Significant association of urinary copper levels with bronchiectasis in non-smokers living in the vicinity of petrochemical complex: a population-based study

Abstract

Abstract Copper in particulate matter was associated with increased incidence of respiratory disease. However, the association between urinary copper levels and interstitial lung changes remains unclear. We conducted this population-based study in southern Taiwan during 2016 and 2018. We excluded individuals with history of lung carcinoma, pneumonia, and smoking. Low-dose computed tomography (LDCT) were performed for all participants. Lung interstitial changes included the presence of ground-glass opacity (GGO) or bronchiectasis in LDCT images. We categorized urinary copper levels into quartiles (Q) (Q1: ≤1.03; Q2: >1.04 and ≤ 1.42; Q3: >1.43 and ≤ 1.89, and Q4: >1.90 µg/dL). The risk of interstitial lung changes was calculated by multiple logistic regression analysis. The highest quartile (Q4) (5.3%) of urinary copper levels had significantly higher ratio of bronchiectasis than other quartiles (Q1: 2.1%, vs. Q2: 3.2%, vs. Q3: 2.1%, p = 0.049). We found that the highest quartiles of urinary copper levels (Q4) (OR: 3.38, 95% CI: 1.17–9.75; p = 0.024) was significantly associated with an increased risk of bronchiectasis compared with the lowest quartile (Q1) of urinary copper levels after adjustment for urinary creatinine, age, gender, ALT, diabetes mellitus, hypertension, waist circumference, triglycerides, and HDL-C. The dose-response trend was significant (Ptrend= 0.045). There is no significant association between GGO and quartiles of urinary copper levels. We observed that urinary copper levels were significantly associated with bronchiectasis. A significant dose-response effect was observed. The relationship between copper exposure and interstitial lung disease needs more studies to elucidate in the future.