Table 2. Hazard ratios (95% confidence intervals) for incident chronic kidney disease by serum bilirubin quartiles.
| Person-years | No. of incident cases | Age-adjusted HR(95% CI) | Multivariate HR (95% CI) | Multivariate HR (95% CI), time-dependent model* | ||
| Model 1 | Model 2 | |||||
| Total bilirubin | ||||||
| <0.9 mg/dl | 18,018.4 | 59 | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) |
| 0.9–1.1 mg/dl | 23,078.0 | 820 | 1.02 (0.73–1.43) | 1.01 (0.72–1.41) | 1.05 (0.73–1.49) | 1.29 (0.82–2.04) |
| 1.2–1.4 mg/dl | 15,405.5 | 56 | 1.12 (0.78–1.61) | 1.11 (0.77–1.60) | 1.11 (0.74–1.65) | 1.00 (0.62–1.60) |
| ≥1.5 mg/dl | 14,013.8 | 41 | 0.92 (0.62–1.38) | 0.91 (0.61–1.36) | 1.03 (0.67–1.59) | 0.90 (0.51–1.58) |
| P for trend | 0.89 | 0.84 | 0.79 | 0.56 | ||
| Direct bilirubin | ||||||
| <0.31 mg/dl | 25,992.4 | 103 | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) |
| 0.31–0.40 mg/dl | 15,787.3 | 58 | 0.93 (0.67–1.28) | 0.93 (0.67–1.29) | 0.93 (0.66–1.30) | 0.85 (0.56–1.28) |
| 0.41–0.50 mg/dl | 11,687.4 | 38 | 0.88 (0.60–1.27) | 0.88 (0.60–1.28) | 0.66 (0.43–1.01) | 0.59 (0.33–1.03) |
| ≥0.51 mg/dl | 17,048.8 | 39 | 0.60 (0.42–0.88) | 0.60 (0.41–0.87) | 0.66 (0.45–0.98) | 0.43 (0.20–0.93) |
| P for trend | 0.01 | 0.01 | 0.02 | 0.02 | ||
| Indirect bilirubin | ||||||
| <0.53 mg/dl | 17,653.7 | 53 | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) |
| 0.53–0.7 mg/dl | 23,370.5 | 76 | 1.03 (0.73–1.46) | 1.03 (0.72–1.46) | 0.94 (0.65–1.36) | 1.00 (0.61–1.63) |
| 0.71–0.87 mg/dl | 11,851.3 | 47 | 1.29 (0.87–1.91) | 1.26 (0.85–1.87) | 1.07 (0.71–1.62) | 1.07 (0.65–1.75) |
| ≥0.88 mg/dl | 17,640.3 | 62 | 1.21 (0.84–1.75) | 1.20 (0.83–1.74) | 1.12 (0.76–1.66) | 0.80 (0.47–1.36) |
| P for trend | 0.18 | 0.17 | 0.44 | 0.46 | ||
Model 1: Adjusted for age, smoking, alcohol intake and exercise.
Model 2: Further adjusted for eGFR, CRP, AST, ALT, GGT and metabolic syndrome traits (high glucose, high blood pressure, low HDL cholesterol, high triglycerides and high BMI).
*estimated from pooled logistic regression models with serum bilirubin quartiles as time-dependent categorical variable s adjusted for other covariates (age, smoking, alcohol intake, exercise, eGFR, CRP, AST, ALT, GGT and each metabolic syndrome trait) over time as time-dependent variables.
Abbreviations: CI, confidence interval; eGFR: estimated glomerular filtration rate; HDL, high-density lipoprotein; HR, hazard ratio; LDL, low-density lipoprotein; ALT: alanine aminotransferase; AST: aspartate aminotransferase; GGT: gamma-glutamyltransferase.