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 (n=3846) 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<0.0001). The AUC for the Russell intervals was 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 intervals.
- Head injury
- cognitive neuropsychology
- post-traumatic amnesia
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Funding The contents of this manuscript were developed under grants from the National Institute on Disability and Rehabilitation Research, Department of Education (H133A060038 (TBI Model System National Data and Statistical Center), H133B090023 (Rehabilitation Research and Training Center on Developing Stategies to Foster Community Integration and Participation for Individuals With Traumatic Brain Injury), H133A070043 (Texas TBI Model System of TIRR), H133A070040 (Moss TBI Model System), H133A-080044 (Southeastern Michigan TBI System), H133A070036 (Virginia Commonwealth TBI Model System), H133A070027 (North Texas TBI Model System), H133A070042 (Carolinas Traumatic Brain Injury Rehabilitation and Research System)).
Competing interests None.
Ethics approval Ethics approval was provided by the Methodist Rehabilitation Center, Jackson, Mississippi; James A Haley Veterans Hospital, Tampa, Florida; TIRR Memorial Hermann, Baylor College of Medicine, Houston, Texas; Shepherd Center, Atlanta, Georgia; Moss Rehabilitation Research Institute, Philadelphia, Pennsylvania; Wayne State University School of Medicine, Detroit, Michigan; Virginia Commonwealth University, Richmond, Virginia; Baylor Institute of Rehabilitation, Dallas, Texas; Carolinas Rehabilitation, Charlotte, North Carolina.
Provenance and peer review Not commissioned; externally peer reviewed.