Optimal 24-h NIHSS threshold of ⩽9 predicts 90-day outcomes after posterior circulation thrombectomy: ANGEL-ACT Registry Insights.

Background: In patients with posterior circulation stroke, the association between National Institutes of Health Stroke Scale (NIHSS) scores after thrombectomy and 90-day functional outcomes remains unclear.

Objectives: We aimed to explore which factors among the 24-h NIHSS score, ΔNIHSS (baseline NIHSS minus 24-h NIHSS), and NIHSS score change rate (ΔNIHSS/baseline NIHSS × 100%) are associated with favorable functional outcomes at 90 days postoperatively in patients with posterior circulation stroke.

Design: We performed a post hoc analysis of a prospective observational study utilizing key techniques of endovascular treatment and emergency workflow improvements from the acute ischemic stroke registry. The study included a cohort of 353 patients who underwent thrombectomy due to posterior circulation stroke. For all patients, we collected baseline characteristics, lesion locations, NIHSS scores, ΔNIHSS (baseline NIHSS minus 24-h NIHSS), NIHSS score change rate (ΔNIHSS/baseline NIHSS × 100), and 90-day postoperative modified Rankin Scale (mRS) score.

Methods: A 90-day postoperative mRS score of 0-2 was defined as a favorable functional outcome, while a score of 3-6 was defined as an unfavorable functional outcome. The 24-h NIHSS score and ΔNIHSS score were converted into binary variables based on the Youden index to determine the optimal thresholds that best predict favorable functional outcomes at 90 days postoperatively. Adjusted logistic regression analysis was used to assess the predictive efficacy of the 24-h NIHSS score, ΔNIHSS (baseline NIHSS minus 24-h NIHSS), and NIHSS score change rate (ΔNIHSS/baseline NIHSS × 100) for the 90-day mRS. Subsequently, patients were categorized into cardioembolic embolism (CE) and large artery atherosclerosis (LAA) subgroups according to the Trial of Org 10172 in Acute Stroke Treatment classification, and the predictive efficacy of the optimal thresholds was examined within these subgroups.

Results: Multivariate logistic regression analysis revealed that the 24-h NIHSS score was an independent predictor of 90-day functional outcomes (odds ratio (OR): 10.61, 95% confidence interval: 6.44-17.46, p < 0.001). The Youden index identified a 24-h NIHSS score of ⩽9 as the threshold for predicting an mRS score of 0-2, demonstrating good sensitivity (78.5%) and specificity (76.3%). The receiver operating characteristic curve indicated that the predictive model had good discriminative ability (area under the ROC curve = 0.8223). In subgroup analysis, a 24-h NIHSS score of ⩽9 also showed superior predictive efficacy in both the CE (sensitivity 67.8%, specificity 73.5%) and LAA (sensitivity 81.1%, specificity 74.4%) groups.

Conclusion: The 24-h postoperative NIHSS score is a reliable predictor of 90-day functional outcomes in patients with posterior circulation stroke undergoing endovascular treatment. The predictive efficacy is optimal when the NIHSS score is ⩽9.