Background and Purpose-The International Subarachnoid Aneurysm Trial (ISAT) reported lower rates of death and disability with endovascular versus neurosurgical treatment of ruptured intracranial aneurysms. However, assessment of functional outcome was limited to the modified Rankin Scale, which is known to be insensitive to cognitive function. A neuropsychological substudy (N-ISAT) was therefore done in all recruits from 8 ISAT centers in the United Kingdom. Methods-Detailed neuropsychological assessment was performed at a 12-month follow-up visit. Impairment was defined as performance below the 5th percentile of the study population on at least 2 tests in Ն2 major cognitive domains. Analysis was restricted to patients who were not known to be otherwise disabled according to the modified Rankin Scale (ie, modified Rankin Scale 0 to 2). initially reported the primary clinical outcomes on the modified Rankin Scale (mRS) at 2 months and 1 year after neurosurgical clipping or endovascular coiling as a treatment for ruptured intracranial aneurysms. 1,2 Unfavorable outcomes at 12 months (ie, mRS Grade 3 to 6) were reported in 30.9% of cases randomized to neurosurgery and 23.5% to embolization with a difference in mortality still evident at 5-year follow-up. 3 However, clinical disability and handicap scales such as the mRS are insensitive to poor neuropsychological outcomes, 4,5 and the effect of endovascular versus neurosurgical treatment on cognitive outcomes in patients without physical disability is uncertain. Previous small studies have identified clinically significant neuropsychological impairments with an impact on overall quality of life in patients with an apparently "good" neurological outcome (ie, Glasgow Outcome Scale Grade 1) after subarachnoid hemorrhage (SAH). [5][6][7] The ISAT protocol therefore included a substudy (N-ISAT) in which detailed neuropsychological assessments at 12-month follow-up were performed in all patients randomized from 8 UK centers. We report the rates of cognitive impairment in patients who had no major physical disability (mRS 0 to 2) to
Results-Of
MethodsThe eligibility, recruitment, and characteristics of ISAT, from which the N-ISAT subsample was drawn, have been reported together with the main trial design and methods. 1 The detailed methods of N-ISAT in terms of organization, training, recruitment, and assessment protocols have also been reported together with an analysis of data quality. 8,9 The study was approved by the Oxford Research Ethics Committee. All patients who had been enrolled in the 8 UK centers participating in N-ISAT and who had survived to 12 months were followed-up as per the main ISAT protocol 1 and were also eligible for face-to-face neuropsychological assessment as part of N-ISAT. Patients were contacted by letter followed by a telephone call initially. Multiple attempts were made to contact nonresponders. 9 Given the uncertainty about the number of cases that would be randomized in the United Kingdom, the pragmatic aim was to study all randomized cas...