillation before emergency medical services arrived and survived to be admitted to hospital (data on 469 participants). Neither study found that dispatching community first responders resulted in significantly more overall survivors (data on 612 participants in one study and on 469 participants in the other). Neither study reported on the neurological function of survivors or on their health-related quality of life. Further research is needed to establish whether mobilizing community first responders can yield more survivors of cardiac arrest. Future research should consider both survival and the neurological function of survivors. The certainty of available evidence in terms of overall patient survival was considered low. The certainty of available evidence in terms of performance of CPR and defibrillation before arrival of emergency medical services and in terms of survival to hospital admission was considered moderate. This evidence is current to January 2019.