1153. National Trends in Cerebral Bypass for Unruptured Intracranial Aneurysms: A Nationwide Inpatient Sample Analysis of 1998-2015

Authors: Mayur Sharma, MD, MBBS; Beatrice Ugiliweneza; Enzo Fortuny, MD; Nicolas Khattar, MD; Noberto Andaluz, MD; Robert James, MD; Brian Williams, MD; Maxwell Boakye; Dale Ding, MD (Louisville, KY)

Introduction: The aim of this retrospective cohort study is to observe trends in cerebral revascularization procedures for unruptured intracranial aneurysms (UIAs) in the United States before and after the introduction of flow diverters using the Nationwide Inpatient Sample (NIS). Methods: We extracted data from the NIS database from 1998-2015 using ICD-9/10 codes. Patients with a primary diagnosis of UIA with a concurrent procedure of bypass were included. Outcomes and hospital charges were analyzed. Results: A total of 216,213 patients had a primary diagnosis of UIA. The number of patients increased by 128% from 1998 (n=7,718) to 2015 (n=17,600). Only 1,328 patients (0.6%) underwent cerebral bypass. The percentage of patients undergoing bypass in the flow diverter era (2010-2015) remained stable at 0.4%. Most patients were Caucasian (51%), female (62%), had a median household income in the 3 rd or 4 th quartiles (57%), and had private insurance (51%). The West (33%) and Midwest/North Central regions (30%) had the highest volume of bypasses, whereas the northeast had the lowest volume (15%). When compared to 1998-2011, bypass procedures for UIAs from 2012-2015 shifted entirely to urban teaching hospitals (100%) and on an elective basis (77%). The median length of hospital stay (9 vs. 3 days; p< 0.0001), median hospital charges ($186,746 vs. 66,361; p< 0.0001), and rate of any complication (51% vs. 17%; p<0.0001) were approximately threefold higher for UIA patients treated with versus without bypass. Conclusion: Despite a significant increase in the diagnosis of UIAs over the 17-year study period, the proportion of bypass procedures performed, has remained stable. Therefore, advances in endovascular aneurysm therapy do not appear to have affected the volume of bypass procedures performed in the study population. Our findings suggest a potentially ongoing niche for bypass procedures in the contemporary treatment of UIAs.