Evaluation of GFAP, UCH-L1 and S100B Blood Biomarkers for the Management of Sports-Related Concussion in Professional Rugby Players: A Prospective Observational Study

BACKGROUND: The incidence of sports-related concussion (SRC) in rugby has been rising in recent years. The Head Injury Assessment (HIA) protocol, used to manage SRC, is limited by its reliance on subjective symptom reporting. Blood biomarkers such as glial fibrillary acidic protein (GFAP), ubiquitin C-terminal hydrolase L1 (UCH-L1) and S100B could serve as complementary objective tools for SRC management. RESULTS: A prospective cohort study was conducted in a French elite professional rugby team (Association Montferrandaise Clermont Auvergne Sports, Association Sportive Montferrandaise Clermont Auvergne). A total of 68 professional rugby players were followed from September 2022 to June 2024. During this study period, 23 SRC episodes with blood samples collected according to the HIA protocol were included. S100B baseline levels remained stable across the season in control players. For GFAP and UCH-L1, all baseline values were consistently below the measurable range limits (GFAP < 30 ng/L and UCH-L1 < 200 ng/L). At 2 h post-match (in the absence of SRC), both S100B and UCH-L1 levels increased significantly and were positively correlated with contact frequency, whereas GFAP levels showed no significant change at this early timepoint. At the 36-h post-match follow-up, concentrations of all three biomarkers had returned to baseline, supporting the use of this timepoint within the validated HIA protocol. At 36 h following SRC, UCH-L1 concentrations remained below the quantifiable range, suggesting that earlier sampling may be required to capture post-injury changes for this biomarker. At this timepoint, an increase in S100B of ≥ 15% from baseline yielded 100% specificity (SP) and 39% sensitivity (SE) for SRC diagnosis. Elevated GFAP concentrations (≥30 ng/L) were observed in some players with SRC, providing 100% SP and 17% SE. Combining S100B and GFAP maintained 100% SP while improving SE to 52%. CONCLUSION: At 36 h post-match, both GFAP and S100B demonstrated 100% SP for the diagnosis of SRC in professional rugby players. Their integration into routine HIA assessments may offer objective support to clinical decision-making and help enhance player safety.