Disability-free outcomes after mechanical thrombectomy: A systematic review and meta-analysis of the randomized controlled trials

Background: The modified Rankin Scale (mRS) score of ≤2 (functional independence) has been the most common primary endpoint of modern mechanical thrombectomy (MT) trials. However, unlike mRS 0-1, mRS score of 2 indicates disability. An important proportion of the mRS 2 patients are home dependent and report a significant decrease in their quality of life. Purpose: To investigate excellent outcome (mRS 0-1) rates after MT. Methods: We systematically searched Ovid MEDLINE, Ovid EMBASE, Cochrane Central Register of Controlled Trials, Scopus, and Web of Science databases. Randomized controlled trials (RCTs) investigating the role of modern MT in acute ischemic stroke were screened. Posterior circulation and large-core infarct trials were excluded from the study. The data regarding excellent outcomes (mRS: 0-1), functional independence (mRS: 0-2), and reperfusion were collected. Results: Twenty-two RCTs comprising 5692 patients were included in the meta-analysis. The overall mRS 0-1 rate was 31.24% (95% CI = 26.95–36.2). The rate of successful reperfusion was 81.8% (95% CI = 77.93–85.86). MT achieved significantly higher rates of mRS 0-1 compared to standard care alone (OR = 2.04; 95% CI = 1.64–2.55; P-value < 0.001), with no heterogeneity detected among studies (I²= 0%; P-value = 0.52). The direct MT and MT plus intravenous thrombolytic treatment groups’ excellent outcome rates were comparable (OR = 0.98; 95% CI = 0.82–1.18; P-value = 0.863). Also, aspiration and stent retriever thrombectomy techniques provided similar excellent outcome rates (OR = 0.76; 95% CI = 0.55–1.05; P-value = 0.141). Conclusions: Our results prove the additional benefit of MT over standard care, using a stricter definition for favorable functional outcome. Nearly one-third of patients presenting with large artery occlusion and treated with MT had no disability at 90 days. While this is remarkable, our results also indicate that reperfusion alone is often not enough to prevent disability and underline the need for better neuroprotection strategies.