Hyun Woo Lee1, Dong Hyeon Lee2, Jung-Kyu Lee1, Seonhwa Lee3, Bo Kyung Koo4, Sae Kyung Joo2, Eun Young Heo1, Yong Jin Jung2, Won Kim2,5, Deog Kyeom Kim1,5. 1. Division of Respiratory and Critical Care, Department of Internal Medicine, Seoul Metropolitan Government Seoul National University Boramae Medical Center, Seoul, South Korea. 2. Division of Gastroenterology and Hepatology, Department of Internal Medicine, Seoul Metropolitan Government Seoul National University Boramae Medical Center, Seoul, South Korea. 3. Department of Bio-convergence Engineering, Korea University, Seoul, South Korea. 4. Division of Endocrinology, Department of Internal Medicine, Seoul Metropolitan Government Seoul National University Boramae Medical Center, Seoul, South Korea. 5. Department of Internal Medicine, Seoul National University College of Medicine, Seoul, South Korea.
Abstract
BACKGROUND & AIMS: The association between nonalcoholic fatty liver disease (NAFLD) and pulmonary function remains elusive because of the heterogeneous spectrum and inaccurate diagnostic methods of NAFLD, and insufficient pulmonary function data. We conducted this study to identify the association between histological severity of NAFLD and pulmonary function. METHODS: This study included patients ≥18 years old with baseline pulmonary function data between August 2014 and July 2019 within a biopsy-evaluated prospective NAFLD cohort. Cross-sectionally, pre-/post-bronchodilator spirometric data with diffusing capacity (DLCO ) were compared according to histological severity of NAFLD in the various demographic and metabolic subgroups. Multivariable-adjusted analysis revealed specific histological features associated with reduced pulmonary function. RESULTS: In a total of 420 patients with biopsy-proven NAFLD, pre-/post-bronchodilator forced vital capacities (FVCs; a percentage of the predictive value) were inversely correlated with histological severity of NAFLD. Conversely, pre-bronchodilator forced expiratory volume in 1 second (FEV1 )/FVC was positively correlated with NAFLD severity. Post-bronchodilator FVC (%) decreased and DLCO /alveolar volume (VA ) increased linearly with worsening histological severity of NAFLD in multivariable analysis. In particular, fibrosis stage remained a significant independent predictor of decreased post-bronchodilator FVC (%) (β-coefficient, 4.41; 95% confidence interval [-8.39, -0.43]; P = .031) even after adjusted for clinical variables, exclusively in age <65 years, female, never-smoker and nonchronic obstructive pulmonary disease subgroups. CONCLUSIONS: Pulmonary function deteriorates with worsening histological severity of NAFLD, especially at the fibrosis stage. The common pathogenesis of reduced pulmonary function and NAFLD fibrosis progression should be further explored.
BACKGROUND & AIMS: The association between nonalcoholic fatty liver disease (NAFLD) and pulmonary function remains elusive because of the heterogeneous spectrum and inaccurate diagnostic methods of NAFLD, and insufficient pulmonary function data. We conducted this study to identify the association between histological severity of NAFLD and pulmonary function. METHODS: This study included patients ≥18 years old with baseline pulmonary function data between August 2014 and July 2019 within a biopsy-evaluated prospective NAFLD cohort. Cross-sectionally, pre-/post-bronchodilator spirometric data with diffusing capacity (DLCO ) were compared according to histological severity of NAFLD in the various demographic and metabolic subgroups. Multivariable-adjusted analysis revealed specific histological features associated with reduced pulmonary function. RESULTS: In a total of 420 patients with biopsy-proven NAFLD, pre-/post-bronchodilator forced vital capacities (FVCs; a percentage of the predictive value) were inversely correlated with histological severity of NAFLD. Conversely, pre-bronchodilator forced expiratory volume in 1 second (FEV1 )/FVC was positively correlated with NAFLD severity. Post-bronchodilator FVC (%) decreased and DLCO /alveolar volume (VA ) increased linearly with worsening histological severity of NAFLD in multivariable analysis. In particular, fibrosis stage remained a significant independent predictor of decreased post-bronchodilator FVC (%) (β-coefficient, 4.41; 95% confidence interval [-8.39, -0.43]; P = .031) even after adjusted for clinical variables, exclusively in age <65 years, female, never-smoker and nonchronic obstructive pulmonary disease subgroups. CONCLUSIONS: Pulmonary function deteriorates with worsening histological severity of NAFLD, especially at the fibrosis stage. The common pathogenesis of reduced pulmonary function and NAFLD fibrosis progression should be further explored.