A total of 21,772 subjects with complete data sets were included in the final analysis. Most participants were from central China (56.9%), and some were from the southwest, east and north. The mean age was 49.9 ± 12.3 years and 64.2% of the subjects were male (Table 1). The prevalence of metabolic syndrome was 29.5% and 10.5% in men and women respectively.
Table 1. General characteristics of the participants
|
Total (n=21772)
|
Men (n=13968)
|
Women (n=7804)
|
P value
|
Age, years
|
49.9 ± 12.3
|
50.1 ± 12.5
|
49.6 ± 11.8
|
0.0033
|
Region of China, n (%)
|
|
|
|
<0.0001
|
North
|
80 (0.4)
|
47 (0.3)
|
33 (0.4)
|
|
East
|
3052 (14.0)
|
1917 (13.7)
|
1135 (14.5)
|
|
Center
|
12390 (56.9)
|
7686 (55.0)
|
4704 (60.3)
|
|
Southwest
|
6250 (28.7)
|
4318 (30.9)
|
1932 (24.8)
|
|
BMI, kg/m2
|
24.6 ± 3.2
|
25.2 ± 3.0
|
23.4 ± 3.1
|
<0.0001
|
Visceral adipose tissue area, cm2
|
175 ± 82
|
207 ± 76
|
119 ± 56
|
<0.0001
|
Waist circumference, cm
|
86 ± 10
|
90 ± 8
|
79 ± 9
|
<0.0001
|
Systolic blood pressure, mmHg
|
126 ± 19
|
128 ± 18
|
123 ± 20
|
<0.0001
|
Diastolic blood pressure, mmHg
|
77 ± 12
|
79 ± 12
|
73 ± 11
|
<0.0001
|
Fasting plasma glucose, mmol/L
|
5.26 ± 1.39
|
5.38 ± 1.51
|
5.04 ± 1.11
|
<0.0001
|
Triglycerides, mmol/L
|
1.44 (1.02, 2.11)
|
1.59 (1.12, 2.31)
|
1.21 (0.89, 1.73)
|
<0.0001
|
HDL cholesterol, mmol/L
|
1.36 ± 0.36
|
1.27 ± 0.32
|
1.52 ± 0.36
|
<0.0001
|
Rate of metabolic abnormalities, n (%)
|
|
|
|
|
High blood pressure
|
9094 (41.8)
|
6536 (46.8)
|
2558 (32.8)
|
<0.0001
|
High fasting plasma glucose
|
2598 (11.9)
|
2063 (14.8)
|
535 (6.86)
|
<0.0001
|
High triglycerides
|
8363 (38.4)
|
6320 (45.2)
|
2043 (26.2)
|
<0.0001
|
Low HDL cholesterol
|
3475 (16.0)
|
3021 (21.6)
|
454 (5.82)
|
<0.0001
|
High waist circumference
|
9050 (41.6)
|
7115 (50.9)
|
1935 (24.8)
|
<0.0001
|
Metabolic syndrome
|
4943 (22.7)
|
4123 (29.5)
|
820 (10.5)
|
<0.0001
|
Age-adjusted metabolic syndrome
|
19.6
|
25.9
|
8.3
|
|
Values are shown as mean ± standard deviation, median (quartiles), or n (%). BMI, body mass index; HDL, high-density lipoprotein.
Age-adjusted prevalence of metabolic abnormalities among levels of VAT area
With increasing VAT area, the prevalence of hypertension, dyslipidemia, high waist circumference and metabolic syndrome increased significantly in both males and females (P<0.05, Figure 1). Compared with patients with low VAT (<60cm2), men with high VAT (>360cm2) were more likely to have metabolic syndrome (0.7% vs. 62.2%, p<0.0001). Similarly, women with high VAT (>240cm2) had a higher prevalence of metabolic syndrome than those with low VAT (<40cm2, 0% vs. 38.9%, p<0.0001).
Optimal VAT thresholds based on cardiometabolic risk factors
The optimal VAT measurements for identifying metabolic syndrome that were obtained from ROC curves (Figure 2A) were 213 cm2 in men, and 136 cm2 in women, respectively. These thresholds were found to be the optimum thresholds for discriminating metabolic syndrome. The corresponding sensitivity and specificity were 77.0% and 65.1% in men and 84.3% and 71.2% in women respectively (Table 2). The positive and negative predictive values are also presented in Table 2. The calibration plot performed well both in the male and female cohorts (Figure 2B). Similar optimal VAT thresholds for subjects from different regions of China are shown in Supplement Table 1.
Table 2. Thresholds of visceral adipose tissue area for the identification of metabolic syndrome in men and women
|
Men
|
Women
|
Threshold points, cm2
|
213
|
136
|
Sensitivity, %
|
77.0
|
84.3
|
Specificity, %
|
65.1
|
71.2
|
Positive predictive value, %
|
48.0
|
25.5
|
Negative predictive value, %
|
87.1
|
97.5
|
Diagnostic accuracy, %
|
68.6
|
72.5
|
Status of cardiometabolic risk factors stratified by VAT threshold values
Table 3 compares cardiometabolic risk factors for men and women with VAT area above and below their sex specific threshold points (213 cm2 for men and 136 cm2 for women). The subjects with VAT area over the threshold values had significantly higher BMI, waist circumference, systolic blood pressure, diastolic blood pressure, fasting plasma glucose, triglycerides and lower HDL cholesterol for both men and women (P<0.0001).
Table 3. Levels of risk factors for metabolic syndrome in male and female participants stratified by thresholds of visceral adipose tissue area
|
Men (n=13968)
|
|
Women (n=7804)
|
|
<213 cm2 (n=7361)
|
≥213 cm2 (n=6607)
|
P value
|
|
<136 cm2 (n=5099)
|
≥136 cm2 (n=2705)
|
P value
|
Age, years
|
47.8 ± 12.9
|
52.6 ± 11.7
|
<0.0001
|
|
46.1 ± 11.1
|
56.1 ± 10.3
|
<0.0001
|
BMI, kg/m2
|
23.7 ± 2.4
|
27.0 ± 2.6
|
<0.0001
|
|
22.1 ± 2.4
|
25.8 ± 2.8
|
<0.0001
|
Waist circumference, cm
|
85 ± 7
|
95 ± 7
|
<0.0001
|
|
75 ± 7
|
86 ± 7
|
<0.0001
|
Systolic blood pressure, mmHg
|
124 ± 16
|
133 ± 18
|
<0.0001
|
|
117 ± 17
|
133 ± 20
|
<0.0001
|
Diastolic blood pressure, mmHg
|
76 ± 11
|
83 ± 12
|
<0.0001
|
|
70 ± 11
|
77 ± 11
|
<0.0001
|
Fasting plasma glucose, mmol/L
|
5.16 ± 1.34
|
5.63 ± 1.64
|
<0.0001
|
|
4.84 ± 0.75
|
5.44 ± 1.51
|
<0.0001
|
Triglycerides, mmol/L
|
1.37 (0.99, 1.95)
|
1.87 (1.34, 2.70)
|
<0.0001
|
|
1.07 (0.81, 1.45)
|
1.60 (1.16, 2.20)
|
<0.0001
|
HDL cholesterol, mmol/L
|
1.33 ± 0.33
|
1.20 ± 0.29
|
<0.0001
|
|
1.58 ± 0.36
|
1.40 ± 0.33
|
<0.0001
|
Values are shown as mean ± standard deviation or median (quartiles). BMI, body mass index; HDL, high-density lipoprotein.
Prevalence ratio of cardiometabolic risk factors with the VAT threshold values
Age adjusted logistic regression analysis showed that the prevalence of hypertension, hyperglycemia, dyslipidemia, high waist circumference and metabolic syndrome significantly increased among subjects with VAT area ≥ 213 cm2 for men or 136 cm2 for women. Table 4 shows the odds ratios and results for population attributable risk.
Table 4. Population attributable risks for metabolic abnormalities by visceral adipose tissue area threshold points of 213 cm2 for men and 136 cm2 for women
|
Men
|
|
Women
|
|
OR (95% CI) *
|
PAR (%)
|
|
OR (95% CI) *
|
PAR (%)
|
High BP
|
2.33 (2.17, 2.50)
|
38.6
|
|
2.23 (2.00, 2.50)
|
29.9
|
High FPG
|
2.22 (2.01, 2.46)
|
36.6
|
|
3.36 (2.73, 4.14)
|
45.0
|
High TG
|
3.08 (2.87, 3.31)
|
49.6
|
|
3.61 (3.22, 4.05)
|
47.5
|
Low HDL-C
|
2.09 (1.92, 2.28)
|
34.0
|
|
2.85 (2.30, 3.53)
|
39.0
|
High WC
|
14.5 (13.4, 15.8)
|
86.5
|
|
12.6 (11.0, 14.4)
|
80.0
|
Metabolic syndrome
|
6.15 (5.65, 6.69)
|
70.9
|
|
9.25 (7.58, 11.4)
|
74.1
|
*Age-adjusted OR and 95% CI values.
BP, blood pressure; CI, confidence interval; FPG, fasting plasma glucose; HDL-C, high-density lipoprotein cholesterol; OR, odd ratio; PAR, population attributable risk; TG, triglyceride; VAT, visceral adipose tissue; WC, waist circumference.