A multicentre observational study of inter-hospital transfer for post-resuscitation care after out-of-hospital cardiac arrest.

Aim: To provide therapeutic hypothermia (TH) to survivors after out-of-hospital cardiac arrest (OHCA), inter-hospital transfers (IHT) are frequently required. The safety of IHT remains controversial. The aim of this study was to investigate whether the effect of TH on brain recovery after OHCA differs between IHT and direct arrival groups.

Methods: We identified patients with OHCA of presumed cardiac aetiology who were resuscitated by emergency medical services and experienced return-of-spontaneous circulation in 27 hospitals between January and December 2014. The main exposure variables were TH and IHT. The primary endpoint was discharge with good neurological recovery. We compared outcomes between the TH and non-TH groups using multivariable logistic regression with an interaction term between TH and IHT, after adjusting for potential confounders.

Results: Among 1616 patients, 576 patients were included in the final analyses. Neurologic recovery was better in the TH group (46.2%) than in the non-TH group (20.1%) (adjusted odds ratio [aOR] 2.03 [95% confidence interval (CI) 1.24-3.33]). In the interaction model for the outcome of good neurological recovery, the aOR for TH was 2.82 (95% CI 1.59-5.01) in the direct transfer group vs. 0.76 (95% CI 0.29-2.01) in the IHT group. The measure of interaction on the multiplicative scale in this model was also statistically significant (OR 0.27 [95% CI 0.07-0.83]; p=0.02).

Conclusion: IHT modified the effect of TH on neurological recovery for survivors of OHCA. TH is significantly less beneficial for good neurological recovery in patients who arrive via IHT than for those who arrive directly.