Relationship between non-alcoholic fatty liver disease and pulmonary function

Background: It has been observed that non-alcoholic fatty liver disease (NAFLD) is associated with an increased risk of cardiovascular disease and insulin resistance. Pulmonary function is also known to be related with cardiovascular disease and metabolic syndrome. Aims: The objective of this study was to investigate the association between NAFLD and pulmonary function. Methods: We performed a cross-sectional study to examine the association of NAFLD based on abdominal sonographic findings and pulmonary function in 2119 Korean men between the ages of 30 and 75. Forced vital capacity (FVC) and forced expiratory volume in 1s (FEV₁) were compared according to the presence of NAFLD. Univariate and multivariate logistic regression analyses were conducted to evaluate the relationship of NAFLD with FVC and FEV₁ as pulmonary function tests. Results: The subjects with NAFLD had lower FVC and FEV₁ than their non-steatotic counterparts, and FVC and FEV₁ gradually decreased according to the grade of hepatic steatosis. After adjusting for age, body mass index, smoking status, blood pressure, fasting plasma glucose, total cholesterol, hypertension, diabetes, triglyceride and high-density lipoprotein cholesterol, the FVC and FEV₁ were found to be inversely associated with the presence of NAFLD. Conclusion: NAFLD was independently associated with reduced pulmonary function, and the severity of NAFLD was inversely correlated with pulmonary function.