Nonalcoholic Fatty Liver Disease Is Associated With Decreased Lung Function

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

Disclosures

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

In This Article

Results

Baseline Characteristics

Of the 11 892 participants (5617 males and 6275 females, mean age 47.7 ± 8.8 years), 3815 (32.1%) had ultrasonography-diagnosed NAFLD. The baseline characteristics of the subjects with and without NAFLD are shown in Table 1 and Table S2. The following factors were found to be significantly associated with NAFLD: older age, male gender, smoking, greater height, higher FVC, lower % of predicted FVC, higher FEV1, lower % of predicted FEV1, higher blood pressure, higher BMI, higher waist circumference, hypertension, diabetes and metabolic syndrome (all P < .001), as well as elevated levels of AST, ALT, GGT, total cholesterol, triglycerides, LDL cholesterol, fasting glucose, HbA1c and decreased level of HDL cholesterol (P < .001).

In the PS-matched cohort, most variables were balanced between groups, but several variables (triglyceride and BMI in male; fasting glucose and diabetes in female) were unbalanaced (P < .05) as described above (Table S2).

Association Between NAFLD and Baseline Lung Function in Cross-sectional Analysis

Table 2 shows the association between NAFLD and lung function in the total population. In unadjusted model, both FEV1 and FVC were significantly decreased in the NAFLD group in both males and females. After adjustment for age, BMI, smoking, waist circumference, hypertension, diabetes, triglycerides, HDL and LDL cholesterol, NAFLD was still associated with decreased FEV1 (3.52 vs 3.44 L, P < .001, in males; 2.62 vs 2.45 L, P < .001, in females) and FVC (4.33 vs 4.24 L, P < .001, in males; 3.11 vs 2.97 L, P < .001, in females) in both sexes.

Lung Function Decline According to the Presence or Absence of NAFLD in Longitudinal Analysis

Table 3 shows lung function decline according to the presence of NAFLD. The mean follow-up duration was 6.6 ± 2.2 years. During the follow-up, the NAFLD group showed reduced FEV1 decline rates in both sexes (men, −25.8 vs −29.8 mL/y, P < .001; women, −23.8 vs −26.7 mL/y, P < .001) and increased FVC decline rates in women (−23.4 vs −17.5 mL/y, P < .001) in adjusted model 1. There was no significant difference in the decline of FVC in males. The results were similar when propensity score was adjusted. However, in the PS-matched cohort (n = 4558), there was no significant difference in either FEV1 or FVC decline rate according to the presence of NAFLD in either sex.

Lung Function Decline Rate According to Hepatic Fibrosis as Evaluated by Noninvasive Methods

Figure 2 and Table S3 shows the rate of lung function decline according to noninvasive fibrosis markers (NFS and FIB–4) adjusted by age, BMI and smoking in the total cohort. There was no significant difference in FEV1 decline rate in both male and female. However, FVC decline rate was significantly increased in those with intermediate to high probability for advanced fibrosis group compared to those with low probability for advanced fibrosis group evaluated by NFS (−21.9 vs −26.2 mL/y, P = .010, in males) and FIB–4 (−21.7 vs −27.4 mL/y, P = .001 in males, −22.4 vs −27.9 mL/y, P = .016 in females).

Figure 2.

FVC decline rates according to the hepatic fibrosis evaluated by NAFLD fibrosis score and FIB–4 adjusted for age, body mass index and smoking in males and females. FVC decline rate was increased in those with intermediate to high probability for advanced fibrosis compared to those with low probability for advanced fibrosis in both sex. NFS, NAFLD fibrosis score; FIB–4, Fibrosis–4; FEV1, forced expiratory volume in 1–second; FVC, forced vital capacity. *NFS: low probability of advanced fibrosis <−1.455, high and intermediate probability of advanced fibrosis ≥−1.455. *FIB–4: low probability of advanced fibrosis <1.30, high and intermediate probability of advanced fibrosis ≥1.30

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