Feasibility and Utility of a Flexible Outcome Assessment Battery for Longitudinal Traumatic Brain Injury Research: A TRACK-TBI Study

Abstract

The effects of traumatic brain injury (TBI) are difficult to measure in longitudinal cohort studies, because disparate pre-injury characteristics and injury mechanisms produce variable impairment profiles and recovery trajectories. In preparation for the Transforming Research and Clinical Knowledge in TBI (TRACK-TBI) study, which followed patients with injuries ranging from uncomplicated mild TBI to coma, we designed a multi-dimensional Flexible outcome Assessment Battery (FAB). The FAB relies on a decision-making algorithm that assigns participants to a Comprehensive (CAB) or Abbreviated Assessment Battery (AAB) and guides test selection across all phases of recovery. To assess feasibility of the FAB, we calculated the proportion of participants followed at 2 weeks (2w) and at 3, 6, and 12 months (3m, 6m, 12m) post-injury who completed the FAB and received valid scores. We evaluated utility of the FAB by examining differences in 6m and 12m Glasgow Outcome Scale-Extended (GOSE) scores between participant subgroups derived from the FAB-enabled versus traditional approach to outcome assessment applied at 2w. Among participants followed at 2w (n = 2094), 3m (n = 1871), 6m (n = 1736), and 12m (n = 1607) post-injury, 95-99% received valid completion scores on the FAB, in full or in part, either in person or by telephone. Level of function assessed by the FAB-enabled approach at 2w was associated with 6m and 12m GOSE scores (proportional odds p < 0.001). These findings suggest that the participant classification methodology afforded by the FAB may enable more effective data collection to improve detection of natural history changes and TBI treatment effects.

Keywords: assessment; feasibility; outcome assessment; traumatic brain injury.

FIG. 1.

Flexible Assessment Battery (FAB) decision tree. The examiner begins the FAB by administering a Screening Protocol (SP), which comprises a verbal expression task to ensure that the participant is not aphasic and can speak intelligibly, and the Galveston Orientation and Amnesia Test (GOAT) to assess for ongoing post-traumatic amnesia (PTA). If speech is intelligible and the total GOAT score is >75, the participant progresses to the Comprehensive Assessment Battery (CAB). If speech is intelligible but the participant remains in PTA based on the GOAT (total ≤75), the Cognitive Impairment subscale of the Confusion Assessment Protocol (CAP-Cog) is administered to assess for post-traumatic confusion. If the CAP-Cog score is in the non-confused range (>18), the participant progresses to the CAB. If the CAP-Cog score is in the confused range (≤18), the Glasgow Outcome Scale Extended (GOSE) and Disability Rating Scale (DRS) are completed by the surrogate, concluding the assessment. If the participant is nonverbal because of aphasia or disturbance in consciousness, the Coma Recovery Scale-Revised (CRS-R) is administered. If CRS-R discontinuation criteria are met (Auditory subscale = 4 and Communication subscale = 2 and Arousal subscale = 3), the CAP-Cog is administered and the assessment proceeds as described above. If CRS-R discontinuation criteria are not met, the surrogate completes the GOSE and DRS and the follow-up concludes. At each subsequent follow-up, participants begin with the same battery they were assigned to previously and follow the decision tree, unless there is evidence of a decline in function as judged by the examiner, in which case assessment begins with the SP. The FAB decision tree facilitates assessment of participants across the spectrum of severity, providing examiners with clear guidelines for administration of standardized measures that are appropriate to the participant's current level of function. Additional details about each measure are available in Supplementary Table 1 and by accessing the online TRACK-TBI Standard Operating Procedure (SOP) Manual for Outcome Assessment.

FIG. 2.

Participant flow diagram. Of 2551 adults with traumatic brain injury (TBI), 2209 (87%) were followed (i.e., completed at least the Glasgow Outcome Scale Extended [GOSE]) at one or more time points. FAB, Flexible Assessment Battery; CAB, Comprehensive Assessment Battery; AAB, Abbreviated Assessment Battery.

FIG. 3.

Proportion of participants' 6-month Glasgow Outcome Scale Extended (GOSE) scores by category based on the traditional and Flexible Assessment Battery (FAB)-enabled approaches to assessment at two weeks post-injury. The FAB-enabled approach to assessment generated four distinct subgroups with marked differences in GOSE outcome at 6m. (A) When participants who were unable to be assessed using standard neuropsychological testing were assigned to the Abbreviated Assessment Battery (AAB) at 2w and combined into a single group (i.e., traditional approach), the median 6m GOSE score was 3 (Lower Severe Disability), which is 4 points lower than the median score for participants assigned to the Comprehensive Assessment Battery (CAB) group (7- Lower Good Recovery). (B) When AAB participants were classified by level of function into four subgroups using the Coma Recovery Scale-Revised (CRS-R) and Confusion Assessment Protocol (CAP-Cog) measures in the FAB, the median 6m GOSE score for the minimally conscious state plus (MCS with evidence of language function (MCS+_AAB) and post-traumatic confusional state (PTCS_AAB) subgroups was 2 points higher (5- Lower Moderate Disability) than the 6m GOSE score estimated using the traditional approach (3- Lower Severe Disability). GR, good recovery; MD, moderate disability; SD, severe disability; VS, vegetative state; MCS-, minimally conscious state minus (MCS without evidence of language function).

FIG. 4.

Proportion of participants' 12-month Glasgow Outcome Scale Extended (GOSE) scores by category based on the traditional and Flexible Assessment Battery (FAB)-enabled approaches to assessment at two weeks post-injury. The FAB-enabled approach to assessment generated four distinct subgroups with marked differences in GOSE outcome at 6m. (A) When participants who were unable to be assessed using standard neuropsychological testing were assigned to the Abbreviated Assessment Battery (AAB) at 2w and combined into a single group (i.e., traditional approach), the median 12m GOSE score was 4 (Upper Severe Disability), which is 3 points lower than the median score for participants assigned to the Comprehensive Assessment Battery (CAB) group at 2w (7- Lower Good Recovery). (B) When AAB participants were classified by level of function at 2w into four subgroups using the Coma Recovery Scale-Revised (CRS-R) and Confusion Assessment Protocol (CAP-Cog) measures in the FAB, the median 12m GOSE score was 1 point higher for the minimally conscious state plus (MCS with evidence of language function (MCS+_AAB ) subgroup (5- Lower Moderate Disability) and 2 points higher for the post-traumatic confusional state (PTCS_AAB) subgroup (6- Upper Moderate Disability) when compared with the 12m GOSE score estimated using the traditional approach (4- Upper Severe Disability). GR, good recovery; MD, moderate disability; SD, severe disability; VS, vegetative state.