Prognostic and clinicopathological impacts of systemic immune-inflammation index on patients with diffuse large B-cell lymphoma: a meta-analysis

Background: The systemic immune-inflammation index (SII) represents the immunoinflammatory score and can be considered as a prognostic marker; however, its relevance to the prognosis in patients with diffuse large B-cell lymphoma (DLBCL) remains unclear.Objectives: The present meta-analysis was conducted to comprehensively evaluate the relationship between the SII and prognosis in patients with DLBCL.Design: This meta-analysis was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement.Data sources and methods: The PubMed, Web of Science, Embase, and Cochrane Library databases were comprehensively searched from inception to 16 March 2023. We calculated combined hazard ratios (HRs) and 95% confidence intervals (CIs) to estimate the prognostic significance of the SII for overall survival (OS) and progression-free survival (PFS) in DLBCL. In addition, this study determined odds ratios (ORs) and their 95% CIs to evaluate the correlation of SII with the clinicopathological features of DLBCL.Results: Five articles including 592 cases were enrolled in the current meta-analysis. According to our combined findings, the higher SII significantly predicted worse OS (HR = 3.87, 95% CI: 2.48-6.04, p < 0.001) together with inferior PFS (HR = 2.38, 95% CI: 1.12-5.08, p = 0.024) in DLBCL. Furthermore, a high SII was significantly correlated with B symptoms (OR = 2.52, 95% CI: 1.66-3.81, p < 0.001), III-IV Ann Arbor stage (OR = 2.86, 95% CI: 1.84-4.45, p < 0.001), high-intermediate/high National Comprehensive Cancer Network International Prognostic Index (OR = 2.25, 95% CI: 1.52-3.31, p < 0.001), increased neutrophil-to-lymphocyte ratio (OR = 33.76, 95% CI: 17.18-66.35, p < 0.001), and increased platelet-to-lymphocyte ratio (OR = 44.65, 95% CI: 5.80-343.59, p < 0.001). Nonetheless, the SII was not significantly related to sex, age, lactic dehydrogenase level, Eastern Cooperative Oncology Group performance status, or histology.Conclusion: According to this meta-analysis, the higher SII dramatically predicted inferior OS and PFS of DLBCL. Furthermore, an increased SII significantly correlated with some clinicopathological features representing the disease progression of DLBCL.Trial registration: The protocol was registered in INPLASY under the number INPLASY202380106.