Table 1.
Clinical characteristics of the study population according to serum bilirubin quartiles.
| Serum bilirubin quartiles (mg/dL) | ||||||
|---|---|---|---|---|---|---|
| Q1 (≤ 0.7) | Q2 (0.8–0.9) | Q3 (1.0–1.1) | Q4 (≥ 1.2) | P value | Post hoc | |
| n | 275 | 356 | 302 | 351 | ||
| Age (years) | 57.3 (8.1) | 56.4 (7.3) | 54.7 (7.1) | 55.2 (7.3) | 0.001 | b,c,d |
| Body mass index (kg/m2) | 24.9 (2.6) | 24.6 (2.5) | 24.6 (2.5) | 24.4 (2.5) | 0.197 | |
| Systolic BP (mmHg) | 126.4 (15.0) | 127.3 (15.2) | 127.2 (17.0) | 127.4 (16.8) | 0.859 | |
| Diastolic BP (mmHg) | 78.9 (8.9) | 79.6 (8.7) | 80.2 (9.8) | 79.8 (9.6) | 0.339 | |
| Mean arterial pressure (mmHg) | 94.7 (10.4) | 95.6 (10.3) | 95.9 (11.5) | 95.7 (11.5) | 0.577 | |
| Hemoglobin (g/dL) | 15.0 (0.9) | 15.1 (1.0) | 15.4 (1.1) | 15.6 (1.0) | < 0.001 | b,c,d,e |
| Hematocrit (%) | 44.2 (2.6) | 44.5 (2.8) | 45.0 (3.1) | 45.3 (3.0) | < 0.001 | b,c,e |
| Fasting glucose (mg/dL) | 105.6 (27.0) | 102.8 (23.3) | 100.6 (22.3) | 99.5 (17.1) | 0.006 | b,c, |
| Triglyceride (mg/dL) | 127 (93–175) | 113 (81–158) | 112 (85–169) | 109 (80–149) | 0.014 | c |
| HDL-cholesterol (mg/dL) | 44.0 (10.9) | 47.1 (11.2) | 47.4 (11.6) | 48.4 (10.8) | < 0.001 | a,b,c |
| Aspartate aminotransferase (U/L) | 22 (18–26) | 22 (19–26) | 22 (18–27) | 22 (19–26) | 0.963 | |
| Alanine aminotransferase (U/L) | 23 (18–32) | 23 (19–32) | 24 (18–33) | 22 (18–30) | 0.703 | |
| Leukocyte (cells/μL) | 6590 (1740) | 6217 (1801) | 6019 (1571) | 5984 (1674) | < 0.001 | a,b,c |
| Current smoking (%) | 43.6 | 31.7 | 28.7 | 22.1 | < 0.001 | b,c,d |
| Alcohol drinking (%)g | 45.6 | 52.2 | 53.5 | 44.5 | 0.053 | |
| Regular exercise (%)h | 40.5 | 43.1 | 42.8 | 45.8 | 0.632 | |
| Hypertension (%)i | 45.5 | 46.9 | 43.4 | 40.5 | 0.348 | |
| Type 2 diabetes (%)j | 17.8 | 14.6 | 11.1 | 10.9 | 0.042 | c |
| Dyslipidemia (%)k | 35.6 | 30.4 | 28.8 | 24.4 | 0.024 | c |
| Metabolic syndrome (%) | 40.3 | 36.8 | 32.1 | 30.2 | < 0.001 | b,c |
BP blood pressure, HDL high density lipoprotein, NA not applicable. Data are expressed as the mean (SD), median (IQR), or percentage. P-values were calculated using 1-way ANOVA test, Kruskal–Wallis test, or chi-square test. The differences of mean, median and proportion between groups were determined using post hoc analysis of ANOVA, Kruskal–Wallis test and chi-squared test using Bonferroni corrections.
aQ1 versus Q2, bQ1 versus Q3, cQ1 versus Q4, dQ2 versus Q3, eQ2 versus Q4, fQ3 versus Q4, gAlcohol drinking ≥ twice/week. hRegular exercise ≥ three times/week. iHypertension was defined as a systolic blood pressure ≥ 140 mmHg, diastolic blood pressure ≥ 90 mmHg, or the current use of hypertension medication. jType 2 diabetes was defined as a fasting plasma glucose ≥ 126 mg/dL or the current use of diabetes medication. kDyslipidemia was defined as triglyceride ≥ 150 mg/dL or HDL-cholesterol < 40 mg/dL for men or the current use of dyslipidemia medications.