A Comparative Analysis of Systemic Immune-inflammation Index in Patients with Stable and Acute Exacerbation of Chronic Obstructive Pulmonary Disease

Background: Chronic obstructive pulmonary disease (COPD) is a leading cause of global morbidity and mortality, particularly during acute exacerbations of COPD (AECOPD), which contribute to increased healthcare burden. Systemic inflammation is central to COPD pathogenesis. The systemic immune-inflammation index (SII)–calculated as (neutrophils × platelets)/lymphocytes–is a novel inflammatory marker gaining recognition in various diseases. This study assesses SII as a biomarker to differentiate AECOPD from stable COPD and to predict clinical outcomes. Methods: In this prospective, single-center case–control study, 96 spirometry-confirmed COPD patients were enrolled over 12 months–48 patients with AECOPD and 48 with stable disease. Data on demographics, smoking history, comorbidities, and outcomes were collected. SII was calculated from complete blood counts. Logistic regression was used to analyze associations between SII and outcomes, adjusting for confounders. Results: Mean SII was significantly higher in AECOPD patients (2250 ± 460) than in stable COPD (1450 ± 330; P < 0.001). Among AECOPD patients, smokers (n = 41) showed higher SII (2450 ± 500) compared to stable smokers (~1550). Within the AECOPD group, SII ≥2500 was associated with poorer outcomes: prolonged hospitalization (80%), need for mechanical ventilation (75%), and in-hospital mortality (60%)–all statistically significant ( P < 0.01). SII remained an independent predictor after adjusting for confounders. Conclusion: SII is a cost-effective, accessible biomarker that effectively differentiates AECOPD from stable COPD and predicts adverse clinical outcomes. Incorporating SII into routine evaluation may aid in early risk stratification and timely intervention. Further research is warranted to validate threshold values.