Relationship between obstructive lung disease and non-alcoholic fatty liver disease in the Korean population: Korea National Health and Nutrition Examination Survey, 2007–2010

Figures & data

Table 1 Subject characteristics according to the presence of NAFLD

Variables	Non-NAFLD group	NAFLD group	P-value
Unweighted number, n (%)	8,168 (69.6)	3,570 (30.4)
Estimated population, n (%)	16,415,120 (69.8)	7,131,971 (30.2)
Age (years), %	45.93 (45.22–46.64)	51.81 (50.84–52.78)	<0.001
20–39	36.9 (34.8–39.1)	23.9 (21.4–26.6)	<0.001
40–59	42.1 (40.2–44.0)	40.7 (38.3–43.1)	<0.001
60+	21.0 (19.6–22.5)	35.4 (33.1–37.8)	<0.001
Sex (male), %	35.8 (34.2–37.4)	48.3 (45.8–50.8)	<0.001
BMI (kg/m^2)	23.27 (23.17–23.38)	26.03 (25.85–26.21)	<0.001
Smoking, %			<0.001
Non-smoker	64.8 (63.2–66.4)	56.2 (53.7–58.6)
Ex-smoker	3.3 (2.8–3.8)	5.9 (4.9–7.1)
Current smoker	31.9 (30.3–33.6)	37.9 (35.5–40.4)
Smoking amount (PYRs)	18.13 (16.93–19.32)	19.28 (17.83–20.73)	<0.001
Metabolic syndrome, %	12.6 (11.4–13.8)	74.6 (72.1–77.0)	<0.001
Diabetes mellitus, %	1.8 (1.5–2.2)	24.2 (22.2–26.2)	<0.001
Hypertension, %	15.5 (14.3–16.8)	50.0 (47.3–52.7)	<0.001
Pulmonary function test
FVC (L)	3.56 (3.52–3.59)	3.51 (3.45–3.56)	<0.001
FEV1 (L)	2.86 (2.83–2.89)	2.78 (2.74–2.82)	<0.001
FEV1 (%)	92.62 (92.15–93.08)	91.07 (90.44–91.70)	<0.001
FEV1/FVC ratio	0.80 (0.80–0.81)	0.79 (0.79–0.80)	<0.001
OLD, %	8.5 (7.7–9.4)	10.0 (8.8–11.4)	0.060
AST (IU/L)	19.75 (19.50–20.01)	27.22 (26.37–28.07)	<0.001
ALT (IU/L)	17.40 (17.09–17.71)	33.89 (32.53–35.25)	<0.001
LFSa	−1.83 (−1.86 to −1.80)	0.63 (0.55–0.71)	<0.001

Notes: Values are presented as percentage and mean (95% CI) unless otherwise specified. OLD is defined as FEV₁/FVC ratio <0.7.

a LFS = 22.89 + 1.18 × metabolic syndrome + 0.45 × diabetes + 0.15 × fasting insulin + 0.04 × AST (IU/l) + 0.94 × AST/ALT ratio.

Abbreviations: NAFLD, non-alcoholic fatty liver disease; BMI, body mass index; PYRs, pack years; FVC, forced vital capacity; FEV₁, forced expiratory volume; OLD, obstructive lung disease; AST, aspartate aminotransferase; ALT, alanine aminotransferase; LFS, liver fat score; CI, confidence interval.

Table 2 Logistic regression analyses of factors related to NAFLD

Variables	OR	95% CI	P-value
Age, years
20–39	1.000
40–59	1.917	1.682–2.185	<0.001
60+	3.011	2.509–3.613	<0.001
Sex, male	1.852	1.538–2.231	<0.001
Smoking status
Never smoker	1.000
Ex-smoker	0.980	0.808–1.189	0.694
Current smoker	0.890	0.681–1.163	0.694
OLD	1.556	1.288–1.879	<0.001

Note: Values are presented as ORs with 95% CIs.

Abbreviations: NAFLD, non-alcoholic fatty liver disease; OR, odds ratio; CI, confidence interval; OLD, obstructive lung disease.

Table 3 Logistic regression analyses of factors related to OLD

Variables	OR	95% CI	P-value
Age, years
20–39	1.000
40–59	6.196	5.102–7.525	<0.001
60+	27.402	17.135–43.820	<0.001
Sex, male	2.159	1.628–2.864	<0.001
Smoking status
Never smoker	1.000
Ex-smoker	2.227	1.569–3.300	<0.001
Current smoker	2.016	1.517–2.680	<0.001
NAFLD	1.334	1.108–1.607	0.002

Note: Values are presented as ORs with 95% CIs.

Abbreviations: OLD, obstructive lung disease; OR, odds ratio; CI, confidence interval; NAFLD, non-alcoholic fatty liver disease.

Figure S1 Flow diagram of the subjects who were included in this study.

Abbreviations: PFT, pulmonary function test; AST, aspartate aminotransferase; ALT, alanine aminotransferase; HBV, hepatitis B virus; HCV, hepatitis C virus; OLD, obstructive lung disease; NAFLD, non-alcoholic fatty liver disease.

Table S1 Subject characteristics according to the presence of OLD

Variables	Non-OLD group	OLD group	P-value
Unweighted number, n (%)	10,459 (89.1)	1,279 (10.9)
Estimated population, n (%)	21,433,227 (91.1)	2,113,864 (8.9)
Age (years), %	46.08 (45.47–46.70)	64.25 (63.03–65.47)	<0.001
20–39	35.7 (33.9–37.6)	5.1 (3.3–7.9)	<0.001
40–59	43.2 (41.6–44.9)	25.5 (22.2–29.1)	<0.001
60+	21.0 (19.8–22.3)	69.4 (65.5–73.1)	<0.001
Sex (male), %	37.2 (35.8–38.6)	63.3 (59.1–67.3)	<0.001
BMI (kg/m^2)	24.18 (24.09–24.29)	23.36 (23.10–23.63)	<0.001
Smoking, %
Non-smoker	64.7 (63.3–66.0)	37.2 (33.2–41.4)	<0.001
Ex-smoker	3.3 (2.9–3.8)	11.8 (9.4–14.8)	<0.001
Current smoker	32.0 (30.7–33.5)	51.0 (46.4–55.6)	<0.001
Smoking history (PYRs)	16.83 (15.78–17.87)	27.80 (25.23–30.38)	<0.001
Metabolic syndrome, %	29.9 (28.4–31.3)	46.7 (42.6–50.8)	<0.001
Diabetes mellitus, %	7.9 (7.2–8.7)	15.3 (12.7–18.3)	<0.001
Hypertension, %	26.2 (24.9–27.5)	47.8 (43.9–51.8)	<0.001
Pulmonary function test
FVC (L)	3.56 (3.53–3.59)	3.34 (63.03–65.47)	<0.001
FEV1 (L)	2.91 (2.88–2.93)	2.12 (2.06–2.17)	<0.001
FEV1 (%)	93.73 (93.36–94.11)	76.06 (74.88–77.23)	<0.001
FEV1/FVC ratio	0.82 (0.81–0.82)	0.63 (0.63–0.64)	<0.001
AST (IU/L)	21.94 (21.57–22.31)	22.80 (22.21–23.38)	<0.001
ALT (IU/L)	22.57 (22.01–23.14)	20.60 (19.77–21.43)	<0.001
LFSa	−1.10 (−1.15 to −1.05)	−0.98 (−1.13 to −0.82)	<0.001
NAFLD, %	30.0 (28.6–31.3)	33.7 (30–37.6)	0.060

Notes: Values are presented as percentage and mean (95% CI) unless otherwise specified.

a LFS = 22.89 + 1.18 × metabolic syndrome + 0.45 × diabetes + 0.15 × fasting insulin + 0.04 × AST (IU/l) + 0.94 × AST/ALT ratio. OLD is defined as FEV₁/FVC ratio <0.7.

Abbreviations: OLD, obstructive lung disease; BMI, Body Mass Index; PYRs, pack years; FVC, forced vital capacity; FEV₁, forced expiratory volume; AST, aspartate aminotransferase; ALT, alanine aminotransferase; LFS, liver fat score; NAFLD, non-alcoholic fatty liver disease; CI, confidence interval.