Abstract: Objective To evaluate the predictive value of systemic immune inflammatory index(SII) on hemorrhage transformation(HT) after intravenous thrombolysis(IVT) in the elderly patients with acute ischemic stroke(AIS). Methods A total of 347 elderly patients with AIS undergoing IVT in our hospital from August 2019 to February 2022 were retrospectively collected. They were divided into HT group and NHT group according to whether there was bleeding after thrombolysis, and the clinical data of the two groups were compared. SII value was calculated and the patients were divided into high SII group and low SII group according to the best cut-off value of ROC curve. Logistic regression was used to explore the risk factors of HT. The short-term functional prognosis of the elderly patients with AIS after IVT was evaluated by the modified Rankin scale(mRS), and the relationship between SII and functional prognosis was evaluated by the restricted cubic spline (RCS) model. Results There were 52 cases(15%) with HT. The value of SII in HT group was significantly higher than that in NHT group [1000.56(651.68,1531.38) vs 508.80(338.49,793.41), P<0.001]. The rate of poor short-term prognosis in high SII group was higher than that in low SII group(P<0.001). RCS showed a dose-dependent relationship between short-term poor prognosis and SII. Logistic regression showed that SII was independently associated with HT. Compared with low SII group, the risk of HT in high SII group increased by 6.65 times. ROC curve showed that when the value of SII was 721, the predictive value on HT in the elderly patients with AIS was the highest [AUC = 0.784(95% CI: 0.715-0.853), P<0.001]. Conclusions SII increases the risk of HT in the elderly patients with AIS after IVT, and is associated with poor short-term functional prognosis.

Key words: systemic immune inflammation index, acute ischemic stroke, intravenous thrombolytic, hemorrhagic transformation