Potential Cardiovascular Risk Protection of Bilirubin in End-Stage Renal Disease Patients under Hemodialysis

Table 1

Results of studied variables (sociodemographic data and dialysis adequacy, UGT1A1 genotype, hematological data, iron metabolism, lipid profile, and inflammatory markers) by tertiles of bilirubin.

	All patients; ()	Tertiles of total bilirubin
		T1; TB: <0.21 mg/dL; ()	T2; TB: 0.21 to 0.3 mg/dL; ()	T3; TB: >0.3 mg/dL; ()	value^b	value^c
Sociodemographic data and dialysis adequacy
Age, years	66.1 ± 14.0	67.7 ± 13.6	65.5 ± 15.5	65.1 ± 13.0	0.511	—
Gender (male), (%)	105 (55)	33 (49.3)	31 (50.8)	41 (65.1)	0.142	—
Kt/V urea	1.5 ± 0.3	1.5 ± 0.4	1.5 ± 0.2	1.4 ± 0.2	0.360	0.362
Creatinine, mg/dL	8.1 ± 2.8	7.7 ± 2.4	8.2 ± 2.6	8.5 ± 3.3	0.306	0.407
Urea reduction ratio, %	76.0 ± 6.6	76.2 ± 7.6	76.8 ± 6.2	75.1 ± 5.6	0.377	0.382
Dose of darbepoetin-, g/kg/week	0.4 (0.2–0.7)	0.5 (0.3–0.8)	0.4 (0.2–0.6)	0.5 (0.2–0.9)	0.311	0.335
Central venous catheter use, (%)	44 (23.0)	20 (29.9)	14 (23.0)	10 (15.9)	0.167	—
BMI, kg/m^2	25.9 ± 4.6	26.3 ± 5.4	26.1 ± 4.1	25.3 ± 4.2	0.370	0.421
UGT1A1 genotype
6/6, (%)	94 (49.2)	33 (49.3)	35 (57.4)	26 (41.3)	0.236	—
6/7, (%)	81 (42.4)	31 (46.3)	20 (32.8)	30 (47.6)
7/7, (%)	16 (8.4)	3 (4.5)	6 (9.8)	7 (11.1)
Hematological data
Hemoglobin, g/dL	11.7 ± 1.4	11.4 ± 1.5		11.8 ± 1.3	0.042	0.041
Hematocrit, %	36.4 ± 4.6	35.3 ± 4.5		36.6 ± 4.3	0.026	0.022
Erythrocytes, ×10^12/L	3.8 ± 0.5	3.7 ± 0.5		3.8 ± 0.5	0.043	0.042
Reticulocytes, ×10^9/L	49.3 (27.4–72.8)	56.0 (28.5–75.6)	40.1 (28.3–66.8)	50.8 (26.2–74.7)	0.318	0.325
RPI	0.9 (0.5–1.4)	0.9 (0.5–1.3)	0.8 (0.5–1.4)	1.1 (0.5–1.5)	0.834	0.830
Platelets, ×10^9/L	183.7 ± 55.1	197.7 ± 59.9	175.8 ± 43.6		0.027	0.040
White blood cells, ×10^9/L	6.4 ± 2.0	6.9 ± 2.0	6.3 ± 2.0		0.046	0.057
Neutrophils, ×10^9/L	4.0 ± 1.5	4.2 ± 1.3	3.8 ± 1.6	3.8 ± 1.6	0.247	0.287
Lymphocytes, ×10^9/L	1.7 ± 0.7	1.8 ± 0.9	1.7 ± 0.6		0.011	0.011
Neutrophil/lymphocyte ratio	2.3 (1.8–3.3)	2.3 (1.8–3.4)	2.2 (1.5–3.0)	2.5 (2.0–3.3)	0.119	0.120
Iron metabolism
Iron, mg/dL	38.0 (30.0–54.0)	36.0 (29.0–43.0)	41.0 (29.0–55.0)	44.0 (32.0–56.0)^a	0.005	0.006
Transferrin, mg/dL	184.3 ± 35.6	193.3 ± 34.6	182.4 ± 39.4		0.023	0.024
Transferrin saturation, %	17.7 ± 10.8	13.9 ± 6.2	17.7 ± 9.4		<0.001	<0.001
sTfR, nmol/L	23.3 ± 11.9	21.7 ± 9.4	25.0 ± 14.2	23.4 ± 11.7	0.281	0.284
Ferritin, ng/mL	402.0 ± 152.6	369.3 ± 153.9	419.4 ± 162.7	419.8 ± 137.0	0.093	0.090
Hepcidin-25, ng/mL	1599.1; (863.6–2409.0)	1738.0; (1144.3–2637.7)	1649.8; (931.7–2440.1)	1476.6; (537.8–2350.0)	0.108	0.101
Lipid profile
Total cholesterol, mg/dL	154.4 ± 43.4	156.7 ± 34.6	151.3 ± 35.1	155.0 ± 57.3	0.777	0.796
Triglyceride, mg/dL	119.0 (91.0–176.0)	135.0 (91.0–183.0)	113.0 (96.5–172.5)	109.0 (85.0–151.0)	0.156	0.103
HDL-cholesterol, mg/dL	42.3 ± 13.5	41.7 ± 12.1	42.5 ± 13.6	42.7 ± 14.9	0.908	0.888
LDL-cholesterol, mg/dL	73.5 ± 29.5	73.8 ± 28.5	73.2 ± 28.0	73.4 ± 32.2	0.992	0.999
ox-LDL, U/L	36.0 ± 15.4	39.8 ± 21.3	34.5 ± 8.6		0.033	0.041
ox-LDL/LDL-c ratio, U/mg	0.053 ± 0.019	0.058 ± 0.025			0.007	0.005
Lp(a), mg/dL	45.4 (25.2–88.1)	50.4 (27.3–106.2)	45.4 (24.1–89.1)	37.4 (24.7–68.2)^a	0.052	0.071
Apo A, mg/dL	123.1 ± 30.5	128.9 ± 32.4	125.7 ± 32.7		0.017	0.013
Apo B, mg/dL	72.8 ± 21.8	81.8 ± 21.3			<0.001	<0.001
Apo A/Apo B ratio	1.83 ± 0.67	1.68 ± 0.54	1.89 ± 0.74		0.048	0.054
Inflammatory markers
Adiponectin, mg/L	9.2 ± 4.7	7.9 ± 3.7	9.1 ± 4.6		0.003	0.004
PON1, nmol p nitrofenol/mL/min	398.3 ± 92.6	376.0 ± 70.1	398.5 ± 92.9		0.040	0.033
CRP, mg/dL	5.2 (2.3–13.3)	7.1 (3.2–14.6)	4.9 (2.1–13.5)	3.6 (1.9–12.7)	0.393	0.453
IL-6, pg/mL	2.3 (1.4–4.3)	3.1 (2.1–5.4)	2.1 (1.4–4.0)^a	1.6 (1.1–3.4)^a	0.001	0.003
Albumin, g/dL	3.9 ± 0.4	3.9 ± 0.3	3.9 ± 0.4	3.9 ± 0.4	0.936	0.976

value < 0.05 for post hoc test considering T1 as reference category; ^bANOVA analysis for continuous covariates and Chi-squared test or Fisher’s exact test for categorical covariates. ^cAdjusting for age (ANCOVA). BMI: body mass index; RPI: reticulocyte production index; sTfR: soluble transferrin receptor; HDL: high-density lipoprotein; LDL: low-density lipoprotein; ox-LDL: oxidized low-density lipoprotein; Lp(a): lipoprotein (a); Apo A: apolipoprotein A; Apo B: apolipoprotein B; PON1: paraoxonase 1; CRP: C-reactive protein; IL-6: interleukin-6.