The effect of mild therapeutic hypothermia on good neurological recovery after out-of-hospital cardiac arrest according to location of return of spontaneous circulation: A nationwide observational study

BackgroundMild therapeutic hypothermia (MTH) has been known to be associated with good neurological recovery after out-of-hospital cardiac arrest (OHCA). Prehospital return of spontaneous circulation (P-ROSC) is associated with better hospital outcomes than ROSC at emergency department (ED-ROSC). The study aims to examine the association between MTH by location of ROSC and good neurological recovery after OHCA.MethodsAdult OHCA cases with presumed cardiac etiology who survived to hospital admission were collected from a nationwide cardiac registry between 2008 and 2013. MTH was defined as a case receiving hypothermia procedure regardless of procedure method. Primary outcome was good neurological recovery with cerebral performance category score of 1 and 2. Multivariable logistic regression analysis was performed adjusting for potential confounders with an interaction term between MTH and location of ROSC to calculate adjusted odds ratios (AORs) and 95% confidence intervals (CIs).ResultsAmong 11,158 patients survived to admission, good neurological recovery was 23.6% (399/1691) in MTH vs. 15.0% (1400/9316) in non-MTH (p < 0.001), and 58.2% (1074/1864) in P-ROSC vs. 7.9% (725/9161) in ED-ROSC (p < 0.001). There was a significant association between MTH and good neurological recovery (AOR = 1.32, 95% CI = 1.11-1.57). In the interaction model, AOR of MTH and interaction effect with P-ROSC and ED-ROSC was 0.78 (0.58-2.70) and 1.68 (1.34-1.98), respectively.ConclusionMTH was significantly associated with good neurological recovery among OHCA survivors. In the interaction model, MTH showed significant benefits in patient group with ROSC at ED, not in P-ROSC group.