Cross-validation of a classification system for persons with traumatic brain injury in the posthospital period

Objective: To (1) identify groupings of persons with traumatic brain injury (TBI) in the posthospital period in a cohort recruited in Australia; (2) compare groupings from the Australian cohort to groupings previously developed for a US cohort. Setting: Rehabilitation centers in the US and Australia. Participants: A total of 170 persons with TBI from Australia and 504 persons with TBI from the United States. Participants were aged 18 to 64 years, greater than 6 months postinjury, had capacity to give consent, and had definitive contemporaneous medical evidence of TBI. Design: Observational study. Main Measures: Cognitive tests—Wechsler Letter-Number Sequencing and Coding, Rey Auditory Verbal Learning Test, Trail Making Test, Verbal Fluency. Questionnaires—9 scales from the Traumatic Brain Injury Quality-of-Life system; Neurobehavioral Symptom Inventory; Economic Quality of Life, Family Assessment Device—General Functioning. Performance validity—Word Memory Test. Results: Agreement in classification for the 2 samples was only moderate with 63.5% correctly classified and Cohen’s κ = 0.53. A post hoc analysis placing all persons showing poor performance validity in the same group improved classification to 73% and Cohen’s κ= 0.65 indicating substantial agreement. Conclusion: Results provided support for the patient groups developed for the US sample and indicate that these groupings largely replicated in a new cohort