A clinical study of pulmonary function changes in patients with nonalcoholic fatty liver disease

Objective To investigate the pulmonary function changes in patients with nonalcoholic fatty liver disease (NAFLD) and their clinical significance.Methods A total of 275 NAFLD patients who underwent physical examination in Physical Examination Center of Daping Hospital, Army Medical University, from September 2016 to May 2017 were enrolled as NAFLD group, and 276 non-NAFLD patients were enrolled as control group.Pulmonary function data were analyzed for both groups, including forced vital capacity (FVC) , forced expiratory volume in the first second (FEV1) , and FEV1/FVC ratio, and pulmonary function parameters were compared between NAFLD patients with elevated alanine aminotransferase (ALT) and those with normal ALT.The two-independent-samples t test was used for comparison of continuous data with homogeneity of variance between groups, and the non-parametric Wilcoxon rank-sum test was used for comparison of continuous data with heterogeneity of variance between groups.The chi-square test was used for comparison of categorical data between groups.Results Compared with the control group, the NAFLD group had significantly lower FVC (3.60 ± 0.87 L vs 3.87 ± 0.80 L, t =-3.78, P < 0.01) and FEV1 (2.97 ± 0.79 L vs 3.17 ± 0.82 L, t =-2.87, P < 0.01) .The NAFLD group had a slightly lower FEV1/FVC ratio than the control group (82.06% + 13.88% vs 82.88% ± 13.0%, P > 0.05) .Compared with those with normal ALT, the NAFLD patients with elevated ALT had lower FVC (3.53 ± 0.82 L vs 3.69 ± 0.92 L, P > 0.05) , FEV1 (2.72 ± 0.80 L vs 3.06 ± 0.79 L, P > 0.05) , and FEV1/FVC ratio (81.21% ± 13.00% vs 82.69% ± 12.92%, P > 0.05) .Conclusion NAFLD patients may have pulmonary function damage, which may be associated with metabolic disorder and liver inflammation.