Impact of Herniation on WFNS Grading in Spontaneous Subarachnoid Hemorrhage - a SWISS SOS Observational Trial

Plain-language summary

All patients (≥18 years) with a spontaneous SAH proven by computed tomography (CT), magnetic resonance imaging (MRI) or lumbar puncture will be considered for this trial. Upon presentation to a neurosurgical centre the patients will be treated according to the local protocol. Upon admission the patient is clinically evaluated for occurrence of clinical signs of brain herniation syndromes (anisocoria, bilateral dilated pupils, posturing). Usually first line treatment includes neurological resuscitation (placement external cerebrospinal fluid drainage in case of hydrocephalus, treatment of seizure, and general intensive care measures). Hereafter, the patient is clinically evaluated for a second time. The patients will be graded according to the usual WFNS scale and the modified "herniation WFNS" scale. The whole treatment of the patient will be according to local clinical protocols. Outcome will be measured at six and twelve months by trained investigators who are unaware of clinical data. The primary endpoint is the difference of specificities of the WFNS and hWFNS with respect to poor outcome (mRS 4-6) at 6 months after initial haemorrhage. Given that specificity and sensitivity are negatively correlated, difference in sensitivity will be the second primary outcome. The null hypothesis to be tested is that the ratio of the true negative rates (specificity) of the hWFNS and WFNS scores is 1.35 i.e. the new score will detect 35% more patients as truly negative (good outcome) as compared to the old score. In addition and because of the negative correlation between specificity and sensitivity we will also test that the ratio of the true positive rate (sensitivity) is not below 0.82 i.e. the new score will not more than 18% less patients as truly positive (poor outcome).

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