Classification schema of posttraumatic amnesia duration-based injury severity relative to 1-year outcome: analysis of individuals with moderate and severe traumatic brain injury.

Objective: Early investigations classified traumatic brain injury (TBI) severity according to posttraumatic amnesia (PTA) duration, designating "greater than 7 days" as the most severe. PTA durations of more than 7 days are common in neurorehabilitation populations. Moreover, no study has derived a PTA severity schema anchored to late outcome. The purpose of this study was to develop a PTA severity classification schema.

Design: Prospective observational study.

Setting: Rehabilitation hospital.

Participants: Sample included TBI Model System participants (N=280) with known or imputed PTA duration during acute hospitalization and 1-year productivity status. Participants were primarily male (70%), median age of 27 years; and the most common mechanism of injury was motor vehicle collisions (79%). For study purposes, 4 injury severity groups were identified by observing differences in productivity associated with different PTA durations.

Interventions: None.

Main Outcome Measure: Productivity status at 1 year postinjury.

Results: Fisher exact test comparisons revealed significant differences among 3 of the groups. Most individuals with PTA fewer than 14 days had favorable 1-year outcome (68% productive), whereas worse outcomes were associated with PTA more than 28 days (18% productive).

Conclusions: If validated by other investigators, the proposed schema will be useful in determining prognosis for late functional status based on PTA duration.