Xiang Wen,1,* Xiaohui Wu,1,* Zhishan Deng,1,* Fan Wu,1,2 Huajing Yang,1 Shan Xiao,1 Cuiqiong Dai,1 Changli Yang,3 Shuqing Yu,4 Ruiting Sun,1 Pixin Ran,1,2 Yumin Zhou1 

1State Key Laboratory of Respiratory Disease & National Clinical Research Center for Respiratory Disease & National Center for Respiratory Medicine & Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, People’s Republic of China; 2Guangzhou National Laboratory, Guangzhou, Guangdong, People’s Republic of China; 3Wengyuan County People’s Hospital, Shaoguan, People’s Republic of China; 4Lianping County People’s Hospital, Heyuan, People’s Republic of China

*These authors contributed equally to this work

Correspondence: Yumin Zhou; Pixin Ran, Email zhouyumin410@126.com; pxran@gzhmu.edu.cn

Background: The previous findings on the correlation between spirometry and high-density lipoprotein (HDL) cholesterol are intriguing yet conflicting. The aim of this research is to evaluate the relationship between HDL levels and spirometry as well as imaging parameters in patients with chronic obstructive pulmonary disease (COPD) in China.
Methods: This study encompasses a total of 907 COPD patients. Participants with complete data from questionnaire interviews, lipid profile examinations, spirometry testing, and computed tomography (CT) scans were included in the analysis. A generalized additive model was employed to identify the non-linear relationship between HDL levels and both spirometry and imaging parameters. In the presence of non-linear correlations, segmented linear regression model was applied to ascertain threshold effects.
Results: After adjusting for various factors, we found a non-linear correlation between HDL levels and spirometry/imaging parameters, with an inflection point at 4.2 (66 mg/dL). When Ln (HDL) was below 4.2, each unit increase correlated significantly with reduced post-bronchodilator FEV1 (0.32L, 95% CI: 0.09– 0.55), decreased predicted FEV1% (11.0%, 95% CI: 2.7– 19.3), and lowered FEV1/FVC (8.0%, 95% CI: 4.0– 12.0), along with notable increases in Ln (LAA− 950) by 1.20 (95% CI: 0.60– 1.79) and Ln (LAA− 856) by 0.77 (95% CI: 0.37– 1.17). However, no significant associations were observed when Ln (HDL) was greater than or equal to 4.2.
Conclusion: A non-linear correlation existed between HDL levels with lung function and CT imaging in COPD patients. Prior to reaching 66 mg/dL, an elevation in HDL was significantly associated with impaired lung function, more severe gas trapping and emphysema.

Keywords: COPD, high-density lipoprotein, lung function, computed tomography imaging