The Relationship between Emergency Response Time and Out-Of-Hospital Cardiac Arrest Prognosis: A Meta-Analysis

Abstract

Objective To assess the relationship between emergency response time and prognosis of patients with out-of-hospital cardiac arrest. Design Systematic review. Methods Relevant observational studies were identified by a search of PubMed and ISI databases to 30 January 2014. Primary outcome was survival to discharge. The weighted mean differences (WMD) for response time were calculated for those survivals to discharge and death in hospital. We also carried out a dose response meta-analysis for assessing summary odds ratio (OR) of survival by response time. Results A total of 13 studies with 804,998 patients included in the meta-analysis. The WMD of response time between survivals to discharge group and death in hospital group was 1.976 (95% confidence interval [CI] = 1.161-2.792; p<0.001). Sensitivity analyses by only included prospective cohorts showed the WMD of response time between two groups was 1.115 (95% CI=0.508-1.723; p<0.001). Dose-response relationship between response time and survival to discharge risk was observed statistically significant (χ2=39.86, p<0.001). In linear model, the summary OR was 0.914 (95% CI=0.889-0.940) for every 1 minutes delay in response time. In spline model, the survival OR decreased along with the response time, especially when response time less than 7 minutes. Conclusions Emergency response time is an important risk factor for prognosis after OHCA in adults. The EMS team must arrive as soon as possible to the site of the event. (Hong Kong j.emerg.med. 2015;22:345-351)