Table 1. Clinical characteristics of patients at baseline and during follow-up stratified for iron supplementation during follow-up.
| All patients | Iron supplementation | No iron supplementation | |
| (n = 235) | (n = 204) | (n = 31) | |
| Sex | |||
| Male, n (%) | 146 (62.1%) | 126 (61.8%) | 20 (64.5%) |
| Female, n (%) | 89 (37.9%) | 78 (38.2%) | 11 (35.5%) |
| Age (years) | 61.7±14.0 | 61.7±13.7 | 62.0±16.0 |
| Body Mass Index (kg/m2) | 26.1±4.5 | 26.2±4.6 | 25.2±3.8 |
| Start of dialysis with | |||
| Hemodialysis, n (%) | 197 (83.8%) | 181 (88.7%) | 16 (51.6%) d |
| Peritoneal dialysis, n (%) | 38 (16.2%) | 23 (11.3%) | 15 (48.4%) d |
| Year of start of dialysis | |||
| 2000–2003 | 122 (51.9%) | 106 (52.0%) | 16 (51.6%) |
| 2004–2006 | 113 (48.1%) | 98 (48.0%) | 15 (48.4%) |
| Diabetes mellitus, n (%) | 82 (34.9%) | 77 (37.7%) | 5 (16.1%) a |
| Systolic blood pressure (mmHg) | 154.0±22.7 | 153.9±22.6 | 154.6±23.5 |
| Diastolic blood pressure (mmHg) | 83.0±12.3 | 82.7±12.6 | 82.9±11.9 |
| [78.0; 84.0; 90.0] | [77.0; 83.0; 90.0] | [78.0; 85.0; 91.0] | |
| Medication at baseline | |||
| ESA, n (%) | 183 (77.9%) | 164 (80.4%) | 19 (61.3%) a |
| Iron supplements, n (%) | 53 (22.6%) | 53 (26.0%) | 0 (0.0%) c |
| ESA and iron supplements, n (%) | 51 (21.7%) | 51 (25.0%) | 0 (0.0%) c |
| Laboratory parameters at baseline | |||
| Ferritin (ng/mL) | 174±207 | 155±192 | 320±251 d |
| [44; 111; 234] | [42; 93; 195] | [188; 251; 416] | |
| Iron (µg/dl) | 51.4±31.5 | 50.0±30.8 | 62.4±34.8 a |
| [30.0; 44.0; 61.0] | [30.0; 41.0; 61.0] | [42.8; 53.5; 79.0] | |
| Transferrin (mg/dL) | 202.5±44.5 | 204.4±44.0 | 188.3±46.5 |
| Transferrin saturation (%) | 18.6±11.3 | 17.8±10.7 | 24.1±13.8 b |
| [10.9; 16.0; 22.8] | [10.0; 15.0; 22.0] | [14.6; 21.7; 28.0] | |
| Hemoglobin (g/dL) | 11.17±1.72 | 11.17±1.67 | 11.12±1.99 |
| C-reactive protein (mg/dL) | 3.24±5.34 | 3.21±5.50 | 3.45±4.20 |
| [0.30; 0.98; 3.00] | [0.30; 0.89; 2.79] | [0.57; 1.52; 4.81] | |
| Creatinine (mg/dL) | 7.28±2.64 | 7.23±2.65 | 7.67±2.54 |
| [5.50; 6.80; 8.60] | [5.50; 6.70; 8.35] | [5.60; 8.20; 8.70] | |
| Albumin (g/dL) | 3.71±0.65 | 3.72±0.65 | 3.65±0.69 |
| Calcium (mg/dL) | 8.5±1.1 | 8.3±1.1 | 8.7±1.0 |
| Phosphorus (mg/dL) | 6.1±1.9 | 6.0±1.9 | 5.6±1.9 |
| iPTH (pg/mL) | 350.5±264.9 | 360.5±273.6 | 279.9±180.2 |
| [156.5; 287.2; 468.7] | [159.4; 292.7; 468.7] | [147.9; 222.9; 397.0] | |
| Bicarbonate (mEq/L) | 21.00±3.59 | 20.93±3.44 | 21.75±4.98 |
| Erythrocytes (T/L) | 3.73±0.62 | 3.75±0.62 | 3.61±0.65 |
| Leukocytes (G/L) | 8.18±3.29 | 8.27±3.26 | 7.64±3.43 |
| [6.10; 7.40; 9.90] | [6.20; 7.50; 9.95] | [5.43; 7.05; 8.83] | |
| Total cholesterol (mg/dL) | 189.8±51.0 | 189.7±50.7 | 190.3±54.7 |
| Comorbidities at baseline | |||
| CAD *, n (%) | 40 (17.0%) | 36 (17.6%) | 4 (12.9%) |
| CVD **, n (%) | 70 (29.8%) | 63 (30.9%) | 7 (22.6%) |
| PAD ***, n (%) | 40 (17.0%) | 35 (17.2%) | 5 (16.1%) |
| Follow-up | |||
| ESA, n (%) | 234 (99.6%) | 204 (100.0%) | 29 (93.5%) |
| Follow-up time (months) ‡ | 38.2±23.2 | 40.4±22.6 | 24.0±22.4 d |
| Transplantation, n (%) | 58 (24.7%) | 49 (24.0%) | 9 (29.0%) |
| All-cause mortality, n (%) | 82 (34.9%) | 66 (32.4%) | 16 (51.6%) a |
| CV mortality #, n (%) | 38 (16.2%) | 32 (15.7%) | 6 (19.4%) |
| Sepsis mortality, n (%) | 21 (8.9%) | 16 (7.8%) | 5 (16.1%) |
| CV and/or sepsis mortality, n (%) | 59 (25.1%) | 48 (23.5%) | 11 (35.5%) |
Mean ±SD [25th, 50th and 75th percentile for cases of non-normal distribution] or number (%).
p<0.05;
p<0.01;
p<0.005;
p<0.001, comparison between patients who ever received iron supplementation and patients who never received iron supplementation during the observation period.
* Coronary artery disease (CAD): myocardial infarction (MI), percutaneous transluminal coronary angioplasty (PTCA), aortocoronary bypass (ACBP).
** Cardiovascular disease (CVD): myocardial infarction (MI), percutaneous transluminal coronary angioplasty (PTCA), aortocoronary bypass (ACBP), coronary artery stenosis ≥50%, ischemic cerebral infarction, transient ischemic attack (TIA)/PRIND.
*** Peripheral arterial disease (PAD): vascular stenosis, percutaneous transluminal angioplasty (PTA), peripheral bypass, amputation.
Follow-up time was calculated as the time from the start of dialysis until the patient died or the end of the observation period was reached.
Cardiovascular mortality: myocardial infarction (MI), heart failure, sudden death, ischemic stroke, hemorrhagic stroke.