LAUSR

Purpose: To investigate temporal variations in dispatcher‐assisted and bystander‐initiated resuscitation efforts and their association with survival after bystander‐witnessed out‐of‐hospital cardiac arrests (OHCAs). Methods: We retrospectively analyzed the neurologically favorable 1‐month survival and the parameters related to dispatcher assisted cardiopulmonary resuscitation (DA‐CPR) and bystander CPR (BCPR) for 227,524 OHCA patients between 2007 and 2013 in Japan. DA‐CPR sensitivity for OHCAs, bystander's compliance to DA‐CPR assessed by the proportion of bystanders who follow DA‐CPR, and performance of BCPR measured by the rate of bystander‐initiated CPR in patients without DA‐CPR were calculated as indices of resuscitation efforts. Results: Performance of BCPR was only similar to temporal variations in the survival (correlation between hourly paired values, R2 = 0.263, P = 0.01): a lower survival rate (3.4% vs 4.2%) and performance of BCPR (23.1% vs 30.8%) during night‐time (22:00–5:59) than during non‐night‐time. In subgroup analyses based on interaction tests, all three indices deteriorated during night‐time when OHCAs were witnessed by non‐family (adjusted odds ratio, 0.73–0.82), particularly in non‐elderly patients. The rate of public access defibrillation for these OHCAs markedly decreased during night‐time (adjusted odds ratio, 0.49) with delayed emergency calls and BCPR initiation. Multivariable logistic regression analyses revealed that the survival rate of non‐family‐witnessed OHCAs was 1.83‐fold lower during night‐time than during non‐night‐time. Conclusions: Dispatcher‐assisted and bystander‐initiated resuscitation efforts are low during night‐time in OHCAs witnessed by non‐family. A divisional alert system to recruit well‐trained individuals is needed in order to improve the outcomes of night‐time OHCAs witnessed by non‐family bystanders.