Validation of a prognostic subarachnoid hemorrhage grading scale derived directly from the Glasgow Coma Scale

Background and Purpose - A new Glasgow Coma Scale- based scale has been developed to predict patient outcome in subarachnoid hemorrhage by calculating cut- off points by which 2 consecutive categories corresponded to a statistically significant different outcome. We assessed the external validity of this Prognosis on Admission of Aneurysmal Subarachnoid Hemorrhage ( PAASH) scale and compared it to the commonly used World Federation of Neurological Surgeons scale. Methods - From our database of subarachnoid hemorrhage patients we retrieved data on all patients admitted between November 2000 and March 2006. By means of logistic regression, we calculated OR with corresponding 95% CI for poor outcome at 3 months for each category in comparison with the lowest category of both scales. Areas under the curve of the corresponding receiver operator characteristic curve were calculated. Results - We included 537 patients. For the PAASH scale, OR ranged from 3.9 ( 95% CI, 2.4 to 6.2) to 84 ( 95% CI, 25 to 287) and increased more evenly than for the World Federation of Neurological Surgeons ( WFNS) scale, with OR ranging from 2.3 ( 95% CI, 1.3 to 4.1) to 69 ( 95% CI, 31 to 157). Areas under the curve were 0.81 ( 95% CI, 0.77 to 0.84) for the PAASH and 0.82 ( 95% CI, 0.79 to 0.86) for the WFNS scale. Conclusion - Both PAASH and WFNS scales have a good discriminatory ability for patient prognosis. Because the OR of the PAASH increase more gradually, it is slightly preferable to the WFNS scale.