Prognostic Value of Interleukin-6 and High-Sensitivity C-Reactive Protein in Stroke Associated With Intracranial Atherosclerotic Stenosis.

BACKGROUND: Intracranial atherosclerotic stenosis (ICAS) is a major cause of ischemic stroke with a high recurrence risk despite guideline-based secondary prevention. Although inflammation may contribute to this residual risk, the prognostic roles of interleukin-6 (IL-6) and hsCRP (high-sensitivity C-reactive protein) in ICAS-related stroke remain unclear. METHODS: This prospective observational study enrolled 942 patients with ischemic stroke within 1 week of onset. ICAS was defined as ≥50% stenosis/occlusion. High IL-6 and hsCRP levels were defined using median cutoffs of ≥4.2 pg/mL and ≥2.0 mg/L, respectively. The primary end point was 1-year major adverse cardiovascular events (MACE), including nonfatal stroke, nonfatal acute coronary syndrome, and vascular death. RESULTS: Of the 942 patients (mean age; 71.2 years, men; 61.3%), 262 (27.8%) had ICAS. Among patients with ICAS, elevated IL-6 and hsCRP were each associated with higher MACE rates (IL-6: 15.4% versus 28.8%, log-rank P=0.012; hsCRP: 15.9% versus 28.5%, log-rank P=0.015). After multivariate adjustment, hsCRP ≥2.0 mg/L remained independently associated with MACE (hazard ratio [HR], 2.01; 95% CI, 1.12-3.59), whereas the association for IL-6≥4.2 pg/mL was attenuated (HR, 1.75; 95% CI, 0.95-3.23). Both biomarkers were associated with MACE in patients achieving low-density lipoprotein cholesterol <100 mg/dL. Receiver operating characteristic-derived cutoffs of 5.0 pg/mL for IL-6 and 2.9 mg/L for hsCRP independently predicted MACE (HR, 2.02 and 2.86, respectively). CONCLUSIONS: Baseline hsCRP may improve risk stratification in ICAS-related stroke by identifying residual inflammatory risk beyond conventional risk factors. The prognostic value of IL-6 was less robust and requires further investigation.