Rate of Disorders of Consciousness in a Prospective Population-Based Study of Adults With Traumatic Brain Injury

OBJECTIVE: Establish rate of disorders of consciousness (DOC) and course of recovery in adults who have sustained severe traumatic brain injury (sTBI). SETTING: Four Norwegian neurosurgical departments. PARTICIPANTS: Vegetative or minimally conscious patients. DESIGN: Prospective, longitudinal population-based study of adults with sTBI with follow-ups at 3, 12, and 24-36 months postinjury. MAIN MEASURES: Coma Recovery Scale-Revised, Glasgow Coma Scale, Extended Glasgow Outcome Scale, and Disability Rating Scale. RESULTS: Three months postinjury, 2% of the sTBI population remained in a vegetative or minimally conscious state, reduced by the half after 1 year, corresponding to average annual age-adjusted incidence rates of DOC of 0.09 per 100 000 3 months post-sTBI. At 3 and 12 months, the incidence was 0.06 and 0.01 per 100 000 for the vegetative state and 0.03 and 0.04 per 100 000 for the minimally conscious state. Diagnostic categorization was stable between 12 and 24-36 months, although clinically relevant improvements were observed in minimally conscious patients. CONCLUSION: The data suggest that prolonged DOC is rare following sTBI in Norway, contrary to the commonly held belief that improvements in intensive care treatment have resulted in an increased incidence of DOC. Prolonged DOC was associated with severity of injury, subcortical lesions, and diffuse axonal injury.