Table 2.
Association between patient characteristics and protein-bound uremic toxin concentrations at baseline.
| Characteristic | Kynurenine (µmol/L)* | Kynurenic Acid (µmol/L)* | Indoxyl Sulfate (µmol/L)* | Indole-3-Acetic Acid (µmol/L)* | p-Cresyl Sulfate tertiles† | p-Cresyl Glucuronide (µmol/L)* | Hippuric Acid (µmol/L)* |
|---|---|---|---|---|---|---|---|
| β (p) | β (p) | β (p) | eβ (p) | eβ (p) | eβ (p) | eβ (p) | |
| Age (years) | −0.003 (0.808) | −0.020 (0.020) | −0.167 (0.754) | 1.000 (0.976) | 1.010 (0.531) | 1.001 (0.895) | 1.001 (0.899) |
| Gender (male = 1) | 0.203 (0.514) | 0.356 (0.145) |
3.750 (0.802) |
1.180 (0.309) | 1.784 (0.179) | 0.668 (0.182) | 1.062 (0.726) |
| Renal creatinine clearance (mL/min/1.73m2) | −0.019 (0.514) | −0.115 (<0.001) | −6.024 (0.001) | 0.958 (0.024) | 1.002 (0.968) | 0.899 (0.004) | 0.898 (<0.001) |
| nPNA (g/kg/d) | −1.579 (0.055) | 2.367 (<0.001) | 110.055 (0.005) | 0.852 (0.687) | 4.242 (0.216) | 2.572 (0.236) | 1.891 (0.148) |
| Dialysis vintage (years) | −0.096 (0.102) | −0.003 (0.951) | −0.311 (0.914) | 0.950 (0.077) | 1.122 (0.187) | 1.082 (0.170) | 0.984 (0.613) |
| Albumin (g/L) | 0.027 (0.543) | 0.054 (0.119) |
0.019 (0.993) |
1.047 (0.072) | 1.216 (0.004) | 1.082 (0.065) | 1.019 (0.462) |
| Beta blocker (yes = 1) | 0.334 (0.282) | 0.418 (0.084) |
19.877 (0.184) | 0.976 (0.881) | 1.507 (0.341) | 0.851 (0.594) | 1.189 (0.314) |
| Calcium antagonist (yes = 1) | 0.068 (0.833) | 0.018 (0.942) |
−12.860 (0.407) | 1.122 (0.500) | 1.084 (0.855) | 0.689 (0.231) | 0.752 (0.113) |
| ACE-inhibitor (yes = 1) | −0.041 (0.901) | −0.550 (0.028) | 13.994 (0.374) | 0.724 (0.052) | 1.443 (0.458) | 1.235 (0.505) | 0.800 (0.214) |
| ARB (yes = 1) | 0.008 (0.983) |
0.653
(0.018) |
−16.456 (0.344) | 1.065 (0.727) | 0.789 (0.595) | 0.800 (0.525) | 1.337 (0.141) |
| Statin (yes = 1) | 0.039 (0.902) | 0.224 (0.359) |
3.831 (0.800) |
0.705 (0.030) | 0.908 (0.823) | 1.061 (0.845) | 0.800 (0.196) |
| Furosemide (yes = 1) | 0.440 (0.210) | −0.685 (0.011) | −14.406 (0.399) | 1.072 (0.714) | 1.770 (0.242) | 0.702 (0.301) | 1.114 (0.580) |
| Systolic blood pressure (mmHg) | 0.001 (0.857) | 0.007 (0.278) |
−0.230 (0.547) | 0.993 (0.126) | 0.988 (0.292) | 1.001 (0.862) | 1.001 (0.804) |
| Diastolic blood pressure (mmHg) | −0.004 (0.776) | 0.010 (0.401) |
0.790 (0.277) |
0.994 (0.463) | 1.016 (0.459) | 1.015 (0.319) | 1.013 (0.120) |
| Pulse pressure (mmHg) | 0.004 (0.690) | 0.006 (0.438) |
−0.650 (0.156) | 0.993 (0.165) | 0.977 (0.088) | 0.996 (0.676) | 0.997 (0.504) |
| History of CVD (yes = 1) | 0.248 (0.468) | 0.069 (0.797) |
17.557 (0.286) | 0.863 (0.407) | 1.842 (0.198) | 0.847 (0.617) | 0.724 (0.087) |
| Diabetes mellitus (yes = 1) | 0.158 (0.693) |
0.624
(0.044) |
27.092 (0.159) | 1.047 (0.843) | 1.322 (0.614) | 0.704 (0.367) | 1.492 (0.074) |
| HsCRP (mg/L) | −0.001 (0.911) | −0.010 (0.177) | 0.585 (0.216) |
0.999 (0.917) | 0.968 (0.076) | 0.994 (0.486) | 0.999 (0.898) |
ACE-inhibitor, angiotensin-converting enzyme inhibitor; ARB, angiotensin II receptor blocker; CVD, cardiovascular disease; HsCRP, high-sensitivity C-reactive protein; nPNA, normalized protein nitrogen appearance. * Multivariate linear regression analysis with adjustment for age, gender and renal creatinine clearance. Data are expressed as the unstandardized beta regression coefficient (β) with p-value, significant relations are shown in bold font. The plasma concentration of kynurenine, kynurenic acid and indoxyl sulfate will increase with β, and the plasma concentration of indole-3-acetic acid, p-cresyl glucuronide and hippuric acid, will be multiplied by eβ if the variable increases by 1 unit or if the variable changes from 0 to 1 for a dichotomous variable. † Ordinal logistic regression analysis with adjustment for age, gender and creatinine clearance for p-cresyl sulfate tertiles (tertile 1: <337 µmol/L, tertile 2: 337–701 µmol/L, tertile 3: >701 µmol/L). Data are expressed as eβ with p-value which denotes the odds of having a plasma concentration in a higher tertile if the variable increases by 1 unit or changes from 0 to 1 for a dichotomous variable. Significant associations are shown in bold font.