Revisiting the WFNS Score: Native Computed Tomography Imaging Improves Identification of Patients With “False Poor Grade” Aneurysmal Subarachnoid Hemorrhage

Abstract

BACKGROUND AND OBJECTIVES: In patients suffering from aneurysmal subarachnoid hemorrhage (aSAH), the optimal time to determine the World Federation of Neurosurgical Societies (WFNS) score remains controversial because of possible confounding factors. Goals of this study were (1) to analyze the most sensitive timepoint to determine the WFNS score in patients with aSAH and (2) to evaluate the impact of initial native computed tomography (CT) imaging on reducing the mismatch of “false poor grade” patients. METHODS: We retrospectively analyzed daily WFNS scores from admission until day 7 in 535 aSAH patients and evaluated their predictive value for the modified Rankin Scale at discharge and 6 months postbleeding. Patients with an initial WFNS score of IV–V who showed improvement to a WFNS score of I–II within the first 7 days (even short-term) were defined as “false poor grade” patients. We tried to identify the “false poor grade” patients using parameters of the initial native CT imaging. RESULTS: Later determination of the WFNS score (day 1 vs 7; pseudo-R2 = 0.13 vs 0.21) increasingly improved its predictive value for neurological outcome at discharge (P < .001). We identified 39 “false poor grade” patients who had significantly better outcomes than “real poor grade” patients (N = 220) (modified Rankin Scale-discharge: 0-2, 56% vs 1%, P < .001; 3-5: 41% vs 56%, P = .12; 6: 3% vs 43%, P < .001). “False poor grade” patients differed significantly in initial CT parameters. A predictive model called “initial CT WFNS” (ICTWFNS) was developed, incorporating SEBES, Hijdra score, and LeRoux score (sensitivity = 0.95, specificity = 0.84, accuracy = 0.859, F1 = 0.673). ICTWFNS scores of ≤4.6 classified patients as “false poor grade.” CONCLUSION: The initial WFNS score may misclassify a subgroup of patients with aSAH as poor grade, which can be avoided by later determination of the WFNS score, at days 3–4 losing its usefulness. Alternatively, the initial WFNS score can be improved in its predictive value, especially in poor-grade patients, using criteria from the initial native CT imaging, such as the Hijdra, LeRoux, and Subarachnoid Hemorrhage Early Brain Edema score, combined in the ICTWFNS score with even higher predictive power.