A new subarachnoid hemorrhage grading system based on the Glasgow Coma Scale: a comparison with the Hunt and Hess and World Federation of Neurological Surgeons Scales in a clinical series.

ABSTRACT

OBJECTIVE: Although the Hunt and Hess Scale (HHS) and World Federation of Neurological Surgeons Scale (WFNSS) are the most widely used subarachnoid hemorrhage (SAH) grading systems, neither system has achieved universal acceptance. We propose a simplified grading system based entirely on the Glasgow Coma Scale (GCS), which compresses the 15-point GCS into five grades that are comparable with those of the HHS and WFNSS. We refer to this system as the GCS grading system and present a direct comparison with the HHS and WFNSS for predictive value regarding patient outcome and interrater reliability. METHODS: We reviewed 291 consecutive patients with aneurysms treated at our institution between January 1992 and January 1996 and compared the admission grades from the GCS, WFNSS, and HHS with outcome measures at discharge from hospitalization. The Glasgow Outcome score was used as the major outcome measure to evaluate the predictive value of the three scales. Mortality and length of stay (LOS) were also evaluated as outcome measures. The predictive value of each scale was tested with an ordinal logistic regression model for Glasgow Outcome score, a logistic regression model for mortality data, and a linear regression model for LOS. RESULTS: Using the logistic regression model, the GCS was the best predictor of discharge Glasgow Outcome score, with an odds ratio of 2.585 (P = 0.0001), compared with 2.311 (P = 0.0001) for the WFNSS and 2.262 (P = 0.0001) for the HHS. Using mortality data in the logistic model, the HHS was the best predictor, with an odds ratio of 3.391 (P = 0.0001), compared with 2.859 (P = 0.0001) for the GCS and 2.560 (P = 0.0001) for the WFNSS. Each of the three scales had a high predictive value for LOS, using a linear model. We discuss, however, the problematic nature of LOS as an outcome measure for SAH. Interrater reliability for each scale was evaluated using kappa statistics, based on 15 additional patients evaluated prospectively, and showed that the GCS grade also had the greatest interrater reliability, with a kappa of 0.46 (P = 0.0002), compared with 0.41 (P = 0.0005) for the HHS and 0.27 (P = 0.027) for the WFNSS. CONCLUSION: We conclude that the GCS grade has equal or greater predictive value regarding outcome after SAH than do the currently used grading systems and that it has greater reproducibility across observers. Broader familiarity with the GCS among medical and paramedical personnel may further enhance the usefulness of the GCS grade over the HHS and WFNSS in providing a standardized, universally accepted grading system for SAH.