Background: The Cochrane Handbook suggests that “indirect or surrogate outcome measures are potentially misleading and should be avoided or interpreted with caution because … many interventions reduce the risk for a surrogate outcome but have no effect or have harmful effects on clinically relevant outcomes, and some interventions have no effect on surrogate measures but improve clinical outcomes”. This is very relevant to the field of neurorehabilitation, where tangible clinical end points that matter to the patients, such as functional independence, return to work and community integration should be preferred over surrogate measurements such as cognition, spasticity, and muscle power.
Objectives:
1. To analyze proportions of clinically relevant outcome measures versus surrogate outcomes reported in Cochrane Systematic Reviews (CSRs) on rehabilitation interventions following traumatic brain injury (TBI).
2. To analyze the proportion of individual trials in these CSRs that report clinical outcomes.
Methods: The Cochrane Library was searched for CSRs on rehabilitation interventions following traumatic brain injury. Exclusion criteria were non-traumatic etiology, and pharmacological interventions. Three authors analyzed the search results. Outcomes were extracted and categorized as clinically relevant or surrogate.
Results: Thirty-seven CSRs related to TBI were screened, five met the inclusion criteria: 18 out of 49 outcomes (37%) enlisted in five CSRs were clinically relevant outcomes; the rest were surrogate outcomes. A total of 17 trials were included in these reviews. Eight trials from two CSRs (47%) had reported at least one clinically relevant outcome. In the remaining three CSRs, no study reported any clinically relevant outcome. Meta-analysis was not done in any of the five CSRs.
Conclusions: Less than half of the outcomes reported in CSRs on TBI rehabilitation were clinically relevant. More than half of the trials included in these reviews did not report any clinically relevant outcome measure.