SUPPLEMENTAL DATA

Table 1: P-values of patient characteristics and uraemic toxin concentrations for 'younger' versus 'older' haemodialysis patients considering different cut-offs. No differences were found for none of the analyses for RRF, spKt/V, ADMA, β2M, total and free PCG, HA, IAA, and IS, and free PCS.

≤50 versus >50 / ≤60 versus >60 / ≤70 versus >70 / ≤75 versus >75 / ≤80 versus >80
Gender (male) / 0.038 ↓
DM / 0.004 ↑ / 0.029 ↑ / 0.063* ↓ / 0.049 ↓
Vintage / <0.001 ↑ / 0.003 ↑ / 0.062* ↑
BMI / 0.024 ↓
nPCR / 0.060* ↓ / 0.004 ↓
BUN / 0.072* ↓ / 0.057* ↓ / 0.031 ↓ / 0.030 ↓ / 0.011 ↓
Crea / 0.042 ↓ / 0.029 ↓ / 0.037 ↓ / 0.032 ↓
UA / 0.015 ↓ / <0.001 ↓ / 0.003 ↓ / 0.036 ↓ / <0.001 ↓
SDMA / 0.075* ↓ / 0.086* ↓
Total PCS / 0.070* ↓
Total CMPF / 0.033 ↑ / 0.013 ↑ / <0.001 ↑ / 0.036 ↑ / 0.095* ↑

DM: diabetes mellitus; BMI: body mass index; nPCR: normalised protein catabolic rate; RRF: residual renal function; spKt/V: single pool Kt/V. BUN: blood urea nitrogen; Crea: creatinine; UA: uric acid; ADMA: asymmetric dimethyl arginine; SDMA: symmetric dimethyl arginine; β2M: beta-2-microglobulin; PCG: p-cresylglucuronide; HA: hippuric acid; IAA: indole acetic acid; IS: indoxyl sulfate; PCS: p-cresylsulfate; CMPF: 3-carboxy-4-methyl-5-propyl-2-furanpropionic acid.

* Comparisons between age groups with P between 0.05 and 0.10 are marked in italics. ↓: lower in the ‘older’ group; ↑: higher in the ‘older’ group.

Table 2: P-values of patient characteristics and uraemic toxin concentrations for 'younger' versus 'older' haemodialysis patients considering different cut-offs.

mean±SD or median [25th, 75thpct] / P-value
Group 1
≤65 / Group 2
>65 & ≤77 / Group 3
>77 / 1 vs 2 vs 3 / 1 vs 2 / 2 vs 3 / 1 vs 3
BUN / 1.05±0.29 / 0.97 [0.78;1.22] / 0.89±0.31 / 0.033 / 0.097* / 0.022
Crea / 8.18±2.70 / 7.10 [5.93;8.38] / 6.80±2.05 / 0.046 / 0.015
UA / 6.73±0.98 / 6.37±1.24 / 5.99±1.18 / 0.011 / 0.002
ADMA / 1.01±0.24 / 0.91 [0.80;1.14] / 0.97±0.28
SDMA / 2.23±0.61 / 2.13±0.52 / 1.97±0.62
β2M / 36.6±16.0 / 34.8 [20.7;45.8] / 34.2±17.2
Total PCG / 0.37 [0.17;1.21] / 0.26 [0.11;0.81] / 0.56 [0.33;0.82]
Free PCG / 0.34 [0.17;1.15] / 0.25 [0.10;0.76] / 0.55 [0.27;0.77]
Total HA / 3.21 [1.77;5.95] / 2.31 [0.88;5.71] / 2.70 [1.44;5.08]
Free HA / 1.90 [0.89;3.41] / 1.27 [0.57;2.67] / 1.58 [0.86;3.03]
Total IAA / 0.24±0.15 / 0.16 [0.11;0.28] / 0.20 [0.15;0.31]
Free IAA / 0.06±0.03 / 0.06 [0.03;0.08] / 0.05 [0.04;0.07]
Total IS / 1.96±0.16 / 1.68 [1.14;2.08] / 1.61 [1.25;2.14]
Free IS / 0.10 [0.07;0.22] / 0.13 [0.06;0.20] / 0.08 [0.06;0.21]
Total PCS / 2.97±1.79 / 2.86±1.80 / 3.58±1.76 / 0.074*
Free PCS / 0.19 [0.09;0.35] / 0.15 [0.09;0.28] / 0.17 [0.12;0.26]
Total CMPF / 0.30 [0.15;0.56] / 0.47 [0.25;0.77] / 0.49 [0.36;0.95] / 0.005 / 0.051* / 0.002

SD: standard deviation; pct: percentile.

BUN: blood urea nitrogen; Crea: creatinine; UA: uric acid; ADMA: asymmetric dimethyl arginine; SDMA: symmetric dimethyl arginine; β2M: beta-2-microglobulin; PCG: p-cresylglucuronide; HA: hippuric acid; IAA: indole acetic acid; IS: indoxyl sulfate; PCS: p-cresylsulfate; CMPF: 3-carboxy-4-methyl-5-propyl-2-furanpropionic acid.

* Comparisons between age groups with P between 0.05 and 0.10 are marked in italics.

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