Relationship between systemic immune response index (SIRI) and COPD: a cross-sectional study based on NHANES 2007–2012

Although the link between inflammation and chronic obstructive pulmonary disease (COPD) is increasingly recognized, the correlation between systemic immune response index (SIRI), a novel marker of inflammation, and COPD is unknown. This cross-sectional study used data from patients with complete lung function in NHANES 2007-2012 to explore the relationship between SIRI and COPD. We performed a series of statistical analyses on a total of 5056 participants, including multiple linear regression, smoothed curve fitting, ROC curve analysis, and subgroup analysis. In the fully corrected model, the logistic multiple regression showed that SIRI was associated with a high risk of COPD (OR1.350, 95% CI:1.220,1.493). The ROC curve showed that SIRI (AUC = 0.596) was significantly more efficient than other inflammatory factors in predicting COPD. Smoothed curve fit effect and threshold effect analyses showed a linear correlation between SIRI COPD prevalence, and subgroup analyses showed that the effect of SIRI on COPD was more pronounced in still smokers (OR 1.58, 95% CI: 1.34, 1.86) versus men (OR 1.62, 95% CI: 1.44, 1.83). The results of the interaction test provide evidence supporting SIRI as an independent risk factor for COPD.