Trends of Ruptured and Unruptured Aneurysms Treatment in the United States in Post‐ISAT Era: A National Inpatient Sample Analysis

BACKGROUND: The ISAT (International Subarachnoid Aneurysm Trial) has generated a paradigm shift towards endovascular treatment for intracranial aneurysms but remains unclear if this has led to a true reduction in the risk for aneurysmal subarachnoid hemorrhage (aSAH). We sought to study the association between the treatment burden of unruptured and ruptured aneurysms in the post‐ISAT era. METHODS AND RESULTS: Admissions data from the National Inpatient Sample (2004–2014) were extracted, including patients with a primary diagnosis of aSAH or unruptured intracranial aneurysms treated by clipping or coiling. Within each year, this combined group was randomly matched to non‐aneurysmal control group, based on age, sex, and Elixhauser comorbidity index. Multinomial regression was performed to calculate the relative risk ratio of undergoing treatment for either ruptured or unruptured aneurysms in comparison with the reference control group, adjusted for time. After adjusting for National Inpatient Sample sampling effects, 243 754 patients with aneurysm were identified, 174 580 (71.6%) were women; mean age, 55.4±13.2 years. A total of 121 882 (50.01%) patients were treated for unruptured aneurysms, 79 627 (65.3%) endovascularly and 42 256 (34.7%) surgically. A total of 121 872 (49.99%) patients underwent procedures for aSAH, 68 921 (56.6%) endovascular, and 52 951 (43.5%) surgically. Multinomial regression revealed a significant year‐to‐year decrease in aSAH procedures compared with the control group of non‐aneurysmal hospitalizations (relative risk ratio, 0.963 per year; P<0.001), while there was no statistical significance for unruptured aneurysms procedures (relative risk ratio, 1.012 per year; P=0.35). CONCLUSIONS: With each passing year, there is a significant decrease in relative risk ratio of undergoing treatment for aSAH, concomitant with a stable annual risk of undergoing treatment for unruptured intracranial aneurysms.