International Subarachnoid Trial in the Long Run

Abstract

Abstract The International Subarachnoid Trial (ISAT), the largest prospective randomized study into endovascular and neurosurgical treatment of ruptured intracranial aneurysms, recently reported long-term follow-up in The Lancet Neurology. In this cohort, the risk of death at 5 years was significantly lower in the coiled group, but the proportion of survivors who were independent was not statistically different between the groups, and rebleeding was higher in the coiled group. This article critically evaluates the long-term ISAT data from an evidence-based perspective and places it in the context of the overall approach to treatment of ruptured intracranial aneurysms. ISAT has been a strong driver of change in the management of ruptured aneurysms. Nevertheless, the evidence for the superiority in coiling in the long term should not be assumed from ISAT data alone. Potential biases of patient characteristics and national referral patterns, as well as the methodological problems already described from the original trial, contribute to the difficulty in interpreting differences in long-term outcomes. These new data should be regarded as Level 2b evidence, suitable for treatment recommendations but not guidelines.