Table 1.
Baseline characteristics of study patients who had different serum aluminum levels (n=901)
| Characteristics | First quartile (SAL <6 μg/L) (n=222) | Second quartile (SAL: 6–9 μg/L) (n=229) | Third quartile (SAL: 9–13 µg/L) (n=230) | Fourth quartile (SAL >13 μg/L) (n=220) | P-value |
|---|---|---|---|---|---|
| Demographics | |||||
| Age (years) | 56.0±13.6 | 55.3±13.9 | 55.3±13.6 | 58.4±13.1 | 0.080 |
| Gender (female) | 94 (41.8) | 109 (50.4) | 119 (52.8) | 114 (51.4) | 0.058 |
| Body mass index (kg/m2) | 22.1±3.3 | 22.0±2.8 | 22.2±3.3 | 22.3±3.3 | 0.377 |
| Smoking | 45 (20.9) | 32 (14.6) | 41 (17.4) | 38 (17.9) | 0.623 |
| Comorbidities | |||||
| Previous CVDs | 12 (5.3) | 14 (6.2) | 11 (4.7) | 6 (2.8) | 0.111 |
| Hypertension | 86 (38.7) | 89 (40.3) | 78 (33.6) | 97 (44.5) | 0.539 |
| Diabetes mellitus | 52 (23.1) | 44 (19.9) | 47 (20.4) | 56 (24.8) | 0.621 |
| Dialysis-related data | |||||
| HD duration (years) | 5.7±4.8 | 6.4±5.2 | 6.9±5.3 | 7.4±5.6 | 0.001 |
| Use of fistula | 182 (82.2) | 174 (79.2) | 187 (81.7) | 170 (77.5) | 0.313 |
| Use of BCM dialyzers | 169 (76.0) | 154 (70.8) | 170 (74.0) | 162 (73.9) | 0.769 |
| Erythropoietin use | 210 (94.7) | 199 (91.2) | 213 (92.8) | 200 (89.9) | 0.243 |
| Calcitriol use | 13 (6.2) | 17 (8.0) | 38 (17.0) | 50 (22.9) | <0.001 |
| Erythropoietin (U/kg/wk) | 76.7±44.7 | 71.3±49.2 | 73.2±46.4 | 76.7±45.4 | 0.909 |
| Kt/V (Daugirdas) urea | 1.75±0.33 | 1.81±0.31 | 1.83±0.32 | 1.81±0.33 | 0.143 |
| nPCR (g/kg/d) | 1.16±0.26 | 1.17±0.26 | 1.19±0.26 | 1.19±0.28 | 0.231 |
| Residual daily urine >100 mL/d | 55 (25.3) | 40 (17.7) | 52 (23.0) | 45 (20.6) | 0.542 |
| Biochemical data | |||||
| Hemoglobin (g/dL) | 10.5±1.1 | 10.7±1.5 | 10.5±1.4 | 10.4±1.3 | 0.159 |
| Albumin (g/dL) | 4.11±0.33 | 4.07±0.35 | 4.08±0.35 | 4.02±0.37 | 0.021 |
| Creatinine (mg/dL) | 11.1±2.4 | 11.0±2.4 | 10.9±2.4 | 10.4±2.2 | 0.008 |
| Transferrin saturation (%) | 29.7±11.0 | 30.2±13.7 | 28.5±12.1 | 29.5±11.2 | 0.540 |
| Ferritin (µg/L) | 318.4 (8.7–1,454.6) | 300.0 (10.9–3,571.2) | 299.1 (9.3–4,658.8) | 323.5 (6.6–1,641.8) | 0.467 |
| Corrected-calcium (mg/dL) | 9.7±0.8 | 9.9±0.9 | 9.8±0.9 | 9.9±1.0 | 0.263 |
| Phosphate (mg/dL) | 4.8±1.4 | 4.8±1.3 | 4.8±1.4 | 4.5±1.3 | 0.020 |
| iPTH (pg/mL) | 138.4 (0.20–1,473.7) | 109.4 (0.20–1,754.0) | 105.1 (0.3–1,655.4) | 127.0 (0.7–1,574.2) | 0.858 |
| Cardiovascular risks | |||||
| HDL-C (mg/dL) | 43.6±14.3 | 46.0±13.6 | 45.0±14.3 | 45.5±16.4 | 0.285 |
| LDL-C (mg/dL) | 93.5±29.7 | 98.7±29.6 | 95.2±29.9 | 92.4±31.5 | 0.458 |
| hsCRP (mg/L) | 2.62 (0.20–63.45) | 3.01 (0.32–70.88) | 2.70 (0.20–49.40) | 3.13 (0.21–73.21) | 0.668 |
| Cardiothoracic ratio (%) | 49.8±6.9 | 49.6±6.7 | 49.6±7.4 | 50.1±6.8 | 0.626 |
Notes: Data are presented as means ± SDs, numbers (percentages), or medians (minimum, maximum). Significance was assessed by ANOVA test or Chi-square test. A P-value of <0.05 was considered statistically significant. Previous CVD includes cerebrovascular disease, coronary arterial disease, congestive heart failure, or peripheral vascular disease. Hypertension was defined as; blood pressure ≥140/90 mmHg based on at least two measurements or regular use of an antihypertensive drug. Diabetes mellitus was diagnosed by a physician previously or by two measurements of fasting glucose of 126 mg/dL or more.
Abbreviations: BCM, biocompatible membrane; CVD, cardiovascular disease; HD, hemodialysis; HDL, high-density lipoprotein; hsCRP, high sensitivity C-reactive protein; iPTH, intact parathyroid hormone; LDL, low-density lipoprotein; nPCR, normalized protein catabolic rate; SAL, serum aluminum level; SD, standard deviation.