Journal:J Neurol Neurosurg Psychiatry.
Year, Volume, Issue, Page(s):11, 82, 5, 494-499
Background: Duration of post-traumatic amnesia (PTA)
correlates with global outcomes and functional disability.
Russell proposed the use of PTA duration intervals as an
index for classification of traumatic brain injury (TBI)
severity. Alternative duration-based schemata have been
recently proposed as better predictors of outcome to the
commonly cited Russell intervals.
Objective: Validate a TBI severity classification model
(Mississippi intervals) of PTA duration anchored to late
productivity outcome, and compare sensitivity against
the Russell intervals.
Methods: Prospective observational data on TBI Model
System participants (n¼3846) with known or imputed
PTA duration during acute hospitalisation. Productivity
status at 1-year postinjury was used to compare
predicted outcomes using the Mississippi and Russell
classification intervals. Logistic regression
model-generated curves were used to compare the
performance of the classification intervals by assessing
the area under the curve (AUC); the highest AUC
represented the best-performing model.
Results: All severity variables evaluated were individually
associated with return to productivity at 1 year (RTP1).
Age was significantly associated with RTP1; however,
younger patients had a different association than older
patients. After adjustment for individually significant
variables, the odds of RTP1 decrease by 14% with every
additional week of PTA duration (95% CI 12% to 17%;
p significantly smaller than the Mississippi intervals.
Conclusions: PTA duration is an important predictor of
late productivity outcome after TBI. The Mississippi PTA
interval classification model is a valid predictor of
productivity at 1 year postinjury and provides a more
sensitive categorisation of PTA values than the Russell