The association between blood manganese and liver stiffness in participants with chronic obstructive pulmonary disease: a cross-sectional study from NHANES 2017–2018

Background To explore the relationship between blood manganese and liver stiffness in the United States among participants with chronic obstructive pulmonary disease (COPD). Methods All data were obtained from the 2017–2018 National Health and Nutrition Examination Survey database (NHANES). A total of 4690 participants were included in the study. All participants included complete information on COPD, liver stiffness, and blood manganese. Liver stiffness (kPa) was measured from “Examination Date” and blood manganese (ug/L) was obtained from “Laboratory Data”. A multiple linear regression model was used to assess the correlation between blood manganese and liver stiffness. Results Among the 4690 participants, blood manganese was lower in the COPD group but liver stiffness was higher ( p < 0.05). There was a positive correlation between blood manganese and liver stiffness ( β = 0.08, 95% CI 0.03, 0.12). This positive association was more pronounced in COPD participants ( β = 0.25, 95% CI 0.08, 0.42) and there was a non-linear relationship, which was more significant when blood manganese exceeded 14.43 ug/L ( β = 1.76, 95% CI 1.10, 2.41). Conclusions The association between blood manganese and liver stiffness was positive, which was more apparent in COPD patients.