A58-20 Epidemiological Characteristics and Risk Factors of Interstitial Lung Abnormalities: A Large-Scale Retrospective Cohort Study in China

Rationale

Although interstitial lung abnormalities (ILA) are increasingly recognized as potential precursors to clinically significant interstitial lung disease, large-scale population-based data on their incidence and risk factors remain limited. This study aimed to investigate the prevalence, incidence, and risk factors of ILA in a large Chinese cohort.

Methods

We conducted a retrospective cohort study of 324,734 participants with 393,454 CT scans. Incidence densities were calculated per 1000 person-years. Risk factors were evaluated using stratified analyses, univariate and multivariate logistic, and random forest modeling. To address missing data and examine the robustness of the findings, we performed complete-case analyses and multiple imputation, along with sensitivity analyses using both logistic and Cox regression models.

Results

The incidence density of ILA was 6.61 per 1000 personyears (95% CI 6.02-7.25). Smoking (HR = 1.74), advanced age (≥60 years; 3.6fold increased risk), and male gender (HR = 1.73) were all significantly associated with higher ILA risk (all p < 0.0001). In multivariate analysis, male gender (OR = 1.63), advanced age (OR = 1.08), smoking (OR = 1.12), cough (OR = 1.22), and dyspnea (OR = 1.23) were risk factors for ILA, whereas good stove ventilation (OR = 0.89) and childhood respiratory infections (OR = 0.60) appeared protective. For pulmonary nodules, risk factors included male gender (OR = 1.08), age (OR = 1.03), frequent kitchen-fume exposure (OR = 1.04), childhood respiratory infections (OR = 1.11), smoking (OR = 1.07-1.14), dyspnea (OR = 1.05), wheezing (OR = 1.21), and ILA (OR = 1.45) (all p < 0.05; AUC for ILA=0.746, for pulmonary nodule=0.933). Joint-exposure analysis using random forest indicated that solid-fuel use contributed most to ILA prediction accuracy (MeanDecreaseAccuracy [MDA]=2.35), followed by frequent kitchen-fume exposure (MDA=1.85), separation of kitchen and living area (MDA=1.71), secondhand smoke exposure (MDA=1.61), and smoking history (MDA=1.53). Smoking history (MeanDecreaseGini [MDG]=0.103), good stove ventilation [MDG]=1.02), and secondhand smoke exposure (MDG=1.01) also showed relatively high variable importance.

Conclusions

This large-scale study reveals distinct epidemiological patterns of ILA in the Chinese population. Male gender, advanced age, and smoking are key risk factors for ILA, while good stove ventilation appears protective. ILA itself constitutes a risk factor for pulmonary nodules. Solid-fuel use emerged as the strongest exposure-related predictor of ILA, underscoring the importance of household air quality in respiratory health.

This abstract is funded by: None