Table 6

Outcomes quality of evidence according to the Grades of Recommendation, Assessment, Development, and Evaluation (GRADE) approach

OutcomesNumber of studies
(number of patients)
DesignFindings and directionGRADE
Postconcussion symptoms18 studies
ObservationalImportant heterogeneity in populations enrolled, definitions of outcome variables and evaluation duration. Only four associations between postconcussion symptoms and a biomarker were statistically significant. Only eight studies used multivariate regression analyses and CIs were often large.Low
GOS-E and GOSNine studies
ObservationalSlight discrepancies in definitions, wide differences in populations enrolled, methods quality as well as in evaluation duration and inconsistencies in associations (only three were significant), their direction and strength.Insufficient
Return to workFour studies
ObservationalSlight discrepancies in definitions and reporting but considerable differences in evaluation duration (1 week–1 year). Only one study showed a significant association with increased S-100β protein serum level.Insufficient
  • GOS, Glasgow Outcome Scale; GOS-E, Glasgow Outcome Scale-Extended.