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-of-hospital 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 frequency-weighted 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 < 0.001). A statistically significant decrease in risk of mortality in group 2 vs. group 1 (risk ratio 0.988, 95% CI 0. 985-0.0.992, P < 0.001) and in group 3 vs. group 2 (risk ratio 0.967, 95% CI 0.964-0.971, P < 0.001) was observed. Similar trends were observed for return of spontaneous circulation and survival to hospital admission.

Conclusion: Survival to hospital discharge after OHCA has significantly improved. Many aspects may influence survival, but surely, the reduction of time and an early and good quality CPR have positively influenced the outcome.