The Canadian CT head rule study for patients with minor head injury: Rationale, objectives, and methodology for phase I (derivation)

Head injuries are among the most common types of trauma seen in North Ameri can emergency departments, with an estimated I million cases seen annually. "Minor" head injury (sometimes known as "mild") is defined by a history of loss of consciousness, amnesia, or disorientation in a patient who is cons cious and talking, that is, with a Glasgow Coma Scale Although most patient s with minor head score of 13 to 15. injury can be discharged without seque lae after a period of observation, in a small proportion, their neurologic condition deteriorates and requires neurosurgical intervention for intracra nial hematoma. The objective of the Canadian CT Head Rule Study is to devel op an accurate and reliable decision rule for the use of computed tomograph y (CT) in patients with minor head injury. Such a decision rule would allow physicians to be more selective in their use of CT without compromising ca re of patients with minor head injury. This paper describes in detail the r ationale, objectives, and methodology for Phase I of the study in which the decision rule was derived.