Traumatic Brain Injury: What Is a Favorable Outcome?

Traumatic brain injury (TBI) results in disparate outcomes ranging from persistent disorders of consciousness to symptom resolution. Despite the breadth and complexity of TBI recovery, most clinical trials dichotomize outcome by establishing an arbitrary cut-point, above and below which recovery is described as "favorable" and "unfavorable," respectively. For example, the widely used eight-level Glasgow Outcome Scale-Extended (GOSE) is typically collapsed into these two categories. Dichotomizing the GOSE into "favorable" and "unfavorable" outcome may limit detection of treatment effects in TBI clinical trials, contribute to imprecise prognostic counseling, and unduly influence decision-making with regard to withdrawal of life-sustaining therapy. We illustrate the lack of standardization in defining "unfavorable" and "favorable" TBI outcome on the GOSE by identifying the broad range of cut-points, from a score of 3 (part-time supervision in the home required) to 7 (presence of some residual of symptoms), that have been used to dichotomize the GOSE. We also highlight the ethical concerns related to characterizing TBI outcomes solely from the perspective of investigators and clinicians, rather than patients and caregivers. Finally, we suggest that a pragmatic, immediate solution to GOSE dichotomization is to report the likelihood of achieving each of the eight GOSE outcome levels and propose a study design for a new patient- and caregiver-centered TBI outcome metric.