Improving bystander automated external defibrillation application in Singapore: An 11-year population-based living-laboratory study

Background Bystander automated external defibrillator (BAED) use improves out-of-hospital cardiac arrest (OHCA) outcomes but remains uncommon globally. This study evaluated the outcomes of Singapore's 11-year public-access AED expansion and volunteer-responder implementation in terms of trends in BAED use, associated factors, and clinical outcomes. Methods This population-based, retrospective cohort study used Singapore Pan-Asian Resuscitation Outcomes Study (SG-PAROS) data (2010-2020) for adult, non-traumatic OHCAs. The primary outcome was bystander AED application. Multivariable logistic regression identified factors associated with use. Secondary outcomes included favorable neurological status (CPC 1-2), survival to discharge, and prehospital return of spontaneous circulation (ROSC). Results Of 21,439 included OHCA cases (median age 70.0 years; 63.8% male), BAED use increased from 1.7% to 9.6% over 11 years, with a corresponding increase in overall survival from 2.4 to 4.0%. Malay ethnicity (aOR 1.25, 1.06-1.49), calendar year (aOR 1.26, 1.22-1.29), and delayed emergency medical services (aOR 1.24, 1.06-1.45) were positive predictors of BAED use. Conversely, BAED use was lower among females (aOR 0.80, 95% CI 0.69-0.94), at night (aOR 0.69, 0.56-0.86), and in residential settings (aOR 0.06, 0.05-0.07). Volunteer arrival strongly increased application (aOR 4.16, 3.41-5.09), with a significant interaction (p<0.001); the effect was greater in residential (aOR 7.38, 5.81-9.38) than non-residential settings (aOR 1.71, 1.22-2.40). AED use predicted favorable neurological outcome (aOR 2.80, 2.24-3.50; NNT 8.7), survival (aOR 2.30, 1.89-2.80), and ROSC (aOR 2.11, 1.81-2.46). Conclusion Over 11 years, we saw a significant increase in BAED application and favorable neurological survival. This success was associated with the implementation of an integrated strategy combining widespread AED deployment, national training, and smartphone-activated volunteer responders. Singapore's experience provides a scalable model for urban centers seeking to expand their AED strategy.