Background: Delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (aSAH) is a significant cause of morbidity and mortality. While it is important to detect early signs of DCI, patients with high risk of DCI are difficult to identify, and the potential risk factors are uncertain. This study aimed to identify independent risk factors of DCI and clarify their clinical impact on outcome and the disease course. Methods: For this nationwide, multicenter, prospective clinical study involving consecutive patients with aSAH recruited from the China National Stroke Registry, demographic, clinical, radiological, and laboratorial data during hospitalisation, in-hospital complications, functional outcomes, and mortality at 3, 6, and 12 months were recorded. Using univariate and multivariate logistic regression to determine risk factors associated with the development of DCI, the contribution of DCI to short- and long-term outcomes was evaluated. Results: Of all 504 patients with aSAH, 155 developed DCI. Multivariate analysis revealed that being female, a history of diabetes mellitus, a Hunt and Hess grade of 4-5, and a World Federation of Neurosurgical Societies grade of IV-V were independent risk factors of DCI. DCI was associated with high in-hospital complications, and with a high utilization rate of supporting interventions. DCI also contributed to poorer functional outcome and higher mortality at discharge and after 3, 6, and 12 months. Conclusions: Female sex, a history of diabetes mellitus, and poor clinical grade are independent early risk factors for the development of DCI and can contribute to a better identification of patients at a high risk for DCI. DCI was associated with severe clinical course, poor outcome, and mortality both in the short- and long-term in patients with aSAH in China. (C) 2018 S. Karger AG, Basel