Third, because this study is a single-center retrospective study, selection bias should be discussed. We recently published a study on the impact of the GCS motor score at admission on neurological outcomes in out-of-hospital cardiac arrest patients receiving therapeutic hypothermia [2] In our study, 25 % (1/4) of patients with GCS motor score 5 had a poor neurological outcome despite MTH; however, 52 % (130/249) of patients with an initial GCS motor score of 1 who underwent MTH had good neurological outcomes. However, in the study by Natsukawa et al., patients with GCS motor score 1 who underwent MTH had extremely poor outcome [favorable neurological outcome; 7/53 (13.2 %) (Table two)]. This was considered to be due to the existence of patients with cardiopulmonary arrest of non-cardiac origin. Therefore, this study group contained a more heterogeneous population, which makes it more difficult to interpret the study results.