Abstract
The study by Ogura et al. investigated the association between the structures of intensive care units (ICUs) affecting patient outcomes. A major limitation of this study is that the types of ICUs had not clearly been defined, and the provided definition had been made subjectively. Making an additional questionnaire or site-visits to completely define the types and to clarify the time-coverage is suggested. It would also be worthwhile to analyze whether the existence and density of "certified intensivists" and their involvement contribute to the outcome to determine whether physician quality affects critically ill patient care.