Method of Patient Selection and Design of the Investigation

Abstract

The principal purpose of this study was to assess the long-term effect of a single head injury in a series of patients, unselected except by clearly defined criteria of severity. It was also intended that every patient included in the study should be traced and all the survivors examined. Similarly, the cause of death was to be established in every case dying since the injury so that any effect the head injury had on life expectancy could be determined. In general terms, therefore, this was designed as an epidemiological study of an unselected sample of patients with the severest injuries from a population of patients who had sustained head injury considered serious enough to warrant their admission to hospital. In this way it was hoped to avoid the type of selection bias which limits the value of many previously reported studies, prevents comparisons between one study and another, and makes it difficult to formulate general statements about the ultimate outcome for specific neural disabilities which follow severe non-missile brain injury.