Positive trend in survival to hospital discharge after out-of-hospital cardiac arrest: A quantitative review of the literature

Background Seven editions of cardiopulmonary resuscitation (CPR) and emergency cardiovascular care guidelines have been published with many changes, in particular, about CPR. Objectives The aim of our study was to evaluate the temporal trend of survival to hospital discharge after out-ofhospital cardiac arrest (OHCA) as a possible effect of guidelines changes. Methods We searched PubMed for observational studies on 'survival to hospital discharge after OHCA'. Survival to discharge was the primary outcome; prehospital return of spontaneous circulation and survival to hospital admission were our secondary endpoints. All data were analyzed according to the year of inclusion: group 1 before 2000; group 2 between 2000 and 2005; and group 3 after 2005. Mortality rates were compared between groups by means of a group frequencyweighted log-linear model. Results We considered 38 of 201 studies for a total of 156 301 patients. Survival to hospital discharge rate was 5.0% [95% confidence interval (CI) 4.9-5.2) in group 1; 6.1% (95% CI 5.9-6.4) in group 2; and 9.1% (95% CI 8.9-9.4) in group 3 (P