Table 6. Factors associated with serum total indoxyl sulfate levels.
| Variable | Units | Univariate Correlation (correlation coefficient) | p | Multiple regression analysis (standardized coefficients; Beta) | p |
| Age | 1 year | 0.001 | 0.988 | - | - |
| Male vs female | - | 0.153 | 0.029** | - | - |
| Smoking (yes vs no) | - | 0.072 | 0.319 | - | - |
| diabetes (yes vs no) | - | −0.096 | 0.182 | - | - |
| CAD (yes vs no) | - | 0.132 | 0.067* | - | - |
| CHF (yes vs no) | - | −0.048 | 0.507 | - | - |
| PAOD (yes vs no) | - | −0.005 | 0.944 | - | - |
| COPD (yes vs no) | - | −0.331 | 0.669 | - | - |
| Stroke (yes vs no) | - | −0.080 | 0.264 | - | - |
| Cancer (yes vs no) | - | −0.090 | 0.210 | - | - |
| Dialysis vintage | 1 month | −0.032 | 0.647 | - | - |
| Body mass index | 1 kg/m2 | 0.005 | 0.940 | - | - |
| nPCR | 1 g/kg/day | 0.014 | 0.852 | - | - |
| CT ratio | 1% | −0.072 | 0.345 | - | - |
| BUN | 1 mg/dL | 0.143 | 0.041** | - | - |
| Creatinine | 1 mg/dL | 0.311 | <0.001*** | 0.285 | <0.001*** |
| Hemoglobin | 1 g/dL | 0.127 | 0.070* | - | - |
| Albumin | 1 g/dL | 0.119 | 0.091* | - | - |
| hs-CRP | 1 mg/L | −0.139 | 0.050* | - | - |
| Calcium | 1 mg/dL | 0.027 | 0.701 | - | - |
| Phosphate | 1 mg/dL | 0.026 | 0.713 | - | - |
| i-PTH | 1 pg/mL | 0.083 | 0.239 | - | - |
| IL-1β | 1 ng/L | 0.013 | 0.859 | - | - |
| IL-6 | 1 ng/L | −0.062 | 0.498 | - | - |
| TNF-α | 1 ng/L | −0.062 | 0.392 | - | - |
| Total PCS | 1 mg/L | 0.292 | <0.001 *** | 0.239 | 0.001*** |
| Kt/V | −0.031 | 0.674 | - | - | |
| URR | 1% | 0.003 | 0.969 | - | - |
| Synthetic membrane use (yes vs no) | - | 0.195 | <0.001*** | 0.139 | 0.046* |
| High Flux dialysis (yes vs no) | - | 0.159 | <0.001*** | - | - |
Abbreviations: CAD, coronary artery disease; CHF, congestive heart failure; PAOD, peripheral arterial occlusive disease; COPD, chronic obstructive pulmonary disease; nPCR, normalized protein catabolic rate; CT ratio, cardiothoracic ratio; BUN, blood urea nitrogen; hs-CRP, high sensitive C- reactive protein; i-PTH, intact parathyroid hormone; IL-1β, interleukin - 1 beta; IL-6, interleukin 6; TNF-alpha, tumor necrosis factor-alpha; PCS, p-cresol sulfate; URR, urea reduction rate.
*: p value<0.1.
**: p value<0.05.
***: p value<0.01.