Admission systemic inflammatory indices and 6-month functional outcome after endovascular thrombectomy for acute ischemic stroke: an exploratory single-center cohort study
TL;DR
Admission NLR, SII, and SIRI are associated with 6-month poor outcome after EVT, but this association is largely explained by stroke severity, with no detectable incremental value beyond the National Institutes of Health Stroke Scale.
Abstract
Background Many patients still have poor functional outcomes after endovascular thrombectomy (EVT) for acute ischemic stroke. Systemic inflammatory indices from routine blood tests have been proposed as accessible prognostic biomarkers. We evaluated the association of admission neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), systemic immune-inflammation index (SII), and systemic inflammation response index (SIRI) with 6-month functional outcome after EVT, and tested whether they provide incremental prognostic value beyond the National Institutes of Health Stroke Scale (NIHSS). Methods We retrospectively analyzed consecutive patients undergoing EVT for anterior circulation acute ischemic stroke at one center. The primary outcome was poor functional outcome (modified Rankin Scale [mRS] 4–6) at 6 months. Associations were assessed with logistic regression and ROC analysis. Incremental value over NIHSS was assessed with likelihood-ratio tests, AUC comparison (DeLong), reclassification metrics (NRI, IDI), and decision-curve analysis. Results Of 90 patients, 82 (91.1%) completed follow-up, of whom 40 (48.8%) had poor outcomes; regression used 75 patients with complete inflammatory-index data (35 events). At the univariable level, poor outcome was associated with higher NIHSS (median 15.5 vs. 8.0, p < 0.001), NLR, SII, and SIRI (all p < 0.05). In multivariable analysis, only age was independently associated with poor outcome (OR 1.09, 95% CI 1.02–1.16, p = 0.008); the inflammatory indices were not, reflecting strong collinearity with NIHSS (rs = 0.88). NIHSS showed the highest discrimination (AUC 0.754, 95% CI 0.636–0.858), followed by SII (0.716, 0.592–0.836) and NLR (0.695, 0.570–0.808). Adding any inflammatory index to NIHSS did not improve discrimination or reclassification (likelihood-ratio p ≥ 0.40; ΔAUC ≤ 0.006; IDI ≈ 0; no meaningful net benefit), and results were unchanged under multiple imputation, though the sample could not exclude a small effect. Conclusion Admission NLR, SII, and SIRI are associated with 6-month poor outcome after EVT, but this association is largely explained by stroke severity, with no detectable incremental value beyond NIHSS. These exploratory findings are hypothesis-generating and require prospective multicenter validation before clinical use.