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Table 1 Clinical characteristics of the study participants according to total bilirubin and gamma-glutamyltransferase classifications

From: Potential impact of the joint association of total bilirubin and gamma-glutamyltransferase with metabolic syndrome

(A) Men Total bilirubin (μmol/L) p-value
< 15.4 ≥ 15.4
Gamma-glutamyltransferase (μkat/L) Gamma-glutamyltransferase (μkat/L)
< 0.44 ≥ 0.44 < 0.44 ≥ 0.44
n 1303 1331 1007 945  
Age (years) 44.3 ± 10.0 45.7 ± 9.4 43.0 ± 9.6 45.3 ± 9.2 < 0.0001
Follow-up interval (years) 2.8 ± 1.2 2.8 ± 1.2 2.8 ± 1.2 2.8 ± 1.2 0.5846
Body mass index (kg/m2) 22.5 ± 2.5 23.9 ± 3.0 22.1 ± 2.4 23.7 ± 3.0 < 0.0001
Current smoking 352 (27.0) 385 (28.9) 150 (14.9) 146 (15.5) < 0.0001
Exercise habit 315 (24.2) 293 (22.0) 242 (24.0) 218 (23.1) 0.5476
Waist circumference (cm) 81.0 ± 7.1 84.8 ± 7.6 79.7 ± 6.9 84.3 ± 8.0 < 0.0001
Waist circumference ≥ 90 cm 139 (10.7) 276 (20.7) 80 (7.9) 188 (19.9) < 0.0001
Systolic blood pressure (mmHg) 117.9 ± 16.1 121.3 ± 14.8 117.8 ± 14.0 121.2 ± 14.6 < 0.0001
Diastolic blood pressure (mmHg) 72.2 ± 11.8 75.0 ± 11.4 72.0 ± 10.6 75.4 ± 11.2 < 0.0001
Systolic blood pressure ≥ 130 mmHg and/or diastolic blood pressure ≥ 85 mmHg and/or medication for hypertension 294 (22.6) 395 (29.7) 227 (22.5) 281 (29.7) < 0.0001
Fasting plasma glucose (mmol/L) 5.3 ± 0.6 5.5 ± 0.7 5.3 ± 0.5 5.5 ± 0.8 < 0.0001
Fasting plasma glucose ≥ 5.6 mmol/L and/or medication for diabetes 63 (4.8) 106 (8.0) 37 (3.7) 64 (6.8) < 0.0001
HDL cholesterol (mmol/L) 1.6 ± 0.4 1.6 ± 0.4 1.7 ± 0.4 1.6 ± 0.4 < 0.0001
HDL cholesterol < 1.03 mmol/L and/or medication for dyslipidemia 74 (5.7) 102 (7.7) 41 (4.1) 67 (7.1) 0.0021
Triglycerides (mmol/L)a 1.1 ± 0.6 1.4 ± 0.9 1.0 ± 0.5 1.3 ± 0.7 < 0.0001
Triglycerides ≥ 1.7 mmol/L 124 (9.5) 341 (25.6) 68 (6.8) 199 (21.1) < 0.0001
Number of metabolic syndrome factors 0.5 ± 0.7 0.9 ± 0.8 0.4 ± 0.7 0.8 ± 0.8 < 0.0001
Prevalence of fatty liver disease 252 (19.3) 569 (42.8) 163 (16.2) 398 (42.1) < 0.0001
Total bilirubin (μmol/L) 12.0 ± 2.6 12.1 ± 2.6 22.4 ± 6.7 22.4 ± 7.1 < 0.0001
Gamma-glutamyltransferase (μkat/L) 0.3 ± 0.1 0.9 ± 0.6 0.3 ± 0.1 0.9 ± 0.8 < 0.0001
Bil/GGT ratio 39.5 ± 13.1 17.1 ± 7.4 74.6 ± 28.7 31.8 ± 16.8 < 0.0001
Incident metabolic syndrome during follow-up 79 (6.1) 199 (15.0) 42 (4.2) 140 (14.8) < 0.0001
(B) Women Total bilirubin (μmol/L) p-value
< 12.0 ≥ 12.0
Gamma-glutamyltransferase (μkat/L) Gamma-glutamyltransferase (μkat/L)
< 0.26 ≥ 0.26 < 0.26 ≥ 0.26
n 1186 1026 1125 1069  
Age (years) 43.3 ± 8.5 46.9 ± 9.1 43.3 ± 8.6 46.7 ± 9.2 < 0.0001
Follow-up interval (years) 2.8 ± 1.2 2.8 ± 1.2 2.9 ± 1.3 2.8 ± 1.2 0.2852
Body mass index (kg/m2) 20.8 ± 2.6 21.4 ± 3.3 20.2 ± 2.3 20.7 ± 3.2 < 0.0001
Current smoking 65 (5.5) 89 (8.7) 30 (2.7) 34 (3.2) < 0.0001
Exercise habit 176 (14.8) 175 (17.1) 191 (17.0) 217 (20.3) 0.0078
Waist circumference (cm) 75.2 ± 7.1 77.3 ± 8.6 74.1 ± 6.6 75.4 ± 8.1 < 0.0001
Waist circumference ≥ 80 cm 287 (24.2) 351 (34.2) 204 (18.1) 280 (26.2) < 0.0001
Systolic blood pressure (mmHg) 109.9 ± 15.1 114.6 ± 18.0 110.2 ± 15.1 114.5 ± 17.5 < 0.0001
Diastolic blood pressure (mmHg) 65.8 ± 10.3 69.8 ± 12.3 66.1 ± 10.5 69.4 ± 12.1 < 0.0001
Systolic blood pressure ≥ 130 mmHg and/or diastolic blood pressure ≥ 85 mmHg and/or medication for hypertension 116 (9.8) 204 (19.9) 124 (11.0) 201 (18.8) < 0.0001
Fasting plasma glucose (mmol/L) 5.0 ± 0.5 5.1 ± 0.4 5.0 ± 0.4 5.1 ± 0.5 < 0.0001
Fasting plasma glucose ≥ 5.6 mmol/L and/or medication for diabetes 15 (1.3) 28 (2.7) 9 (0.8) 28 (2.6) 0.0006
HDL cholesterol (mmol/L) 2.0 ± 0.4 2.0 ± 0.4 2.1 ± 0.4 2.1 ± 0.5 < 0.0001
HDL cholesterol < 1.29 mmol/L and/or medication for dyslipidemia 52 (4.4) 70 (6.8) 31 (2.8) 68 (6.4) < 0.0001
Triglycerides (mmol/L)a 0.8 ± 0.4 0.9 ± 0.4 0.7 ± 0.3 0.8 ± 0.4 < 0.0001
Triglycerides ≥ 1.7 mmol/L 37 (3.1) 47 (4.6) 15 (1.3) 34 (3.2) 0.0002
Number of metabolic syndrome factors 0.4 ± 0.6 0.7 ± 0.8 0.3 ± 0.6 0.6 ± 0.7 < 0.0001
Prevalence of fatty liver disease 66 (5.6) 180 (17.5) 47 (4.2) 111 (10.4) < 0.0001
Total bilirubin (μmol/L) 9.9 ± 1.9 10.0 ± 1.8 17.6 ± 4.8 17.8 ± 5.3 < 0.0001
Gamma-glutamyltransferase (μkat/L) 0.2 ± 0.03 0.5 ± 0.3 0.2 ± 0.03 0.5 ± 0.4 < 0.0001
Bil/GGT ratio 50.6 ± 13.6 26.7 ± 10.1 91.0 ± 32.7 47.3 ± 20.2 < 0.0001
Incident metabolic syndrome during follow-up 36 (3.0) 87 (8.5) 16 (1.4) 73 (6.8) < 0.0001
  1. Continuous variables are presented as mean ± 1 standard deviation and categorical variables are presented as number (percentage). Differences in categorical and continuous variables across the four study groups were assessed using Chi-square analysis and one-way analysis of variance, respectively
  2. HDL high-density lipoprotein, Bil/GGT ratio total bilirubin to gamma-glutamyltransferase ratio
  3. aValues were analyzed after log transformation