Xiandu Jin,1,2,* Yue Liu,2,* Wenjun Jia,2 Ruohang Xu,1 Xiuju Guan,3 Min Cui,1,2 Hanmo Zhang,1,2 Hao Wu,1,2 Liping Wei,2 Xin Qi2 

1School of Medicine, Nankai University, Tianjin, People’s Republic of China; 2Department of Cardiology, Tianjin Union Medical Center, The First Affiliated Hospital of Nankai University, Tianjin, People’s Republic of China; 3School of Graduate Studies, Tianjin University of Traditional Chinese Medicine, Tianjin, People’s Republic of China

*These authors contributed equally to this work

Correspondence: Xin Qi; Liping Wei, Department of Cardiology, Tianjin Union Medical Center, The First Affiliated Hospital of Nankai University, Tianjin, People’s Republic of China, Email qixinx2011@126.com; weilipingme@163.com

Background: The systemic immune-inflammatory index (SII) serves as a comprehensive indication of systemic inflammation. However, the relationship between SII and the severity of coronary artery lesions in participants with coronary artery disease (CAD) in different glucose metabolic states has not been fully elucidated.
Methods: A total of 2727 patients with CAD were enrolled between January 2018 and April 2022. SII was calculated as (platelet count × neutrophil count)/lymphocyte count. Participants were grouped by SII quartiles. Glucose metabolic status was classified as normal glucose regulation (NGR), pre-diabetes mellitus (Pre-DM) and diabetes mellitus (DM) according to World Health Organization guidelines. Logistic regression and restricted cubic spline models were applied to estimate the relationship between SII and severity of coronary artery lesions in different glucose metabolic states with further adjustments for confounders.
Results: Logistic regression analysis indicated a significant association between SII and coronary lesion severity (P < 0.05). Regardless of glucose metabolic status, Participants in the highest SII quartile (Q4) had a markedly higher risk of severe coronary lesions than those in the lowest quartile (Q1). After adjusting for confounders, a significant association between SII and coronary lesion severity was observed in the Pre-DM and DM individuals (P < 0.05), whereas not in the NGR individuals (P > 0.05). Subgroup analyses revealed that the association between SII and coronary lesion severity was consistent across age, gender, hypertension, antihypertensive drugs, hyperlipidemia, antilipidemic drugs, smokingand drinking (P > 0.05). Furthermore, restricted cubic spline modeling indicated a significant linear correlation between SII and coronary artery lesion severity.
Conclusion: The SII is a relatively stable indicator of inflammation and is positively correlated with coronary lesion severity. This study highlights the potential of SII as a novel inflammatory biomarker for assessing the coronary lesion severity among patients in different glucose metabolic states.

Keywords: systemic immune-inflammation index, SII, coronary heart disease, coronary artery disease severity, glucose metabolic status