Systemic immune-inflammation index and systemic inflammation response index: novel hematological predictors of...

While the association between obstructive sleep apnea (OSA) and chronic inflammation is well-established, the role of novel hematological indices, such as the systemic immune-inflammation index (SII) and systemic inflammation response index (SIRI), remains unclear. Their specific relationship with OSA has not been fully elucidated.

A total of 590 consecutive patients with suspected OSA were enrolled between June 2023 and August 2025. OSA was defined as an apnea-hypopnea index (AHI) of ≥5 events per hour. Spearman's rank correlation analysis was used to assess the relationships among SII, SIRI, AHI, and the lowest SpO₂. Logistic regression analyses were performed to examine the associations of SII and SIRI with OSA. Sensitivity analyses were conducted to evaluate the robustness of the findings. Receiver operating characteristic (ROC) curves were generated to assess the discriminative ability of SII and SIRI in identifying patients with OSA.

Of the 590 patients included in the study, 413 (70%) were diagnosed with OSA. Spearman rank correlation analysis revealed that both SII (r = 0.541, p < 0.001) and SIRI (r = 0.412, p < 0.001) were positively correlated with AHI. Conversely, SII (r = -0.470, p < 0.001) and SIRI (r = -0.374, p < 0.001) were inversely correlated with the lowest SpO₂. Binary logistic regression identified both SII (odds ratio [OR] = 1.601; 95% CI: 1.352-1.987; p < 0.001) and SIRI (OR = 1.459; 95% CI: 1.182-1.750; p < 0.001) as independent risk factors for OSA. The area under the curve (AUC) values for predicting OSA were 0.774 for SII, 0.705 for SIRI, and 0.819 for the combination of SII and SIRI.

Our findings demonstrate that both the SII and SIRI are independent risk factors for OSA and may serve as potential biomarkers for identifying individuals with OSA.