Predictive value of the systemic immune-inflammation index for periprocedural complications in flow diverter treatment for patients with intracranial aneurysms.

Flow-diverter devices (FDs) are effective in treating intracranial aneurysms (IAs) but carry substantial periprocedural risks, particularly ischemic complications. This study aimed to determine if elevated Systemic Immune-Inflammation Index (SII) can independently predict these risks and assess the impact of age and dual antiplatelet therapy on this association. We conducted a retrospective analysis of patients treated with FDs between February 2016 and August 2023, using blood samples taken within six days before surgery to calculate SII. Logistic regression and decision tree analyses assessed the link between SII and periprocedural complications, with subgroups exploring influencing factors. Multivariable analysis identified high SII as an independent predictor of periprocedural complications (OR = 5.306, 95% CI: 1.367-18.455; P = 0.009). The decision tree model confirmed SII > 0.437 as a critical threshold. Subgroup analysis showed a pronounced association of SII with periprocedural complications in patients ≥ 65 years (OR = 36.979, 95% CI: 2.103-650.134; P = 0.014) and in those on clopidogrel plus aspirin therapy (OR = 16.921, 95% CI: 2.733-104.746; P = 0.002). An elevated Systemic Immune-Inflammation Index (SII) > 0.437 significantly correlates with increased periprocedural complications (6.5% vs. 1.8%, P = 0.017). Although not statistically significant, higher SII is associated with a greater rate of ischemic events (3.9% vs. 0.9%). Elevated preoperative SII independently predicts periprocedural complications, particularly ischemic events, in patients undergoing FDs treatment for intracranial aneurysms. This association is particularly pronounced in older patients (> 65 years) and those receiving dual therapy with clopidogrel plus aspirin. Trial Registration: ClinicalTrials.gov (NCT06446778). Registered on May 22, 2024.