Yu Han,1,* Yutao Wu,1,* Yihao Li,2,* Huilin Xia,2 Zhihao Cai,1 Li Qiao,1 Xiaomeng Zhang,1 Zibei Chang,1 Peng Huang,2 Jianqing Wu,1 Bo Chen1 

1Department of Geriatrics, Jiangsu Province Hospital, The First Affiliated Hospital with Nanjing Medical University, Nanjing, People’s Republic of China; 2Department of Epidemiology, School of Public Health, Nanjing Medical University, Nanjing, People’s Republic of China

*These authors contributed equally to this work

Correspondence: Bo Chen, Department of Geriatrics, Jiangsu Province Hospital, The First Affiliated Hospital with Nanjing Medical University, Nanjing, People’s Republic of China, Email chenbo361du@163.com Jianqing Wu, Department of Geriatrics, Jiangsu Province Hospital, The First Affiliated Hospital with Nanjing Medical University, Nanjing, People’s Republic of China, Email Jwuny@njmu.edu.cn

Background: Chronic obstructive pulmonary disease (COPD) is the third leading cause of death worldwide. Previous studies have explored the relationship between different dietary patterns, systemic inflammation index (SII)and the risk of COPD. However, the joint effects and interactions between SII and HEI-2015 in COPD have not been fully investigated. This study aimed to explore the relationships between COPD and SII and HEI-2015.
Methods: Data from the National Health and Nutrition Examination Surveys (NHANES) were utilized.Univariate and multivariate logistic regression analyzed the associations between SII and HEI– 2015 with COPD. Restricted cubic spline (RCS) model analyzed the relationship between SII and HEI-2015 and COPD.Use the area enclosed under the ROC curve (AUC) to represent its predicted value. Interaction indices and subgroup analyses were performed. The Kaplan-Meier curve was used to evaluate the impact on mortality of COPD patients.
Results: This study included 10,898 participants.After adjusting,logistic regression analysis showed that higher SII (OR=1.03, 95% CI: 1.01– 1.05) were associated with an increased risk of COPD, while higher HEI-2015 (OR=0.97, 95% CI: 0.96– 0.99) reduced the risk.The RCS model observed a non-linear relationship between SII and HEI-2015 and COPD risk. Additionally, ROC showed a more significant advantage in predicting COPD prevalence (AUC=0.68). Interaction analysis indicated that SII and HEI-2015 might be independent influencing factors for COPD risk. Kaplan–Meier survival curves showed a lower all-cause mortality rate among in the group with high SII and low HEI-2015 (p < 0.0001).
Conclusion: The results of this study indicate that a higher SII level and a lower HEI-2015 are associated with COPD risk. COPD patients with higher SII levels combined with lower HEI - 2015 levels have a higher all-cause death risk.

Keywords: chronic obstructive pulmonary disease, systemic inflammation index, dietary quality, NHANES