Serum S100B and Its Interplay With hs‐CRP and Platelet Count in Association With Adverse Outcomes After Ischemic Stroke

Background S100B (serum S100 calcium‐binding protein B) has been linked to blood–brain barrier disruption and neuroinflammation, but its prognostic value for ischemic stroke remains controversial. We aimed to examine baseline serum S100B and its interplay with high‐sensitivity C‐reactive protein and platelet count in association with clinical outcomes after ischemic stroke. Methods Data were derived from a prospective multicenter cohort involving 3249 patients with acute ischemic stroke in 26 hospitals across China. Serum S100B concentrations were measured at baseline, and patients were followed up for 3 months after ischemic stroke. Study outcomes included death, major disability, and vascular events. Multivariable‐adjusted Cox proportional hazards regression models and logistic regression models were applied to estimate hazard ratios (HRs) or odds ratios (ORs) and their 95%CIs. Results During the 3‐month follow‐up, 92 (2.8%) patients died. Higher baseline serum S100B levels were associated with an increased risk of death (quartile 4 versus quartile 1: adjusted HR, 2.09 [95% CI, 1.09–4.02]; P trend =0.028). Each SD increase in log‐transformed serum S100B was associated with a 38% greater risk of death. A spline regression model showed a linear relationship between serum S100B and death risk ( P linearity =0.006). Significant joint effects were observed between S100B and high‐sensitivity C‐reactive protein, and between S100B and platelet count, in association with death after ischemic stroke. The highest risk was observed among patients with elevations in all 3 biomarkers. Conclusions Elevated serum S100B levels in the acute phase of ischemic stroke were independently associated with increased mortality risk. A single combined measure of S100B, high‐sensitivity C‐reactive protein, and platelet count may further improve risk stratification. Registration URL: https://www.clinicaltrials.gov ; Unique Identifier: NCT01840072.