Metabolic Dysfunction-associated Fatty Liver Disease is Associated with Greater Impairment of Lung Function than Nonalcoholic Fatty Liver Disease.

Background And Aims: We compared lung function parameters in nonalcoholic fatty liver disease (NAFLD) and metabolic dysfunction-associated fatty liver disease (MAFLD), and examined the association between lung function parameters and fibrosis severity in MAFLD.

Methods: In this cross-sectional study, we randomly recruited 2,543 middle-aged individuals from 25 communities across four cities in China during 2016 and 2020. All participants received a health check-up including measurement of anthropometric parameters, biochemical variables, liver ultrasonography, and spirometry. The severity of liver disease was assessed by the fibrosis (FIB)-4 score.

Results: The prevalence of MAFLD was 20.4% (=519) and that of NAFLD was 18.4% (=469). After adjusting for age, sex, adiposity measures, smoking status, and significant alcohol intake, subjects with MAFLD had a significantly lower predicted forced vital capacity (FVC, 88.27±17.60% vs. 90.82±16.85%, <0.05) and lower 1 s forced expiratory volume (FEV, 79.89±17.34 vs. 83.02±16.66%, <0.05) than those with NAFLD. MAFLD with an increased FIB-4 score was significantly associated with decreased lung function. For each 1-point increase in FIB-4, FVC was diminished by 0.507 (95% CI: -0.840, -0.173, =0.003), and FEV was diminished by 0.439 (95% CI: -0.739, -0.140, =0.004). The results remained unchanged when the statistical analyses was performed separately for men and women.

Conclusions: MAFLD was significantly associated with a greater impairment of lung function parameters than NAFLD.