Similar safety in centers with low and high volumes of endovascular treatments for unruptured intracranial aneurysms: evaluation of the analysis of treatment by endovascular approach of nonruptured aneurysms study.

BACKGROUND AND PURPOSE The outcome of treatment for unruptured intracranial aneurysm by surgery or endovascular therapy appeared to be related to the volume of patients treated by the hospital. We performed an analysis in the ATENA series to determine whether the outcome of endovascular treatment was different in hospitals with low and high volumes of cases. MATERIALS AND METHODS The ATENA series included 649 patients with 739 unruptured intracranial aneurysms. Patients were classified into 2 groups. Group A had 171 patients with 197 aneurysms in 13 centers that treated < or =20 patients; group B, 478 patients with 542 aneurysms in 14 centers that treated > or =21 patients. RESULTS Groups A and B had similar patient populations and aneurysm characteristics. Stent placement was used in group B more frequently than in group A (9.6% versus 2.5%, P = .0016). The global rate of adverse events was not significantly different in groups A and B (16.0% and 14.4%, respectively). Thromboembolic events and intraoperative rupture were not significantly more frequent in group A than in group B. One-month mortality and morbidity rates were not significantly different in groups A (2.3% and 1.8%, respectively) and B (1.0% and 1.7%, respectively). Anatomic outcomes for groups A and B were not significantly different. CONCLUSIONS Clinical and anatomic outcomes of endovascular treatments for unruptured intracranial aneurysms were similar in hospitals with low and high volumes of cases.