Interleukin-6 and YKL-40 predicted recurrent stroke after ischemic stroke or TIA: analysis of 6 inflammation biomarkers in a prospective cohort study.

OBJECTIVE: Contribution of individual and combined inflammatory markers in prognosis after stroke was still undefined. We aimed to investigate the association of systemic and local vascular inflammatory markers and recurrent stroke as well as impact on poor functional outcome. METHODS: In this pre-specified substudy of the Third China National Stroke Registry (CNSR-III), 10,472 consecutive acute ischemic stroke or TIA patients with available centralized-measured levels of Interleukin-6 (IL-6), high sensitive C-reactive protein (hsCRP), IL-1 receptor antagonist (IL-1Ra), lipoprotein-associated phospholipase A2 mass (Lp-PLA2) and activity (Lp-PLA2-A), and YKL-40 from 171 sites were enrolled. The primary outcomes consisted of stroke recurrence and poor functional outcome defined as modified Rankin Scale (mRS) score of 2-6 within 1 year. RESULTS: There were 1026 (9.8%) and 2395 (23.4%) patients with recurrent stroke and poor functional outcome within 1 year. The highest quartiles of IL-6 (adjusted HR, 1.36; 95% CI 1.13-1.64; P = 0.001), hsCRP (adjusted HR, 1.41; 95% CI 1.17-1.69; P = 0.0003) and YKL-40 (adjusted HR, 1.28; 95% CI 1.06-1.56; P = 0.01) were associated with increased risk of recurrent stroke; and the highest quartiles of IL-6 (adjusted OR 1.93; 95% CI 1.64-2.27; P < 0.0001), IL-1Ra (adjusted OR 1.60; 95% CI 1.37-1.87; P < 0.0001), hsCRP (adjusted OR 1.60; 95% CI 1.37-1.86; P < 0.0001) and YKL-40 (adjusted OR 1.21; 95% CI 1.03-1.42; P = 0.02) were correlated with increased risk of poor functional outcome. In the multivariate stepwise regression analysis including all markers with backward selection, elevated levels of IL-6 or YKL-40 were associated with recurrent stroke (IL6: OR, 1.34; 95% CI 1.19-1.52; P < 0.0001; YKL-40: OR, 1.01; 95% CI 1.01-1.03; P = 0.004) and poor functional outcome (IL6: OR, 1.68; 95% CI 1.46-1.93; P < 0.0001; YKL-40: OR, 1.02; 95% CI 1.01-1.03; P = 0.0001). Adding IL-6 and YKL-40 significantly increased the area under the receiver operating characteristic curves for the prediction models of Essen Stroke Risk Score (0.03, P < 0.0001) and Totaled Health Risks in Vascular Events Score (0.07, P < 0.0001), and yielded continuous net reclassification improvement (19.0%, P < 0.0001; 33.0, P < 0.0001). CONCLUSIONS: In the patients with ischemic stroke or TIA, IL-6 and YKL-40 were independently associated with recurrent stroke and poor functional outcome, and improved risk classification of clinical risk algorithms.