Associations between high-density lipoprotein cholesterol and interstitial lung abnormalities in the Korean national lung cancer screening programme

Background High-density lipoprotein (HDL) cholesterol exerts anti-inflammatory, antioxidative and endothelial-protective effects, yet its role in interstitial lung abnormalities (ILA) remains unclear. Methods We analysed baseline screening from heavy smokers who participated in the Korean national lung cancer screening programme (2019–2021). HDL cholesterol was measured at two pre-screening time points (remote and immediate) and categorised as normal or low. Participants were also classified into four HDL cholesterol trajectories: normal-to-normal, low-to-normal, normal-to-low and low-to-low. We used logistic regression to estimate odds ratios for ILA, adjusting for demographic characteristics, body mass index, lifestyle factors, comorbidities, income status, lipid profiles and statin use. Results Among 159 729 participants (mean age 61.7 years, 98.2% men), ILA were detected in 2.9%, with higher prevalence in those with low HDL cholesterol at immediate pre-screening compared with normal HDL cholesterol (3.5% versus 2.7%). There was a higher proportion of obesity (6.1% versus 3.5%) and more frequent statin use (40.0% versus 34.4%) among participants with low HDL cholesterol than among those with normal HDL cholesterol. ILA prevalence increased from the normal-to-normal HDL cholesterol group (2.6%) across the low-to-normal (3.1%), normal-to-low (3.5%) and low-to-low (3.6%) groups. Low HDL at immediate pre-screening was associated with a 28% higher risk of ILA (95% CI 1.19–1.38; p