Mechanical thrombectomy in acute stroke: utilization variances and impact of procedural volume on inpatient mortality

Abstract

Background: An increasing number of endovascular mechanical thrombectomy procedures are being performed for the treatment of acute ischemic stroke. This study examines variances in the allocation of these procedures in the United States at the hospital level. We investigate operative volume across centers performing mechanical revascularization and establish that procedural volume is independently associated with inpatient mortality.

Methods: Data was collected using the Nationwide Inpatient Sample database in the United States for 2008. Medical centers performing mechanical thrombectomy were identified using International Classification of Diseases, 9th revision codes, and procedural volumes were evaluated according to hospital size, location, control/ownership, geographic characteristics, and teaching status. Inpatient mortality was compared for hospitals performing ≥10 mechanical thrombectomy procedures versus those performing<10 procedures annually. After univariate analysis identified the factors that were significantly related to mortality, multivariable logistic regression was performed to compare mortality outcome by hospital procedure volume independent of covariates.

Results: Significant allocation differences existed for mechanical thrombectomy procedures according to hospital size (P<.001), location (P<.0001), control/ownership (P<.0001), geography (P<.05), and teaching status (P<.0001). Substantial procedural volume was independently associated with decreased mortality (P=.0002; odds ratio 0.49) when adjusting for demographic covariates.

Conclusions: The number of mechanical thrombectomy procedures performed nationally remains relatively low, with a disproportionate distribution of neurointerventional centers in high-volume, urban teaching hospitals. Procedural volume is associated with mortality in facilities performing mechanical thrombectomy for acute ischemic stroke patients. These results suggest a potential benefit for treatment centralization to facilities with substantial operative volume.

Keywords: Acute stroke; mortality; neurointerventional procedures; thrombectomy.

Figure 1

Procedural volume by hospital. (A) Scatterplot demonstrating frequency of patients treated with endovascular mechanical revascularization at represented hospitals and (B) Histogram demonstrating percentage of hospitals performing mechanical thrombectomy by procedural volume. A natural segregation between centers performing ≥10 procedures (substantial volume) and those performing <10 procedures was derived from scatterplot results. Total substantial volume centers (≥ 10 patients treated/year) 78 (26.4%) and total lower volume centers were 218 (73.6%)