Demographic and clinical characteristics of the study population
The total of 1786 participants aged 40-79 years were included, with 649 men and 1137 women. Participant characteristics are summarized by sex in Table 1. Men and women differed significantly in age, lifestyle factors such as smoking and drinking habits, WC, blood pressure, FPG, HDL-c, LDL-c, TC, and UA. The median VAI was 1.96±1.52 in men and 2.48±1.65 in women. As expected, the mean values of FVC%predicted and FEV1%predicted were lower in men than in women. FVC%predicted and FEV1% predicted were 84.13±14.69% and 85.18±16.81% in men and 86.93±15.73% and 93.20±17.95% in women, respectively. Additionally, the average FEV1/FVC in men and women was 80.66±9.38% and 83.98±7.37%, respectively.
FVC%predicted and FEV1%predicted in different quartiles of VAI
From the lowest to the highest quartile of VAI, the mean values of FVC%predicted were 87.05±1.20, 85.94±1.23, 81.10±1.11 and 82.43±1.01 in men (P for trend <0.001) and 91.62±0.94, 88.26±0.89, 86.01±0.88 and 80.66±0.37 in women (P for trend <0.001) (Fig. 1, Table 2). Strikingly, a greater FVC%predicted decrease corresponding with VAI increase was observed in women than in men. The same trend of FEV1%predicted was observed in women; FEV1%predicted decreased from 96.71±1.05 to 94.91±1.00, 92.56±1.03 and 88.66±1.11 as VAI quartiles increased. However, there was no significant difference between FEV1%predicted according to VAI quartiles in men (P for trend =0.074).
Association of the VAI with impaired lung function
Tables 3 and 4 show the correlation coefficients of lung function with the VAI and other metabolic variables. Pearson’s correlation analyses revealed that VAI, WC, age, SBP, FBG, HDL, UA and eGFR were significantly correlated with FVC%predicted in men, and VAI, WC, age, SBP, DBP, FBG, HDL, TC and UA were significantly correlated with FVC%predicted in women. However, after performing multivariate stepwise linear regression analysis, we found that VAI (β=-.098, .001) was only negatively and significantly correlated with FVC %predicted in addition to WC and SBP in women. Similarly, FEV1%predicted was positively associated with VAI, WC, age, SBP, DBP, FBG, HDL and UA. Only VAI (β=-.097, .002), age (-.137, <.001), WC (-.217, <.001), and SBP (-.072, .025) in women were independent factors in the multivariable stepwise linear regression analysis. In addition, in the linear regression analysis, the decrease in FVC%predicted associated with a 1-SD increase in the VAI was 1.776% in men and 3.421% in women; the decrease in FEV1% predicted associated with a 1-SD increase in the VAI was 1.045% in men and 3.060% in women (data not shown).
The results of the logistic regression analysis for predicting lung function impairment are presented in Table 5. In the univariate logistic regression model, the ORs for FVC impairment and FEV1 impairment associated with a 1-SD increase in the VAI were 1.185 (95% CI= 1.013-1.387; P=0.034) and 1.086 (95% CI= 0.925-1.276; P=0.313) in men and 1.44 (95% CI= 1.274-1.268; P<0.001) and 1.312 (95% CI= 1.149-1.497; P<0.001) in women, respectively. After adjusting for all confounding factors, the adjusted ORs for FVC impairment and FEV1 impairment per 1-SD increase in VAI were slightly weakened: 1.19 (95% CI= 0.991-1.428; P=0.062) and 1.116 (95% CI= 0.929-1.342; P=0.24) in men and 1.293 (95% CI= 1.129-1.481; P<0.001) and 1.278 (95% CI= 1.102-1.481; P=0.001) in women, respectively.
Demographic and clinical characteristics of the study population
The total of 1786 participants aged 40–79 years were included, with 649 men and 1137 women. Participant characteristics are summarized by sex in Table 1. Men and women differed significantly in age, lifestyle factors such as smoking and drinking habits, WC, blood pressure, FPG, HDL-c, LDL-c, TC, and UA. The median VAI was 1.96 ± 1.52 in men and 2.48 ± 1.65 in women. As expected, the mean values of FVC%predicted and FEV1%predicted were lower in men than in women. FVC%predicted and FEV1% predicted were 84.13 ± 14.69% and 85.18 ± 16.81% in men and 86.93 ± 15.73% and 93.20 ± 17.95% in women, respectively. Additionally, the average FEV1/FVC in men and women was 80.66 ± 9.38% and 83.98 ± 7.37%, respectively.
Table 1
Demographic and clinical characteristics of the study population
|
Men (649)
|
Women (1137)
|
P value
|
Age
|
57.39 ± 7.64
|
55.17 ± 8.02
|
P < 0.001
|
Smoking
|
328 (50.5%)
|
20 (1.8%)
|
P < 0.001
|
Drinking
|
320 (49.3%)
|
66 (5.8%)
|
P < 0.001
|
BMI
|
24.77 ± 3.25
|
24.82 ± 3.70
|
P = 0.793
|
WC
|
87.97 ± 9.16
|
84.02 ± 10.62
|
P < 0.001
|
Heart rate
|
76.91 ± 12.03
|
81.44 ± 11.54
|
P < 0.001
|
SBP
|
137.96 ± 19.18
|
133.24 ± 18.73
|
P < 0.001
|
DBP
|
84.18 ± 10.27
|
81.14 ± 10.10
|
P < 0.001
|
FPG
|
6.58 ± 1.90
|
6.33 ± 1.62
|
P = 0.003
|
HbA1c
|
5.79 ± 1.03
|
5.79 ± 0.99
|
P = 0.958
|
Insulin
|
6.96 ± 9.64
|
7.60 ± 4.05
|
P = 0.052
|
TGs
|
1.41 (0.99–2.17)
|
1.41 (1.00-2.02)
|
P = 0.637
|
HDL-c
|
1.28 ± 0.33
|
1.36 ± 0.29
|
P < 0.001
|
LDL-c
|
2.67 ± 0.70
|
2.82 ± 0.73
|
P < 0.001
|
TC
|
4.84 ± 0.86
|
5.05 ± 0.90
|
P < 0.001
|
VAI
|
1.96 ± 1.52
|
2.48 ± 1.65
|
P < 0.001
|
Uric acid
|
0.296 ± 0.069
|
0.232 ± 0.062
|
P < 0.001
|
Creatine
|
77.11 ± 15.92
|
63.34 ± 8.45
|
P < 0.001
|
eGFR
|
117.80 ± 24.64
|
122.18 ± 21.35
|
P < 0.001
|
FVC liter
|
3.22 ± 0.65
|
2.39 ± 0.47
|
P < 0.001
|
FVC%pred
|
84.13 ± 14.69
|
86.93 ± 15.73
|
P < 0.001
|
FEV liter
|
2.60 ± 0.60
|
2.01 ± 0.40
|
P < 0.001
|
FEV1%pred
|
85.18 ± 16.81
|
93.20 ± 17.95
|
P < 0.001
|
FEV1/FVC
|
80.66 ± 9.38
|
83.98 ± 7.37
|
P < 0.001
|
FVC%predicted and FEV1%predicted in different quartiles of VAI
From the lowest to the highest quartile of VAI, the mean values of FVC%predicted were 87.05 ± 1.20, 85.94 ± 1.23, 81.10 ± 1.11 and 82.43 ± 1.01 in men (P for trend < 0.001) and 91.62 ± 0.94, 88.26 ± 0.89, 86.01 ± 0.88 and 80.66 ± 0.37 in women (P for trend < 0.001) (Fig. 1, Table 2). Strikingly, a greater FVC%predicted decrease corresponding with VAI increase was observed in women than in men. The same trend of FEV1%predicted was observed in women; FEV1%predicted decreased from 96.71 ± 1.05 to 94.91 ± 1.00, 92.56 ± 1.03 and 88.66 ± 1.11 as VAI quartiles increased. However, there was no significant difference between FEV1%predicted according to VAI quartiles in men (P for trend = 0.074).
Table 2
Lung function in different quartiles of VAI
Men
|
|
|
|
|
VAI
|
Q1 (163)
|
Q2 (162)
|
Q3 (163)
|
Q4 (161)
|
P value
|
FVC liter
|
3.18 ± 0.67
|
3.27 ± 0.73
|
3.18 ± 0.63
|
3.26 ± 0.58
|
P = 0.407
|
FVC%pred
|
87.05 ± 1.20
|
85.94 ± 1.23
|
81.10 ± 1.11
|
82.43 ± 1.01
|
P < 0.001
|
FEV1 liter
|
2.55 ± 0.64
|
2.62 ± 0.63
|
2.58 ± 0.60
|
2.66 ± 0.51
|
P = 0.33
|
FEV1%pred
|
87.12 ± 1.47
|
86.41 ± 1.29
|
82.67 ± 1.35
|
84.54 ± 1.13
|
P = 0.074
|
FEV/FVC (%)
|
79.79 ± 0.84
|
80.30 ± 0.75
|
80.92 ± 0.71
|
81.65 ± 0.63
|
P = 0.316
|
Women
|
|
|
|
|
|
VAI
|
Q1 (284)
|
Q2 (279)
|
Q3 (290)
|
Q4 (284)
|
P value
|
FVC liter
|
2.48 ± 0.47
|
2.42 ± 0.48
|
2.39 ± 0.43
|
2.28 ± 0.47
|
P < 0.001
|
FVC%pred
|
91.62 ± 0.94
|
88.26 ± 0.89
|
86.01 ± 0.88
|
80.66 ± 0.37
|
P < 0.001
|
FEV1 liter
|
2.09 ± 0.41
|
2.04 ± 0.41
|
1.99 ± 0.36
|
1.91 ± 0.42
|
P < 0.001
|
FEV1%pred
|
96.71 ± 1.05
|
94.91 ± 1.00
|
92.56 ± 1.03
|
88.66 ± 1.11
|
P < 0.001
|
FEV1/FVC (%)
|
84.17 ± 0.42
|
84.17 ± 0.40
|
83.95 ± 0.51
|
83.98 ± 0.22
|
P = 0.819
|
The values of FVC%pred and FEV1%pred are shown as the means ± standard error of means. |
Abbreviations: VAI, visceral adiposity index; eGFR, estimated glomerular filtration rate; FVC, forced vital capacity; FEV1, forced expiratory volume in 1 s. |
Association of the VAI with impaired lung function
Tables 3 and 4 show the correlation coefficients of lung function with the VAI and other metabolic variables. Pearson’s correlation analyses revealed that VAI, WC, age, SBP, FBG, HDL, UA and eGFR were significantly correlated with FVC%predicted in men, and VAI, WC, age, SBP, DBP, FBG, HDL, TC and UA were significantly correlated with FVC%predicted in women. However, after performing multivariate stepwise linear regression analysis, we found that VAI (β=-.098, .001) was only negatively and significantly correlated with FVC %predicted in addition to WC and SBP in women. Similarly, FEV1%predicted was positively associated with VAI, WC, age, SBP, DBP, FBG, HDL and UA. Only VAI (β=-.097, .002), age (-.137, < .001), WC (-.217, < .001), and SBP (-.072, .025) in women were independent factors in the multivariable stepwise linear regression analysis. In addition, in the linear regression analysis, the decrease in FVC%predicted associated with a 1-SD increase in the VAI was 1.776% in men and 3.421% in women; the decrease in FEV1% predicted associated with a 1-SD increase in the VAI was 1.045% in men and 3.060% in women (data not shown).
Table 3
Factors associated with FVC%predicted by Pearson’s correlation and multivariable stepwise linear regression analysis
|
Men
|
Women
|
|
Pearson’s analysis
|
Stepwise linear regression analysis
|
Pearson’s analysis
|
Stepwise linear regression analysis
|
|
coefficient
|
P value
|
β
|
SE
|
t
|
P value
|
coefficient
|
P value
|
β
|
SE
|
t
|
P value
|
VAI
|
-0.12
|
P = 0.001
|
-0.123
|
0.37
|
-3.22
|
P = 0.001
|
-0.219
|
P < 0.001
|
-0.19
|
0.279
|
-6.4
|
P < 0.001
|
WC
|
-0.368
|
P < 0.001
|
-0.37
|
0.06
|
-10.4
|
P < 0.001
|
-0.351
|
P < 0.001
|
-0.291
|
0.046
|
-9.3
|
P < 0.001
|
Age
|
-0.203
|
P < 0.001
|
-0.186
|
0.08
|
-4.77
|
P < 0.001
|
0.075
|
P = 0.006
|
|
|
|
|
|
Heart rate
|
-0.019
|
P = 0.311
|
|
|
|
|
|
0.027
|
P = 0.183
|
|
|
|
|
|
SBP
|
-0.173
|
P < 0.001
|
-0.134
|
0.03
|
-3.52
|
P < 0.001
|
-0.193
|
P < 0.001
|
-0.15
|
0.025
|
-5.3
|
P < 0.001
|
DBP
|
-0.047
|
P = 0.115
|
|
|
|
|
|
-0.131
|
P < 0.001
|
|
|
|
|
|
FPG
|
-0.075
|
P = 0.028
|
|
|
|
|
|
-0.105
|
P < 0.001
|
|
|
|
|
|
HDL-c
|
0.092
|
P = 0.01
|
|
|
|
|
|
0.081
|
P = 0.003
|
|
|
|
|
|
LDL-c
|
-0.046
|
P = 0.119
|
|
|
|
|
|
-0.037
|
P = 0.109
|
|
|
|
|
|
TC
|
-0.046
|
P = 0.121
|
|
|
|
|
|
-0.07
|
P = 0.009
|
|
|
|
|
|
Uric acid
|
-0.121
|
P = 0.001
|
|
|
|
|
|
-0.14
|
P < 0.001
|
|
|
|
|
|
Creatine
|
-0.048
|
P = 0.113
|
|
|
|
|
|
-0.042
|
P = 0.077
|
|
|
|
|
|
eGFR
|
0.15
|
P < 0.001
|
0.085
|
0.02
|
2.199
|
P = 0.028
|
0.009
|
P = 0.378
|
|
|
|
|
|
Abbreviations: VAI, visceral adiposity index; WC, waist circumference; SBP, systolic blood pressure; DBP, diastolic blood pressure; FPG, fasting plasma glucose; HDL-c, high‐density lipoprotein cholesterol; LDL‐c, low‐density lipoprotein cholesterol; TC, total cholesterol; eGFR, estimated glomerular filtration rate. |
Table 4
Factors associated with FEV1%predicted by Pearson’s correlation and multivariable stepwise linear regression analysis
|
Men
|
Women
|
|
Pearson’s analysis
|
Stepwise linear regression analysis
|
Pearson’s analysis
|
Stepwise linear regression analysis
|
|
coefficient
|
P value
|
β
|
SE
|
t
|
P value
|
coefficient
|
P value
|
β
|
SE
|
t
|
P value
|
VAI
|
-0.062
|
P = 0.058
|
|
|
|
|
-0.171
|
P < 0.001
|
-0.17
|
0.324
|
-5.6
|
P < 0.001
|
WC
|
-0.285
|
P < 0.001
|
-0.287
|
0.07
|
-7.79
|
P < 0.001
|
-0.247
|
P < 0.001
|
-0.217
|
0.055
|
-6.7
|
P < 0.001
|
Age
|
-0.206
|
P < 0.001
|
-0.203
|
0.08
|
-5.29
|
P < 0.001
|
0.052
|
P = 0.04
|
0.131
|
0.071
|
4.16
|
P < 0.001
|
Heart rate
|
-0.024
|
P = 0.268
|
|
|
|
|
0.026
|
P = 0.193
|
|
|
|
|
SBP
|
-0.081
|
P = 0.02
|
|
|
|
|
-0.118
|
P < 0.001
|
-0.14
|
0.031
|
-4.3
|
P < 0.001
|
DBP
|
-0.014
|
P = 0.365
|
|
|
|
|
-0.08
|
P = 0.004
|
|
|
|
|
FPG
|
-0.021
|
P = 0.294
|
|
|
|
|
-0.071
|
P = 0.009
|
|
|
|
|
HDL-c
|
0.053
|
P = 0.089
|
|
|
|
|
0.079
|
P = 0.004
|
|
|
|
|
LDL-c
|
-0.054
|
P = 0.086
|
|
|
|
|
0.038
|
P = 0.103
|
|
|
|
|
TC
|
-0.044
|
P = 0.132
|
|
|
|
|
0.008
|
P = 0.389
|
|
|
|
|
Uric acid
|
-0.105
|
P = 0.004
|
-0.099
|
9.34
|
-2.59
|
P = 0.01
|
-0.068
|
P = 0.011
|
0.062
|
0.046
|
2.11
|
P = 0.035
|
Creatine
|
-0.015
|
P = 0.353
|
|
|
|
|
-0.033
|
P = 0.13
|
|
|
|
|
eGFR
|
0.095
|
P = 0.008
|
|
|
|
|
-0.001
|
P = 0.488
|
|
|
|
|
Abbreviations: VAI, visceral adiposity index; WC, waist circumference; SBP, systolic blood pressure; DBP, diastolic blood pressure; FPG, fasting plasma glucose; HDL-c, high‐density lipoprotein cholesterol; LDL‐c, low‐density lipoprotein cholesterol; TC, total cholesterol; eGFR, estimated glomerular filtration rate. |
The results of the logistic regression analysis for predicting lung function impairment are presented in Table 5. In the univariate logistic regression model, the ORs for FVC impairment and FEV1 impairment associated with a 1-SD increase in the VAI were 1.185 (95% CI = 1.013–1.387; P = 0.034) and 1.086 (95% CI = 0.925–1.276; P = 0.313) in men and 1.44 (95% CI = 1.274–1.268; P < 0.001) and 1.312 (95% CI = 1.149–1.497; P < 0.001) in women, respectively. After adjusting for all confounding factors, the adjusted ORs for FVC impairment and FEV1 impairment per 1-SD increase in VAI were slightly weakened: 1.19 (95% CI = 0.991–1.428; P = 0.062) and 1.116 (95% CI = 0.929–1.342; P = 0.24) in men and 1.293 (95% CI = 1.129–1.481; P < 0.001) and 1.278 (95% CI = 1.102–1.481; P = 0.001) in women, respectively.
Table 5
The risk of lung function impairment according to each 1-SD VAI increase
FVC impairment
|
FEV1 impairment
|
|
men
|
women
|
men
|
women
|
|
OR
|
P value
|
OR
|
P value
|
OR
|
P value
|
OR
|
P value
|
Model 1
|
1.185 (1.013–1.387)
|
P = 0.034
|
1.44 (1.274–1.268)
|
P < 0.001
|
1.086 (0.925–1.276)
|
P = 0.313
|
1.312 (1.149–1.497)
|
P < 0.001
|
Model 2
|
1.273 (1.075–1.507)
|
P = 0.006
|
1.414 (1.248–1.602)
|
P < 0.001
|
1.159 (0.977–1.376)
|
P = 0.091
|
1.296 (1.133–1.483)
|
P < 0.001
|
Model 3
|
1.19 (0.991–1.428)
|
P = 0.062
|
1.293 (1.129–1.481)
|
P < 0.001
|
1.116 (0.929–1.342)
|
P = 0.24
|
1.278 (1.102–1.481)
|
P = 0.001
|
Model 1 is unadjusted; |
Model 2 is adjusted for age, education, smoking and drinking; |
Model 3 is adjusted for age, education, smoking, drinking, SBP, DBP, heart rate, FPG, HbA1c, TC, uric acid, and eGFR. |
Abbreviations: FVC, forced vital capacity; FEV1, forced expiratory volume in 1 s; SBP, systolic blood pressure; DBP, diastolic blood pressure; FPG, fasting plasma glucose; TC, total cholesterol; eGFR, estimated glomerular filtration rate. |