Table 4.
Predictors of Total Solutes in 1273 Patients of the HEMO Study
| Total PCS (mg/dL) | Total IS (mg/dL) | Total HIPP (mg/dL) | Total PAG (mg/dL) | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Mean (SD) = 3.3 (1.7) | Mean (SD) = 2.5 (1.2) | Mean (SD) = 5.4 (4.3) | Mean (SD) = 4.5 (2.8) | ||||||||||||||
| Median [IQR] = 3.3 [2.2–4.4] | Median [IQR] = 2.4 [1.7–3.3] | Median [IQR] = 4.5 [2.3–7.4] | Median [IQR] = 4.0 [2.5–6.0] | ||||||||||||||
| Univariate | Multivariable | Univariate | Multivariable | Univariate | Multivariable | Univariate | Multivariable | ||||||||||
| Characteristics | Modeling | β (SE) | p | β (SE) | p | β (SE) | p | β (SE) | p | β (SE) | p | β (SE) | p | β (SE) | p | β (SE) | p |
| Demographic | |||||||||||||||||
| Age, years | Per 10 year higher | 0.066 (0.034) | 0.06 | — | — | −0.094 (0.024) | <.001 | — | — | −0.247 (0.085) | 0.004 | — | — | 0.051 (0.057) | 0.4 | 0.165 (0.054) | 0.002 |
| Sex, Female % | Female vs. Male | 0.051 (0.097) | 0.6 | — | — | −0.319 (0.068) | <.001 | −0.180 (0.064) | 0.005 | −0.345 (0.241) | 0.2 | — | — | 0.215 (0.161) | 0.2 | 0.350 (0.147) | 0.02 |
| Race, Black % | Black vs. Non-Black | 0.211 (0.099) | 0.03 | 0.296 (0.095) | 0.002 | 0.079 (0.070) | 0.3 | — | — | −0.840 (0.246) | <.001 | −0.879 (0.239) | <.001 | −0.064 (0.165) | 0.7 | — | — |
| Clinical Characteristics | |||||||||||||||||
| Diabetes, % | Yes vs. No | 0.604 (0.095) | <.001 | 0.695 (0.096) | <.001 | −0.342 (0.068) | <.001 | — | — | −0.667 (0.240) | 0.005 | — | — | 0.591 (0.159) | <.001 | 0.833 (0.155) | <.001 |
| Cardiac Disease, % | Yes vs. No | 0.012 (0.117) | 0.9 | — | — | −0.168 (0.083) | 0.04 | — | — | −0.730 (0.292) | 0.01 | — | — | 0.137 (0.195) | 0.5 | — | — |
| ICED Score, % | <3 vs. 3 | −0.016 (0.102) | 0.9 | — | — | −0.255 (0.072) | <.001 | — | — | −0.370 (0.255) | 0.1 | — | — | 0.379 (0.170) | 0.03 | — | — |
| Gastrointestinal Disease, % | Yes vs. No | −0.000 (0.099) | 0.9 | — | — | −0.212 (0.070) | 0.002 | — | — | −0.061 (0.247) | 0.8 | — | — | 0.378 (0.164) | 0.02 | 0.436 (0.151) | 0.004 |
| Residual Kidney Urea Clearance, ml/min/35L TBW | Per 0.5 mL/min/35 L TBW higher | 0.074 (0.049) | 0.1 | — | — | −0.197 (0.034) | <.001 | −0.130 (0.033) | <.001 | −0.852 (0.119) | <.001 | −0.599 (0.121) | <.001 | −0.473 (0.080) | <.001 | −0.246 (0.076) | 0.001 |
| Body Mass Index, Kg/m2 3 | ≥25 Kg/m2 vs. <25 Kg/m2 | 0.066 (0.096) | 0.5 | — | — | −0.088 (0.068) | 0.2 | — | — | −0.230 (0.239) | 0.3 | — | — | −0.175 (0.160) | 0.3 | −0.319 (0.150) | 0.03 |
| Body Surface Area, m2 3 | Per 0.5 m2 higher | 0.218 (0.121) | 0.07 | — | — | 0.169 (0.086) | 0.05 | — | — | −0.185 (0.303) | 0.5 | — | — | −0.118 (0.201) | 0.6 | — | — |
| Dialysis Characteristics | |||||||||||||||||
| Years of prior dialysis | Per 1 year higher | −0.054 (0.011) | <.001 | −0.038 (0.011) | 0.001 | 0.037 (0.008) | <.001 | — | — | 0.141 (0.029) | <.001 | — | — | 0.039 (0.019) | 0.04 | — | — |
| Predialysis Systolic Blood Pressure, mm Hg 3 | Per 10 mm Hg higher | 0.034 (0.019) | 0.07 | — | — | −0.000 (0.013) | 0.9 | — | — | −0.010 (0.046) | 0.8 | — | — | 0.070 (0.031) | 0.02 | — | — |
| Post Dialysis Weight, Kg † | Per 10 kg higher | 0.048 (0.031) | 0.1 | — | — | 0.024 (0.022) | 0.3 | — | — | −0.049 (0.078) | 0.5 | — | — | −0.050 (0.052) | 0.3 | — | — |
| Relative Volume Removed, % † | Per 1% higher | −0.016 (0.028) | 0.6 | −0.098 (0.028) | <.001 | 0.023 (0.020) | 0.2 | — | — | 0.412 (0.070) | <.001 | 0.222 (0.070) | 0.002 | 0.139 (0.047) | 0.003 | — | — |
| Dose Intervention | High Dose vs. Standard Dose | 0.061 (0.096) | 0.5 | 0.358 (0.107) | <.001 | −0.303 (0.068) | <.001 | — | — | −0.217 (0.239) | 0.4 | — | — | −0.318 (0.159) | 0.05 | — | — |
| Flux Intervention | High Flux vs. Low Flux | −0.030 (0.096) | 0.8 | — | — | −0.075 (0.068) | 0.3 | — | — | −0.287 (0.239) | 0.2 | — | — | −0.339 (0.159) | 0.03 | — | — |
| Treatment Time, min † | Per 30 minute higher | −0.010 (0.051) | 0.9 | −0.114 (0.056) | 0.04 | −0.060 (0.036) | 0.1 | — | — | −0.106 (0.127) | 0.4 | — | — | −0.131 (0.085) | 0.1 | — | — |
| Blood Flow Rate, ml/min † | Per 50 ml/min higher | 0.064 (0.039) | 0.1 | — | — | −0.029 (0.028) | 0.3 | — | — | −0.119 (0.098) | 0.2 | — | — | −0.191 (0.066) | 0.004 | — | — |
| Dialysate Flow Rate, ml/min † | Per 100 ml/min higher | −0.012 (0.037) | 0.7 | — | — | −0.047 (0.026) | 0.08 | — | — | −0.028 (0.092) | 0.8 | — | — | −0.079 (0.062) | 0.2 | — | — |
| Predialysis Laboratory Tests | |||||||||||||||||
| Blood Urea Nitrogen, mg/dL † | Per 10 mg/dL higher | 0.224 (0.025) | <.001 | 0.235 (0.026) | <.001 | 0.211 (0.017) | <.001 | 0.176 (0.017) | <.001 | 0.489 (0.062) | <.001 | 0.358 (0.063) | <.001 | 0.460 (0.041) | <.001 | 0.471 (0.038) | <.001 |
| Single-pool Kt/VUREA† | Per 0.2 higher | 0.016 (0.035) | 0.6 | — | — | −0.082 (0.024) | <.001 | — | — | 0.005 (0.087) | 0.9 | — | — | −0.031 (0.057) | 0.6 | — | — |
| Serum albumin, g/dL† | Per 0.5 g/dL higher | 0.344 (0.061) | <.001 | 0.362 (0.061) | <.001 | 0.427 (0.043) | <.001 | 0.331 (0.041) | <.001 | 0.962 (0.153) | <.001 | 0.721 (0.150) | <.001 | 0.070 (0.104) | 0.5 | — | — |
| Serum β2-microglobulin, mg/L † | Per 10 mg/L higher | −0.080 (0.034) | 0.02 | — | — | 0.208 (0.024) | <.001 | 0.163 (0.023) | <.001 | 0.695 (0.084) | <.001 | 0.553 (0.084) | <.001 | 0.465 (0.056) | <.001 | 0.486 (0.054) | <.001 |
| Nutritional Data | |||||||||||||||||
| Equilibrated nPCR, g/kg/day † | Per 0.2 g/kg/day higher | 0.299 (0.036) | <.001 | — | — | 0.241 (0.025) | <.001 | — | — | 0.665 (0.090) | <.001 | — | — | 0.597 (0.058) | <.001 | — | — |
| Adjusted protein intake, g/kg/day (ABW)* | Per 10 g/kg/day higher | −1.208 (1.378) | 0.38 | — | — | 1.379 (0.980) | 0.16 | — | — | 2.351 (3.442) | 0.49 | — | — | 1.115 (2.297) | 0.63 | — | — |
| Fat, % | Per 10% higher | 0.047 (0.063) | 0.46 | — | — | −0.009 (0.045) | 0.85 | — | — | −0.434 (0.156) | 0.005 | — | — | 0.081 (0.104) | 0.44 | — | — |
| Carbohydrate, % | Per 10% higher | −0.102 (0.051) | 0.05 | — | — | 0.012 (0.037) | 0.75 | — | — | 0.528 (0.128) | <.001 | 0.472 (0.124) | <.001 | −0.092 (0.086) | 0.28 | — | — |
| Multivariable Model Characteristics | |||||||||||||||||
| Root mean square error (RMSE) | — | — | — | 2.48 | — | — | — | 1.15 | — | — | — | 15.52 | — | — | — | 6.15 | — |
| R2 | — | — | — | 14.9% | — | — | — | 22.2% | — | — | — | 15.9% | — | — | — | 20.3% | — |
Abbreviations: PCS, P-cresol Sulfate; IS, Indoxyl Sulfate, HIPP, Hippurate; PAG, Phenylacetylglutamine; SE, Standard Error; ICED, Index of Coexistent Disease; Equilibrated nPCR, equilibrated normalized protein catabolic rate; TBW, total body water; ABW, adjusted body weight
Note: βcoefficients are from linear regression of PCS, IS, HIPP or PAG (natural scale) on predictors in separate models (univariate associations) and in a forward selection model with model entry specified as p≤0.05 (multivariable model). Interpretation of β coefficients: change in value of solute per modeled change in predictor. Positive values mean higher solute concentration and negative values mean lower solute concentration.
†
Measured at the same time as solutes. Remaining variables are measured at baseline.
*
If body weight was <90% or >120% of median standard body weight (SBW) as determined from the National Health and Nutrition Examination Survey II (NHANES II) data then protein intakes were normalized to an adjusted body weight (ABW) to standardize nutrient intake using the formula: ABW = ([Actual weight - SBW)] × 0.25) + SBW.26