Methodological issues in the study of inter-hospital transfer in low-volume and high-volume emergency departments and survival outcomes after out-of-hospital cardiac arrest

摘要

To the Editor, We read with great interest the article by Park and colleagues, whofound that inter-hospital transfer (IHT) group had better neurological recovery than the non-IHTgroup in low-volume emergency departments (LVEDs) visitors, while for the patients in high-volume emergency departments (HVEDs), the IHT group did not show better neurological recovery than the non-IHT group. Though this study sounds scientific, some critical methodological issues should be discussed. First, Park et al. aimed to investigate the association between IHT and outcomes of out-of-hospital cardiac arrest (OHCA) and many potential confounders had been matched in the multivariable logistic model, however some important confounders of post-resuscitation management, including percutaneous coronary intervention (PCI), extracorporeal membrane oxygenation and targeted temperature management, were unbalanced between the IHT group and non-IHT group, which might affect the final results. Interestingly in 2016, the same research group published a study which demonstrated that therapeutic hypothermia (TH) was more beneficial for good neurological recovery in the patients who arrived via IHT than those who arrived via IHT and IHT modified the effects of TH on neurological recovery for survivors of OHCA