Association between early advanced life support and good neurological outcome in out of hospital cardiac arrest: A propensity score analysis

BACKGROUND: Out-of-hospital cardiac arrest (OHCA) is an important public health problem. The French organization, combining OHCA basic life support (BLS) and advanced life support (ALS), has been recently questioned. The study was conducted to evaluate the association between early ALS (E-ALS) arrival and good neurological outcome at 1 month in nontraumatic OHCA patients. MATERIALS AND METHODS: Retrospective cohort study using data from ReAC, multicentre OHCA database since June 2011. Adult patients with nontraumatic cardiac arrest were identified, and firefighters' (BLS) arrival time was recorded. The main analysis was performed after multiple imputation, using propensity score matching with a variable ratio. Sensitivity analyses were also performed. The exposure was early ALS (E-ALS), start of ALS before. or simultaneously with BLS. The primary outcome was the cerebral performance category (CPC) at day 30 after the cardiac arrest (1-2 vs 3-5), while cumulative incidence of return of spontaneous circulation (ROSC) defined secondary outcomes. RESULTS: Between January 2013 and January 2016, a total of 30 672 adult nontraumatic OHCA with resuscitation were identified, from whom 20 804 were included, 2711 in the E-ALS group and 18 093 in the control group. Based on the matched sample, patients in the E-ALS group had a significantly lower rate of good neurological outcome than those in the control group (OR, 0.95; 95% CI, 0.93-0.96). Sensitivity analyses were mostly consistent with this result. Cumulative incidence of ROSC was higher in delayed ALS (D-ALS) group. CONCLUSIONS: This study showed that patients in the E-ALS group were less likely to have a good neurological outcome. One explanation of this unexpected result could be the total duration of resuscitation performed, which may be interrupted prematurely in cases of E-ALS.