Associations of nine composite inflammatory indices with clinical outcomes after mechanical thrombectomy for acute ischemic stroke: a single-center retrospective study

This study aims to explore the associations of nine common composite inflammatory indices with hemorrhagic transformation (HT), unfavorable outcome, and all-cause mortality in patients with acute ischemic stroke (AIS) following mechanical thrombectomy (MT).

A retrospective study was conducted with composite inflammatory indices, including systemic immune-inflammation index (SII), systemic inflammation response index, pan-immune-inflammation value, neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), lymphocyte-to-monocyte ratio, neutrophil-to-platelet ratio, C-reactive protein-to-lymphocyte ratio, and neutrophil percentage-to-albumin ratio. Blood sampling was performed before MT procedure. Unfavorable outcome was defined as modified Rankin Scale score > 2 at 90-day follow-up. Multivariable analyses were performed to explore the associations between composite inflammatory indices and clinical outcomes with false discovery rate (FDR) correction, and the continuous indices were standardized to z-scores. The SII, NLR and PLR, all of which showed consistent significant relationships with clinical outcomes, were subjected to further subgroup analyses.

There were 508 patients included, with age of 73 [interquartile range (IQR) 64-78], 233 (45.9%) female patients, and National Institutes of Health Stroke Scale score of 15 [IQR 12-19]. The SII, NLR and PLR, whether treated as continuous or categorical variable (classified into tertiles), were significantly associated with HT (SII: odds ratio [OR] 1.487, 95% confidence interval [CI] 1.206-1.843, p-FDR = 0.001; NLR: OR 1.592, 95% CI 1.292-1.977, p-FDR < 0.001; and PLR: OR 1.457, 95% CI 1.182-1.806, p-FDR = 0.001), unfavorable outcome (SII: OR 1.662, 95% CI 1.293-2.178, p-FDR < 0.001; NLR: OR 1.648, 95% CI 1.291-2.148, p-FDR < 0.001; and PLR: OR 1.707, 95% CI 1.319-2.267, p-FDR < 0.001) and all-cause mortality (SII: hazard ratio [HR] 1.392, 95% CI 1.218-1.591, p-FDR < 0.001; NLR: HR 1.284, 95% CI 1.111-1.484, p-FDR = 0.001; and PLR: HR 1.413, 95% CI 1.240-1.609, p-FDR < 0.001). Subgroup analyses revealed interactions of SII and NLR with mortality (p for interaction = 0.029 and 0.004, respectively), indicating particularly robust associations in patients with cardioembolic stroke.

The SII, NLR and PLR may serve as consistent biomarkers of post-MT HT, unfavorable outcomes and all-cause mortality. Closer monitoring may be required for cardioembolic stroke patients with elevated systemic inflammatory burden.