Patterns of Mechanical Thrombectomy for Stroke Before and After the 2015 Pivotal Trials and US National Guideline Update

Abstract

BackgroundPositive pivotal trials followed by guideline endorsement can be a major driver of change in US national medical practice patterns. We therefore analyzed national trends in the use and outcomes of mechanical thrombectomy for acute ischemic stroke due to large vessel occlusion before and after the 2015 publication of pivotal trials and the US guideline update. MethodsWe analyzed the National Inpatient Sample from 2012-2016. Ischemic stroke and mechanical thrombectomy patients were identified using ICD-9 and ICD-10. The primary efficacy outcome measure was discharge to home, which strongly correlates with mild degree of disability at discharge. Safety outcomes include in-hospital mortality and in-hospital medical complications. ResultsFrom 2012-2016, 2,394,550 discharges were recorded with a diagnosis of ischemic stroke, including 39,150 (1.6%) treated with mechanical thrombectomy. The number and proportion of stroke patients undergoing mechanical thrombectomy annually rose from 4,910/452,905 (1.1%) in 2012 to 11,860/509,215 (2.3%) in 2016. The largest annual increase occurred between 2014, when 6,460 stroke patients were treated with thrombectomy, and 2015, when 10,280 underwent thrombectomy. Comparing the pre (Q1 2012 - Q4 2014) and post (Q4 2015 – Q4 2016) RCT/Guideline epochs, in addition to increased thrombectomy rates, the proportion of thrombectomy patients who received IV-tPA decreased (46% to 24%, p<0.001). Rates of mild disability outcome increased from 16% to 20% (p<0.001), while mortality decreased from 15% to 13% (p=0.01). The odds of pulmonary embolism, urinary tract infection, and pneumonia decreased, while intracerebral hemorrhage, septicemia, deep venous thrombosis, shock, and cardiac arrest were unchanged. ConclusionIn the United States, thrombectomy treatment for acute ischemic stroke increased rapidly and substantially in frequency following publication of positive clinical trials and US guideline update in 2015, accompanied by improved functional outcomes and reduced peri-procedural mortality.