High SII at admission linked to 2.14-fold increased risk of post-stroke depression

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Frontiers in Medicine Published June 5, 2026 Medically reviewed June 5, 2026 DOI ↗ By Dr. Ji-eun Park, MD · Brain, Mind & Pain

Key Takeaway

Consider using SII at admission as a biomarker to identify stroke patients at higher risk for post-stroke depression.

This meta-analysis pooled data from 2,780 adult stroke patients across multiple studies to evaluate the association between the systemic immune-inflammation index (SII) at admission and the risk of post-stroke depression (PSD). The primary outcome was the development of PSD, which occurred in 822 patients. The analysis found that a high SII was significantly associated with an increased risk of PSD, with a pooled odds ratio of 2.14 (95% CI: 1.74–2.64; I² = 22%). The authors note that the association remained consistent across study design, stroke type, age, sex proportion, SII cutoff method, cutoff value, PSD assessment tool, and study quality. Limitations include the observational nature of the included studies, which precludes causal inference, and the lack of reported follow-up duration and adverse events. The authors suggest that SII may serve as a simple and accessible inflammatory biomarker for early identification of patients at higher risk of developing PSD, though further prospective studies are needed to validate this finding.

Study Details

Study typeMeta analysis

EvidenceLevel 1

PublishedJun 2026

View Original Abstract ↓

BackgroundPost-stroke depression (PSD) is a common neuropsychiatric complication that adversely affects recovery and prognosis after stroke. The systemic immune-inflammation index (SII), a composite biomarker derived from peripheral blood counts, reflects systemic inflammatory status and has been associated with adverse neurological outcomes. However, the relationship between SII and PSD remains uncertain. We conducted a meta-analysis to clarify this association.MethodsPubMed, Embase, Web of Science, Wanfang, and CNKI were searched for observational studies evaluating the association between SII and PSD in adult stroke patients. Odds ratios (ORs) with 95% confidence intervals (CIs) were pooled using a random-effects model by incorporating the potential influence of heterogeneity.ResultsSeven studies involving 2,780 patients were included, among whom 822 developed PSD. Compared with lower SII levels, high SII at admission was significantly associated with an increased risk of PSD (OR = 2.14, 95% CI: 1.74–2.64; I² = 22%). Sensitivity analyses by excluding one study at a time showed similar results (pooled OR range: 2.06–2.38, all p-values < 0.05), which confirmed the stability of the findings. The association remained consistent across study design, stroke type, age, sex proportion, SII cutoff method, cutoff value, PSD assessment tool, and study quality (all p for subgroup differences > 0.05).ConclusionsElevated SII may be independently associated with an approximately twofold increased risk of PSD. SII may serve as a simple and accessible inflammatory biomarker for early identification of patients at higher risk of developing PSD.Systematic Review Registrationhttps://www.crd.york.ac.uk/prospero/, identifier CRD420261326749.