Association of the remnant cholesterol inflammation index with long-term outcomes among patients with acute ischemic stroke treated with intravenous thrombolysis

Background The Remnant Cholesterol Inflammation Index (RCII) is a novel assessment tool that reflects lipid metabolism disorders and systemic inflammation, and may be associated with adverse vascular outcomes. This study aimed to investigate the relationship between RCII and long-term outcomes in patients with acute ischemic stroke (AIS) after intravenous thrombolysis (IVT). Methods We conducted a cohort study of 748 patients with AIS who received IVT between April 2019 and March 2025 and survived the index hospitalization. All patients were divided into four groups based on log-transformed RCII (lnRCII), and the endpoint events studied were recurrent ischemic stroke and all-cause mortality. Patients were followed from hospital discharge until March 31, 2026. We used survival and competing-risk analyses, Cox proportional hazards models, and restricted cubic splines to evaluate the associations between lnRCII and long-term outcomes. Results The median age was 68 years, the interquartile range was 59–76 years, 63.6% were male. During the follow-up period, recurrent ischemic stroke was confirmed in 101 (13.5%) patients, and all-cause mortality was confirmed in 120 (16.0%) patients. Multivariable Cox analysis showed that higher lnRCII levels were significantly associated with increased risks of recurrent ischemic stroke (HR = 1.373, 95% CI: 1.174-1.605, P < 0.001) and all-cause mortality (HR = 1.275, 95% CI: 1.107-1.469, P < 0.001). Restricted cubic spline analyses demonstrated no significant evidence of nonlinearity in the associations between lnRCII and either outcome (P for nonlinearity > 0.05). Sensitivity analyses yielded generally consistent findings. Exploratory subgroup analyses identified significant interactions with age and hypertension for all-cause mortality. Conclusions In patients with AIS treated with IVT, elevated RCII was independently associated with an increased risk of long-term recurrent ischemic stroke and all-cause mortality. RCII may prove to be a composite marker associated with long-term outcomes.