Background Out-of-hospital cardiac arrest (OHCA) remains a leading cause of death, with survival highly dependent on early cardiopulmonary resuscitation (CPR) and defibrillation. Crowdsourcing technologies that alert nearby volunteers via text messages or smartphone applications aim to shorten response times and strengthen the chain of survival. A 2021 scoping review highlighted substantial heterogeneity and limited outcome data. This study provides an updated synthesis of the literature. Methods A scoping review was conducted in accordance with PRISMA-ScR guidelines. PubMed, Scopus, and ClinicalTrials were searched through 31 December 2024. Randomized and observational studies reporting original data on crowdsourcing technologies alerting lay responders to suspected OHCA were included. Data were extracted on study characteristics, technology features, volunteer participation, OHCA characteristics, and outcomes. Results Thirty-seven studies met inclusion criteria mainly from Europe (Netherlands, Denmark, Sweden). Smartphone-based systems were evaluated in 22 studies, text message–based in 13, and both in 2. Alerts were triggered by emergency medical services, with location provided via GPS or text. Prior BLS training was required in 65% of studies, and automated role allocation was present in 62%. Reporting of volunteer metrics and patient outcomes was inconsistent. Among 10 studies with detailed data, arrival before EMS, bystander CPR, bystander defibrillation, ROSC and survival rates varied widely. Post-resuscitation outcomes were infrequently reported. Conclusions Crowdsourcing technologies may facilitate earlier bystander intervention in OHCA. However, heterogeneity in system design and outcome reporting limits comparability and limits conclusions about clinical effectiveness. Future research should standardize reporting of key volunteer, response, and patient-centered metrics.
Mavrovounis et al. (Mon,) studied this question.