Increased serum interleukin-33 concentrations predict worse prognosis of aneurysmal subarachnoid hemorrhage

Abstract Background Interleukin-33 (IL-33) is an inflammatory biomarker. We elucidated the relationship between serum IL-33 concentrations, severity and prognosis in aneurysmal subarachnoid hemorrhage (aSAH). Methods We prospectively recruited 175 controls and 175 aSAH patients. Serum IL-33 concentrations were gauged using an enzyme-linked immunosorbent assay. Clinical and radiological severity was assessed by World Federation of Neurological Surgeons (WFNS) scale and modified Fisher grading scale respectively. Poor outcome was defined as Glasgow Outcome Scale score of 1–3. Results Serum IL-33 concentrations were significantly higher in patients than in controls. IL-33 concentrations were significantly increased with increasing WFNS scores, modified Fisher scores and serum C-reactive protein concentrations. Serum IL-33 emerged as an independent predictor for 6-month mortality and poor outcome. Under receiver operating characteristic curve, the prognostic predictive ability of serum IL-33 was equivalent to those of WFNS scores and modified Fisher scores. Moreover, serum IL-33 significantly improved the prognostic predictive performance of WFNS scores and modified Fisher scores. Conclusions High serum IL-33 concentrations have close relation to the inflammation, severity and poor outcome in aSAH, indicating IL-33 might have the potential to be an inflammatory biomarker for assessing severity and reflecting prognosis of aSAH.