Accuracy of self-reported length of coma and posttraumatic amnesia in persons with medically verified traumatic brain injury.

OBJECTIVE To determine the accuracy of self-reported length of coma and posttraumatic amnesia (PTA) in persons with medically verified traumatic brain injury (TBI) and to investigate factors that affect self-report of length of coma and PTA duration. DESIGN Prospective cohort study. SETTING Specialized rehabilitation center with inpatient and outpatient programs. PARTICIPANTS Persons (N=242) with medically verified TBI who were identified from a registry of persons who had previously participated in TBI-related research. INTERVENTION Not applicable. MAIN OUTCOME MEASURES Self-reported length of coma and self-reported PTA duration. RESULTS Review of medical records revealed that the mean medically documented length of coma and PTA duration was 6.9±12 and 19.2±22 days, respectively, and the mean self-reported length of coma and PTA duration was 16.7±22 and 106±194 days, respectively. The average discrepancy between self-report and medical record for length of coma and PTA duration was 8.2±21 and 64±176 days, respectively. Multivariable regression models revealed that time since injury, performance on cognitive tests, and medical record values were associated with self-reported values for both length of coma and PTA duration. CONCLUSIONS In this investigation, persons with medically verified TBI showed poor accuracy in their self-report of length of coma and PTA duration. Discrepancies were large enough to affect injury severity classification. Caution should be exercised when considering self-report of length of coma and PTA duration.