Abstract
PURPOSE: Systemic Immune-Inflammation Index (SII), calculated by (neutrophils count × platelet count)/lymphocytes count, is a novel index of the local immune response and systemic inflammation response. The SII has been shown to play an important role in the prognosis of many diseases, including cardiovascular diseases, cancer and COPD. However, its role in the prognosis of bronchiectasis remains unclear and requires further investigation. This study aimed to investigate the association between SII and readmissions in patients with acute exacerbations of bronchiectasis. PATIENTS AND METHODS: We conducted a retrospective cohort study of all bronchiectasis patients admitted to the respiratory ward in Beijing Chaoyang Hospital from January 2020 to January 2022. Patients were classified into four groups according to the quartiles of log(2)(SII) at admission. The primary endpoint was readmission at 1-year follow up. Univariate and multivariate cox regression models were applied to investigate the relationship between SII and readmissions at 1-year follow up in patients with bronchiectasis. RESULTS: A total of 521 patients were included in our study. The median (IQR) SII at admission were 506.10 (564.84). Patients with higher SII tended to be older, male, past and current smokers, have lower BMI, and more dyspnea symptoms. They also had higher inflammatory markers and received a greater spectrum of antibiotics and more intravenous glucocorticoids. Higher SII at admission were independently associated with readmission in patients with acute exacerbations for bronchiectasis following confounder adjustment (OR =1.007; 95% CI, 1.003-1.011; p <0.001). CONCLUSION: Patients with elevated SII levels were typically older males, often smokers, with lower BMI and increased dyspnea. They received more antibiotics and intravenous glucocorticoids. Higher SII at admission are associated with readmission in patients with acute exacerbations of bronchiectasis. SII has potential clinical value as a predictive biomarker for clinical outcomes in bronchiectasis, offering a valuable tool for management strategies.