Grading of Subarachnoid Hemorrhage: Modification of the World Federation of Neurosurgical Societies Scale on the Basis of Data for a Large Series of Patients

OBJECTIVE: The goals of this study were to use a large, prospectively collected, multicenter database for patients with aneurysmal subarachnoid hemorrhage (SAH) who were treated between 1991 and 1997 to determine the prognostic significance of clinical and radiological factors for outcomes and to use those factors to develop a grading scale to predict outcomes. METHODS: A total of 3567 patients with SAH who were entered into four randomized clinical trials of tirilazad were studied. Outcomes were assessed 3 months after SAH, with the Glasgow Outcome Scale. Twenty clinical and radiological factors were entered into univariate and multivariate analyses, to determine factors prognostic for outcomes. Grading scales based on the most powerful prognostic parameters were statistically derived and validated and were compared with the World Federation of Neurosurgical Societies (WFNS) grading scale. RESULTS: Factors predictive of outcomes included age, WFNS grade, history of hypertension, systolic blood pressure at admission, ruptured aneurysm location and size, blood clot thickness on computed tomographic scans, and angiographic vasospasm at admission. A grading scale using these factors could be derived; it predicted outcomes more accurately than did the WFNS scale, although it would be more complex to use. CONCLUSION: Outcome prediction after SAH can be improved by adding additional clinical and radiological factors to the WFNS scale, albeit with added complexity.