The Role of Thrombin Time as an Independent Variable in Predicting In-Stent Stenosis Risk After Flow Diverter Treatment for Intracranial Aneurysms: A Retrospective Cohort Study

Unruptured intracranial aneurysms are common neurovascular diseases, and flow diverters (FD) are emerging as a key treatment modality. However, in-stent stenosis (ISS) remains a frequent complication following FD treatment, increasing thromboembolic risks. Thrombin time (TT), a critical coagulation indicator, has potential associations with ISS risk. To investigate the relationship between TT and ISS risk, focusing on potential threshold effects. This multicenter retrospective cohort study included 394 patients with unruptured intracranial aneurysms treated with FD between March 2016 and October 2024. The primary exposure was preoperative TT, and the primary outcome was ISS occurrence during follow-up. Generalized additive models explored non-linear relationships, with segmented linear regression determining threshold points. ISS occurred in 22.84% (90/394) of patients. TT exhibited a non-linear relationship with ISS risk, with a threshold of 19.2 seconds. For TT values below this threshold, each unit increase was linked to a 59% higher likelihood of developing ISS (OR = 1.59, 95% CI: 1.19–2.13, p = 0.002). These findings may assist in identifying patients at greater risk for ISS who could benefit from more intensive intervention.