Nonalcoholic Fatty Liver Disease Is Associated With Decreased Lung Function

Chang-Hoon Lee; Seung Ho Choi; Goh Eun Chung; Boram Park; Min-Sun Kwak


Liver International. 2018;38(11):2091-2100. 

In This Article



Details of study population

Among them, we excluded 4,427 subjects with at least 1 potential cause of chronic liver disease including excessive alcohol consumption (>30 g/day for men and >20 g/day for women), chronic viral hepatitis (determined by the presence of hepatitis B surface antigen or anti-hepatitis C antibodies), other types of hepatitis (such as primary biliary cholangitis, Wilson's disease, and hemochromatosis), liver cirrhosis, hepatocellular carcinoma, and history of hepatic resection. Furthermore, we excluded 2,617 subjects with underlying lung disease including lung cancer, asthma, chronic obstructive pulmonary disease (COPD), and history of pulmonary tuberculosis or lung resection. Additionally, 708 subjects who did not undergo spirometry or hepatic ultrasonography were excluded. We also excluded 477 subjects under 30 years old. Ultimately, 11,892 subjects were included in the cohort (Figure 1).

Clinical and laboratory assessments

Body weight and height were measured using a digital scale, and body mass index (BMI) was calculated by dividing weight (kg) by the square of height (m2). A well-trained individual used a measuring tape to assess waist circumference at the midpoint between the lower costal margin and the anterior superior iliac crest. Systolic blood pressure and diastolic blood pressure were measured twice, and mean values were reported. Patients were regarded as having hypertension if they had systolic blood pressure ≥140 mmHg or diastolic blood pressure ≥90 mmHg in more than two measurements or were taking anti-hypertensive medication. Patients were classified as having diabetes if they were taking anti-diabetic medications or had a fasting serum glucose level of at least 126 mg/dL.

The laboratory tests included assessments of serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), total cholesterol, triglycerides, high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, total protein, albumin, bilirubin, alkaline phosphatase, gamma glutamyl transferase (GGT), fasting glucose, uric acid, HbA1c, blood urea nitrogen (BUN), creatinine, hepatitis B surface antigen and antibodies against hepatitis C virus, as well as white blood cell, hemoglobin, and platelet counts. Blood samples were collected before 10:00 AM after a 12-h overnight fast. All laboratory tests were conducted using standard laboratory methods.