Early neurological improvement as a predictor of outcomes after endovascular thrombectomy for stroke: a systematic review and meta-analysis

Background Early neurological improvement (ENI) is a potential predictor for 90-day outcomes following mechanical thrombectomy for acute ischemic stroke (AIS). We performed a systematic review and meta-analysis to better understand whether ENI can be used as a surrogate for long-term outcomes following mechanical thrombectomy for AIS. Methods Following the PRISMA guidelines, a systematic literature review of the English language literature was conducted using PubMed, MEDLINE, and Embase. ENI definition, including timing and degree of improvement on the National Institutes of Health Stroke Scale (NIHSS), was catalogued for each included study. Outcomes of interest included 90-day modified Rankin Scale (mRS) 0–2, symptomatic intracranial hemorrhage (sICH), and mortality. We calculated pooled ORs and their corresponding 95% confidence intervals (CI) for all definitions of ENI. Results We included nine studies with 2355 patients in our analysis. ENI definitions included improvement in NIHSS of 8 points, 4 points, 12%, and 30% or greater. There was a significant association between ENI and mRS 0–2 rates (OR 8.62, 95% CI 4.86 to 15.29; p<0.001). Significance of the association was maintained across all definitions (p<0.001). Moreover, achieving ENI was a significant predictor of reduced odds for reported sICH rates (OR 0.11, 95% CI 0.06 to 0.21; p<0.001). There was a significant association between ENI and reduction in mortality rates (OR 0.09, 95% CI 0.05 to 0.15; p<0.001). Conclusions Broadly defined, ENI is a promising predictor of good functional outcome at 90 days and is associated with lower rates of mortality and sICH.