Do early emergency calls before patient collapse improve survival after out-of-hospital cardiac arrests?

Abstract Aim Some out-of-hospital cardiac arrests (OHCAs) are witnessed after emergency calls. This study aimed to confirm the benefit of early emergency calls before patient collapse on survival after OHCAs witnessed by bystanders and/or emergency medical technicians (EMTs). Methods We analysed 278,310 witnessed OHCAs [EMT-witnessed cases ( n  = 54,172), bystander-witnessed cases ( n  = 224,138)] without pre-hospital physician involvement from all Japanese OHCA data prospectively collected between 2006 and 2012. The data were analysed for the correlation between neurologically favourable 1-month survival and the time interval between the emergency call and patient collapse. Results When emergency calls were placed earlier before patient collapse, the proportion of EMT-witnessed cases and survival rate after OHCAs witnessed by bystanders and EMTs were higher. When analysed only for bystander-witnessed cases, for earlier emergency calls placed before patient collapse, survival rate and incidences of bystander cardiopulmonary resuscitation (CPR) and dispatcher-assisted CPR decreased: 2.9%, 33.6% and 24.4%, respectively, for emergency calls placed >6 min before collapse and 5.5%, 48.8% and 48.5%, respectively, for those placed 1–2 min after collapse. Multivariable logistic regression showed that call-to-collapse interval (adjusted odds ratio; 95% confidence interval) (0.92; 0.90–0.94) and EMT response time after collapse (0.84; 0.82–0.86) were associated with survival after bystander-witnessed OHCAs with emergency calls before collapse. Conclusion Early emergency calls before patient collapse efficiently increases the proportion of EMT-witnessed cases and promotes survival after witnessed OHCAs. However, early emergency call before collapse may worsen the outcome when the patient's condition deteriorates to cardiac arrest before EMT arrival.