TABLE 1.
Concentrations of serum total, direct, and indirect bilirubin among study participants grouped by demographic characteristics and UGT1A1 genotype
| Distribution | Total bilirubin1 | Direct bilirubin1 | Indirect bilirubin1 | |
|---|---|---|---|---|
| n (%) | μmol/L | |||
| Total | 283 (100.0) | |||
| Sex2 | ||||
| Women | 142 (50.2) | 11.8 (11.1, 12.6) | 1.7 (1.6, 1.8) | 10.1 (9.5, 10.7) |
| Men | 141 (49.8) | 15.3 (14.4, 16.3) | 1.9 (1.8, 2.1) | 13.3 (12.5, 14.2) |
| Age3, y | ||||
| <30 | 199 (70.3) | 13.8 (13.1, 14.5) | 1.9 (1.8, 2.0) | 11.8 (11.2, 12.5) |
| 30+ | 84 (29.7) | 12.7 (11.8, 13.8) | 1.7 (1.6, 1.8) | 11.0 (10.1, 11.9) |
| Race2 | ||||
| Caucasian | 199 (70.3) | 13.3 (12.6, 14.0) | 1.8 (1.7, 1.9) | 11.4 (10.8, 12.1) |
| Asian | 45 (15.9) | 15.9 (14.2, 17.7) | 2.1 (1.9, 2.3) | 13.8 (12.3, 15.4) |
| Other | 33 (11.7) | 11.4 (10.0, 13.0) | 1.7 (1.5, 1.9) | 9.7 (8.5, 11.1) |
| Missing | 6 (2.1) | |||
| Physical activity, h/wk | ||||
| ≤6 | 191 (67.5) | 13.7 (13.0, 14.5) | 1.8 (1.7, 1.9) | 11.9 (11.2, 12.5) |
| >6 | 81 (28.6) | 12.8 (11.8, 13.9) | 1.8 (1.7, 1.9) | 11.0 (10.1, 11.9) |
| Missing | 11 (3.9) | |||
| UGT1A1 genotype4 | ||||
| 6/6 | 144 (50.9) | 10.7 (10.1, 11.4) | 1.5 (1.4, 1.6) | 9.2 (8.6, 9.7) |
| 6/7 | 109 (38.5) | 15.6 (14.9, 16.5) | 2.0 (1.9, 2.1) | 13.6 (12.9, 14.3) |
| 7/7 | 30 (10.6) | 23.0 (20.7, 25.4) | 2.6 (2.4, 2.9) | 20.3 (18.2, 22.6) |
1
Bilirubin data were transformed ln(x+1). Back-transformed means and 95% CI (in parentheses) are presented.
2
Significant associations with all bilirubin measures (P ≤ 0.01) after adjusting for all other variables in table using multiple linear regression.
3
Significant association with direct bilirubin concentration (P = 0.02) after adjusting for all other variables in table using multiple linear regression.
4
Significant linear associations with all bilirubin measures (P < 0.001) after adjusting for all other variables in table using multiple linear regression with grouped linear UGT1A1 genotype.