The SCRAP Rule: The derivation and internal validation of a clinical decision rule for computed tomography of the chest in blunt thoracic trauma.

Objective: To derive and internally validate a clinical decision rule that will rule out major thoracic injury in adult blunt trauma patients, reducing the unnecessary use of chest computed tomographic (CT) scans.

Methods: Data were retrospectively obtained from a chart review of all trauma patients presenting to a Canadian tertiary trauma care centre from 2005 to 2008, with those from April 2006 to March 2007 being used for the validation phase. Patients were included if they had an Injury Severity Score > 12 and chest CT at admission or a documented major thoracic injury noted in the trauma database.