Abstract:Objective To investigate the correlation between systemic immune-inflammation index（SII）and respiratory failure in patients with acute exacerbation of chronic obstructive pulmonary disease（AECOPD），and the predictive efficiency of SII for respiratory failure in AECOPD patients. Methods Clinical data of 102 AECOPD patients admitted to Anhui No.2 Provincial People's Hospital from November 2023 to February 2025 were retrospectively collected. The patients were divided into the observation group（n=48）and the control group（n=54）according to the presence or absence of respiratory failure. Levels of C-reactive protein（CRP），D-dimer（D-D），albumin（ALB），fibrinogen（FIB），neutrophil count（NEU），platelet count（PLT），lymphocyte count（LYM），red blood cell distribution width（RDW），mean platelet volume（MPV），plateletcrit（PCT），platelet distribution width（PDW），SII，neutrophil-to-lymphocyte ratio（NLR），and platelet-to-lymphocyte ratio（PLR）were compared between the two groups. Logistic regression was used to analyze influencing factors of respiratory failure secondary to AECOPD，and receiver operating characteristic（ROC）curve was applied to evaluate the predictive value of SII for respiratory failure. Results Compared with the control group，CRP，NEU，NLR，PLR，SII，and FIB were significantly higher（P＜0.05），while ALB and LYM were significantly lower in the observation group（P＜0.05）. Multivariate logistic regression showed that high SII（OR =1.003，95%CI：1.001-1.005），high CRP（OR =1.016，95%CI：1.000-1.030），and low ALB（OR =0.861，95%CI：0.753-0.983）were independent risk factors for respiratory failure in AECOPD patients（P＜0.05）. ROC curve analysis showed that the area under the curve（AUC）of SII in predicting respiratory failure in AECOPD patients was 0.809. Conclusion SII can be used as an effective indicator for predicting respiratory failure in AECOPD patients.