If someone aims to prove his or her idea, comparison with the opposite idea is required. In trauma management, it is often difficult to conduct prospective, randomized, controlled trials, which can adjust known and even unknown confounding factors. Thus, in most instances, we have to conduct observational studies, which can control only known factors. For maintaining high reliability, we must gather a large number of data sets and use key techniques of epidemiology based on statistics, which are often complicated. In this review, I would like to demonstrate the easiest way to carry out high quality, observational studies for clinicians who are in charge of everyday trauma management.

　　The new classification for trauma surgeons, the 2008 classification of organ injury, was explored by the Committee of Classification of Organ Injury in the Japanese Association for the Surgery of Trauma (JAST). The 2008 classification of organ injury was revised from the former classification of organ injury proposed by JAST from 1997 to 2000, and was improved by advances in diagnostic imaging and treatment, including surgical intervention. The results of questionnaire to a regular member of JAST, and to the critical care center, or to the hospital submitting data to the Japan Traumatic Date Bank (JTDB), has proved that the classification has been used commonly among trauma surgeons.

　　The classification of traumatic brain injury was proposed by JAST and the Japan Society of Neurotraumatology (JSTN). The classification was established by the combination of the classification of head injury by Gennarelli, the Japanese advanced trauma evaluation and care (JATEC), and the guidelines for the treatment and management of severe head injury by JSNT. Cases with impending cerebral herniation signs based on neurological findings and by CT imaging were defined as severe, and are treated by neurosurgery and/or by neurosurgical ICU.

　　These new classifications are expected to be used by trauma surgeons working in the emergency room.