Baseline characteristics
565 subjects were included in this survey, including 221 males (39.1%). The average age of the total population was 40.33 ± 11.86 years, of which the average age of men was 42.10 ± 12.93 years, and women 39.20 ± 10.99 years. The average age of men was, statistically, significantly higher than that of women., and the difference was statistically significant (P = 0.011). In a comparison of baseline characteristics between the two sexes, the levels of WC, SBP, DBP, TG, TBIL, IBIL, ALT, and AST were higher in men than women, and HDL-C levels were higher in women than men. The differences were statistically significant (P < 0.05). As shown in Table 1.
Table 1 Baseline characteristics based on different genders
|
Total
|
Men
|
Women
|
P
|
Number (%)
|
565
|
221(39.1)
|
344(60.9)
|
|
Age (years)
|
40.33±11.86
|
42.10±12.93
|
39.20±10.99
|
0.011
|
Smoking, N (%)
|
187(33.1)
|
117(52.9)
|
70(20.3)
|
<0.001
|
Drinking, N (%)
|
55(9.7)
|
52(23.5)
|
3(0.9)
|
<0.001
|
WC (cm)
|
81.58±9.97
|
83.64±9.77
|
80.26±9.88
|
<0.001
|
SBP (mmHg)
|
127.84±21.72
|
132.10±21.64
|
125.11±21.36
|
<0.001
|
DBP (mmHg)
|
81.92±13.79
|
84.06±13.52
|
80.54±13.81
|
<0.001
|
FPG (mmol/L)
|
4.37±0.97
|
4.48±1.12
|
4.29±0.86
|
0.214
|
TG (mmol/L)
|
1.05±0.84
|
1.05±0.52
|
1.05±0.99
|
0.018
|
TC (mmol/L)
|
4.13±0.94
|
4.17±0.86
|
4.11±0.99
|
0.212
|
HDL-C (mmol/L)
|
1.42±0.37
|
1.36±0.36
|
1.46±0.38
|
<0.001
|
LDL-C (mmol/L)
|
2.08±0.67
|
2.13±0.64
|
2.04±0.69
|
0.054
|
BMI (kg/m2)
|
23.26±3.44
|
23.43±3.32
|
23.15±3.51
|
0.359
|
TBIL (μmol/L)
|
10.84±4.70
|
11.84±4.71
|
10.19±4.59
|
<0.001
|
IBIL (μmol/L)
|
8.08±3.82
|
8.76±3.88
|
7.65±3.73
|
<0.001
|
DBIL (μmol/L)
|
2.58±1.48
|
2.72±1.56
|
2.48±1.42
|
0.054
|
ALT (IU/L)
|
15.34±10.36
|
16.43±8.28
|
14.64±11.45
|
<0.001
|
AST (IU/L)
|
27.37±12.48
|
28.70±11.84
|
26.52±12.82
|
0.002
|
WC, waist circumference; SBP, systolic blood pressure; DBP, diastolic blood pressure; FPG, fasting plasma glucose; TG, Triglycerides; TC, total cholesterol, HDL-C, high-density lipoprotein cholesterol, LDL-C, low-density lipoprotein cholesterol; BMI, body mass index; TBIL, total bilirubin ; IBIL,indirect bilirubin; DBIL, direct bilirubin, ALT, alanine aminotransferase; AST, aspartate aminotransferase
|
The incidence of metabolic syndrome
The subjects were followed up for 3233.04 person-years, with an average follow-up time of 5.72 ± 1.49 years per subject. During this period, a total of 204 subjects developed MS, with a cumulative incidence of 36.11% and the incidence density was 63.10/1000 person-years. Among them, 70 men had MS, the cumulative incidence was 31.67%, and the incidence density was 55.71 / 1000 person-years. The cumulative incidence increased with age (χ2 trend = 43.166, P < 0.001) and 134 women had MS, the cumulative incidence was 38.95% and the incidence density was 67.80 / 1000 person-years. The cumulative incidence increased with age (χ2 trend = 76.391, P < 0.001). There was no statistically significant difference in cumulative incidence and incidence density between men and women. As shown in Table 2.
Table 2 Comparison of the incidence of metabolic syndrome in different age groups
Group
|
Number
|
Number of MS
|
Cumulative incidence (%)
|
Incidence density
(10-3person-years)
|
χ2trend
|
P
|
total
|
565
|
204
|
36.11
|
63.10
|
|
|
men
|
221
|
70
|
31.67
|
55.71
|
|
|
<35
|
69
|
14
|
20.29
|
36.75
|
43.166
|
<0.001
|
35-45
|
70
|
23
|
32.86
|
54.96
|
>45
|
82
|
33
|
40.24
|
72.19
|
women
|
344
|
134
|
38.95
|
67.80
|
|
|
<35
|
128
|
38
|
29.69
|
51.49
|
76.391
|
<0.001
|
35-45
|
121
|
51
|
42.15
|
72.24
|
>45
|
95
|
45
|
47.37
|
84.52
|
Analysis of influencing factors for metabolic syndrome
We divided the indicators into four groups from low to high, according to the quartile, and explored the relationship between the different quartile levels and the risk of MS. After adjusting for age, sex, smoking, drinking, waist circumference, blood pressure, fasting plasma glucose, triglyceride, and high-density lipoprotein cholesterol, we found that TBIL and IBIL levels were negatively correlated with MS. Compared to the lowest quartile level (Q1), the HR (95% CI) of TBIL Q2-Q4 levels were 0.408 (0.266-0.626), 0.374 (0.244-0.572), and 0.328 (0.216-0.500), and that of IBIL Q2-Q4 were 0.572 (0.374-0.875), 0.432 (0.283-0.659), and 0.434 (0.289-0.653). With the increase of TBIL and IBIL levels, its negative correlation with MS also increased. However, there was no correlation between DBIL, ALT, or AST and MS. As shown in Table 3.
Table 3 Analysis of influencing factors for incident metabolic syndrome
Parameter
|
HR
|
95%CI
|
P
|
TBIL
|
|
|
|
Q1
|
ref
|
ref
|
ref
|
Q2
|
0.408
|
0.266-0.626
|
<0.001
|
Q3
|
0.374
|
0.244-0.572
|
<0.001
|
Q4
|
0.328
|
0.216-0.500
|
<0.001
|
IBIL
|
|
|
|
Q1
|
ref
|
ref
|
ref
|
Q2
|
0.572
|
0.374-0.875
|
0.010
|
Q3
|
0.432
|
0.283-0.659
|
<0.001
|
Q4
|
0.434
|
0.289-0.653
|
<0.001
|
DBIL
|
|
|
|
Q1
|
ref
|
ref
|
ref
|
Q2
|
1.191
|
0.792-1.793
|
0.401
|
Q3
|
1.185
|
0.786-1.785
|
0.418
|
Q4
|
0.969
|
0.633-1.481
|
0.883
|
ALT
|
|
|
|
Q1
|
ref
|
ref
|
ref
|
Q2
|
1.057
|
0.690-1.620
|
0.799
|
Q3
|
1.165
|
0.746-1.820
|
0.502
|
Q4
|
0.978
|
0.607-1.576
|
0.929
|
AST
|
|
|
|
Q1
|
ref
|
ref
|
ref
|
Q2
|
0.711
|
0.477-1.060
|
0.094
|
Q3
|
0.747
|
0.488-1.142
|
0.178
|
Q4
|
1.003
|
0.643-1.565
|
0.988
|
Analysis adjusted for age, sex, smoking, drinking, waist circumference, blood pressure, fasting plasma glucose, triglycerides, and high-density lipoprotein cholesterol
|
Correlation analysis of serum bilirubin, transaminase and MS components
From multivariate Cox regression model analysis, TBIL and IBIL levels were found to be negatively correlated with increased blood pressure, increased waist circumference, and increased triglycerides. The risk of elevated blood pressure, increased waist circumference, and elevated triglycerides at the highest quartile level of TBIL (Q4) was 0.479, 0.484, and 0.498 respectively, at the lowest quartile (Q1). AST levels were positively correlated with elevated fasting glucose and triglycerides. The highest quartile levels of fasting glucose and triglycerides were 2.33 times and 2.20 times that of the lowest quartile. No correlation was found between DBIL, ALT and the occurrence of MS components. As shown in Table 4.
Correlation analysis of serum bilirubin, transaminase and MS at baseline with different components
Multivariate Cox regression analysis showed that, in the populations with no MS component or one MS component, at baseline, each index was not related to the risk of MS. In a population with two MS components at baseline, TBIL and IBIL levels are negatively correlated with the risk of MS. Compared to the lowest quartile level (Q1), the risk HRs (95% CI) of TBIL Q2-Q4 group were 0.410 (0.232, 0.725), 0.413 (0.232, 0.737), and 0.351 (0.198, 0.624), and those of the IBIL Q2-Q4 group were 0.380 (0.212, 0.682), 0.335 (0.190, 0.593), and 0.302 (0.165, 0.553). With an increase in TBIL and IBIL levels, the risk of MS is gradually reduced. However, DBIL, ALT, and AST are not related to the risk of MS. As shown in Table 5.
Table 4 Correlation analysis of serum bilirubin, transaminase and MS components
|
Elevated blood pressure a (n=351)
|
|
Increased waist circumference b (n=366)
|
|
Raised fasting glucose c
(n=676)
|
|
Raised triglycerides d
(n=602)
|
|
Reduced HDL-C e
(n=515)
|
|
HR (95%CI)
|
P
|
|
HR (95%CI)
|
P
|
|
HR(95%CI)
|
P
|
|
HR(95%CI)
|
P
|
|
HR(95%CI)
|
P
|
TBIL
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Q1
|
ref
|
ref
|
|
ref
|
ref
|
|
ref
|
ref
|
|
ref
|
ref
|
|
ref
|
ref
|
Q2
|
0.427(0.265,0.689)
|
<0.001
|
|
0.587(0.387,0.891)
|
0.012
|
|
1.080(0.557,2.091)
|
0.820
|
|
0.536(0.329,0.873)
|
0.012
|
|
0.706(0.465,1.072)
|
0.102
|
Q3
|
0.371(0.213,0.645)
|
<0.001
|
|
0.537(0.333,0.866)
|
0.011
|
|
0.987(0.488,1.998)
|
0.972
|
|
0.688(0.423,1.119)
|
0.132
|
|
0.760(0.497,1.164)
|
0.207
|
Q4
|
0.479(0.299,0.765)
|
0.002
|
|
0.484(0.306,0.765)
|
0.002
|
|
0.623(0.300,1.294)
|
0.205
|
|
0.498(0.300,0.826)
|
0.007
|
|
0.702 (0.461,1.068)
|
0.099
|
IBIL
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Q1
|
ref
|
ref
|
|
ref
|
ref
|
|
ref
|
ref
|
|
ref
|
ref
|
|
ref
|
ref
|
Q2
|
0.596(0.361,0.981)
|
0.042
|
|
0.528(0.348,0.800)
|
0.003
|
|
1.161(0.592,2.277)
|
0.664
|
|
0.573(0.351,0.937)
|
0.026
|
|
0.818(0.527,1.269)
|
0.370
|
Q3
|
0.439(0.266,0.726)
|
0.001
|
|
0.460(0.295,0.716)
|
0.001
|
|
1.335(0.667,2.673)
|
0.414
|
|
0.669(0.414,1.078)
|
0.099
|
|
0.954(0.615,1.478)
|
0.832
|
Q4
|
0.641(0.405,1.015)
|
0.058
|
|
0.447(0.281,0.709)
|
0.001
|
|
0.865(0.422,1.773)
|
0.692
|
|
0.606(0.368,0.997)
|
0.049
|
|
0.776(0.501,1.203)
|
0.257
|
DBIL
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Q1
|
ref
|
ref
|
|
ref
|
ref
|
|
ref
|
ref
|
|
ref
|
ref
|
|
ref
|
ref
|
Q2
|
0.865(0.516,1.451)
|
0.583
|
|
1.134(0.737,1.746)
|
0.568
|
|
0.808(0.459,1.422)
|
0.459
|
|
1.214(0.780,1.889)
|
0.389
|
|
1.066(0.752,1.513)
|
0.718
|
Q3
|
1.505(0.933,2.428)
|
0.093
|
|
1.329(0.860,2.054)
|
0.200
|
|
0.805(0.431,1.504)
|
0.496
|
|
1.165(0.724,1.876)
|
0.529
|
|
0.856(0.567,1.294)
|
0.461
|
Q4
|
0.860(0.529,1.398)
|
0.543
|
|
0.828(0.528,1.297)
|
0.410
|
|
0.570(0.318,1.023)
|
0.060
|
|
0.631(0.382,1.041)
|
0.071
|
|
0.792(0.545,1.153)
|
0.224
|
ALT
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Q1
|
ref
|
ref
|
|
ref
|
ref
|
|
ref
|
ref
|
|
ref
|
ref
|
|
ref
|
ref
|
Q2
|
1.054(0.630,1.762)
|
0.842
|
|
1.238(0.795,1.927)
|
0.345
|
|
1.531(0.818,2.865)
|
0.183
|
|
1.230(0.757,1.999)
|
0.403
|
|
1.117(0.741,1.682)
|
0.597
|
Q3
|
1.000(0.627,1.597)
|
0.998
|
|
1.141(0.756,1.723)
|
0.530
|
|
1.069(0.588,1.942)
|
0.827
|
|
1.159(0.728,1.846)
|
0.534
|
|
0.862(0.594,1.250)
|
0.433
|
Q4
|
0.854(0.500,1.458)
|
0.563
|
|
1.381(0.857,2.225)
|
0.185
|
|
0.995(0.509,1.944)
|
0.988
|
|
0.708(0.406,1.234)
|
0.223
|
|
0.758(0.504,1.141)
|
0.185
|
AST
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Q1
|
ref
|
ref
|
|
ref
|
ref
|
|
ref
|
ref
|
|
ref
|
ref
|
|
ref
|
ref
|
Q2
|
0.652(0.400,1.063)
|
0.087
|
|
1.087(0.706,1.674)
|
0.704
|
|
1.431(0.686,2.986)
|
0.339
|
|
1.323(0.645,2.716)
|
0.445
|
|
1.113(0.721,1.171)
|
0.629
|
Q3
|
0.644(0.381,1.068)
|
0.100
|
|
1.028(0.655,1.614)
|
0.904
|
|
1.816(0.891,3.703)
|
0.101
|
|
1.736(0.856,3.522)
|
0.126
|
|
1.073(0.706,1.630)
|
0.742
|
Q4
|
1.231(0.752,2.017)
|
0.409
|
|
1.505(0.941,2.406)
|
0.088
|
|
2.335(1.128,4.836)
|
0.022
|
|
2.200(1.075,4.502)
|
0.031
|
|
1.075(0.689,1.677)
|
0.751
|
a. The model with adjustment for age, sex, waist circumference, fasting blood glucose, triglycerides and high-density lipoprotein cholesterol;
b. The model with adjustment for age, sex, blood pressure, fasting blood glucose, triglycerides and high-density lipoprotein cholesterol;
c. The model with adjustment for age, sex, blood pressure, waist circumference, triglycerides and high-density lipoprotein cholesterol;
d. The model with adjustment for age, sex, blood pressure, waist circumference, fasting blood glucose and high-density lipoprotein cholesterol;
e. The model with adjustment for age, sex, blood pressure, waist circumference, fasting blood glucose and triglycerides.
|
Table 5 Analysis of serum bilirubin, transaminase and MS at baseline with different components
|
MS component number = 0
(n=104)
|
|
MS component number = 1
(n=237)
|
|
MS component number = 2
(n=224)
|
|
HR(95%CI)
|
P
|
|
HR(95%CI)
|
P
|
|
HR(95%CI)
|
P
|
TBIL
|
|
|
|
|
|
|
|
|
Q1
|
ref
|
ref
|
|
ref
|
ref
|
|
ref
|
ref
|
Q2
|
5.476(0.561,53.467)
|
0.144
|
|
0.524(0.226,1.213)
|
0.131
|
|
0.410(0.232,0.725)
|
0.002
|
Q3
|
3.556(0.406,31.146)
|
0.252
|
|
0.671(0.297,1.515)
|
0.337
|
|
0.413(0.232,0.737)
|
0.003
|
Q4
|
2.695(0.281,25.886)
|
0.390
|
|
0.698(0.307,1.587)
|
0.391
|
|
0.351(0.198,0.624)
|
<0.001
|
IBIL
|
|
|
|
|
|
|
|
|
Q1
|
ref
|
ref
|
|
ref
|
ref
|
|
ref
|
ref
|
Q2
|
2.776(0.283,27.212)
|
0.381
|
|
0.551(0.265,1.145)
|
0.110
|
|
0.380(0.212,0.682)
|
0.001
|
Q3
|
5.992(0.679,52.894)
|
0.107
|
|
0.388(0.174,0.865)
|
0.021
|
|
0.335(0.190,0.593)
|
<0.001
|
Q4
|
2.809(0.302,26.120)
|
0.364
|
|
0.734(0.371,1.455)
|
0.376
|
|
0.302(0.165,0.553)
|
<0.001
|
DBIL
|
|
|
|
|
|
|
|
|
Q1
|
ref
|
ref
|
|
ref
|
ref
|
|
ref
|
ref
|
Q2
|
0.799(0.182,3.509)
|
0.766
|
|
1.539(0.729,3.250)
|
0.259
|
|
1.269(0.738,2.183)
|
0.388
|
Q3
|
1.494(0.375,5.943)
|
0.569
|
|
1.879(0.829,4.258)
|
0.131
|
|
1.280(0.743,2.204)
|
0.374
|
Q4
|
0.222(0.041,1.215)
|
0.083
|
|
1.460(0.715,2.982)
|
0.299
|
|
0.954(0.521,1.746)
|
0.878
|
ALT
|
|
|
|
|
|
|
|
|
Q1
|
ref
|
ref
|
|
ref
|
ref
|
|
ref
|
ref
|
Q2
|
0.699(0.168,2.908)
|
0.623
|
|
0.923(0.454,1.880)
|
0.826
|
|
1.225(0.656,2.289)
|
0.524
|
Q3
|
1.419(0.386,5.215)
|
0.599
|
|
0.926(0.439,1.954)
|
0.840
|
|
1.184(0.614,2.280)
|
0.614
|
Q4
|
0.406(0.085,1.942)
|
0.259
|
|
0.602(0.247,1.464)
|
0.263
|
|
1.287(0.661,2.509)
|
0.458
|
AST
|
|
|
|
|
|
|
|
|
Q1
|
ref
|
ref
|
|
ref
|
ref
|
|
ref
|
ref
|
Q2
|
1.049(0.297,3.703)
|
0.941
|
|
0.743(0.356,1.553)
|
0.430
|
|
0.602(0.348,1.041)
|
0.070
|
Q3
|
1.941(0.463,8.134)
|
0.364
|
|
0.575(0.272,1.218)
|
0.148
|
|
0.694(0.385,1.251)
|
0.224
|
Q4
|
0.948(0.183,4.919)
|
0.950
|
|
0.786(0.349,1.773)
|
0.562
|
|
0.976(0.534,1.782)
|
0.937
|
The model with adjustment for smoking, drinking, age, sex, waist circumference, blood pressure, fasting blood glucose, triglycerides, and high-density lipoprotein cholesterol.
|