BackgroundThrombospondin-1 is a homotrimeric glycoprotein with well known functions in hemostasis and angiogenesis. Its expression was increased after experimental intracerebral hemorrhage. We determined whether increased plasma thrombospondin-1 concentrations are predictive of clinical outcomes of aneurysmal subarachnoid hemorrhage (aSAH). MethodsPlasma thrombospondin-1 concentrations of 118 aSAH patients and 118 age- and gender-matched healthy controls were determined using enzyme-linked immunosorbent assay. Patients were followed up until death or completion of 6months after aSAH. An unfavorable outcome was defined as Glasgow Outcome Scale score of 1–3. Multivariate analyses of significant variables of univariate analyses were performed to determine independent risk factors for the clinical outcomes. ResultsPlasma thrombospondin-1 concentrations were significantly higher in aSAH patients than in healthy controls; plasma thrombospondin-1 concentrations were independently associated with clinical severity reflected by the World Federation of Neurological Surgeons score and Fisher score; thrombospondin-1 was identified as an independent predictor of 6-month mortality and 6-month unfavorable outcome; thrombospondin-1 had similar predictive performance compared with the World Federation of Neurological Surgeons score and Fisher score according to receiver operating characteristic curve analysis. ConclusionHigher plasma thrombospondin-1 concentrations are associated with clinical severity and long-term prognosis of aSAH patients.