Association of Endovascular Thrombectomy Volume and Outcomes in Acute Ischemic Stroke: A National Inpatient Sample Study

Background: Previous studies have reported a positive relationship between higher hospital endovascular thrombectomy (EVT) volume and shorter procedures, higher revascularization rates, and improved functional outcomes. We investigated the association between hospital EVT volume and clinical outcomes using the National Inpatient Sample (NIS) database from 2016-2020. Methods: A cross-sectional analysis of the NIS examining the relationship of hospital EVT volume and outcomes was performed. All relevant clinical and demographic information was collected. The outcomes were favorable functional outcome (home without assistance), inpatient mortality, and intracerebral hemorrhage (ICH). Centers were classified as high-volume if they were in the top quintile of annual EVT volume. We performed univariate, multivariate, nearest neighbor matched analysis, and an exploratory annual case volume cutoff analysis. Results: There were 114,640 patients who underwent EVT included in the sample. Of these, 24,415 (21.3%) were in the high-volume group. High-volume centers had higher rates of favorable functional outcome in univariate (OR 1.20, p < 0.001), multivariate (aOR 1.19, p = 0.003), and matched analysis (OR 1.14, p = 0.028). Prior to matching, lower rates of inpatient mortality (OR 0.83, p < 0.001). However, in univariate and matched analysis there were no differences between high and low-volume centers. There were no differences in ICH across all analyses. Functional benefit was first noted at [≥] 50 EVTs, but centers performing [≥] 175 EVTs had substantially higher functional benefit (aOR 1.42, p = 0.002). Conclusions: Our analysis demonstrates increased hospital case volume is associated with a modest improvement in favorable functional outcomes in patients undergoing EVT for AIS. Attempts to identify procedural cut off values reveal likely improved functional outcomes beginning at 50 EVT per year, while this benefit seems to increase with increasing case volumes. These higher levels of case volumes do not lead to higher rates of inpatient mortality or ICH. ?