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Table 1 Baseline characteristics according to tertiles of ERI

From: Association between serum alkaline phosphatase and primary resistance to erythropoiesis stimulating agents in chronic kidney disease: a secondary analysis of the HERO trial

Variable ERI tertile P
Low Medium High
n 18 18 17  
ERI (IU/kg/wk/gHb) 1.4 ± 0.3 2.3 ± 0.2 3.5 ± 0.8 <0.001
ESA dose (IU/kg/wk)a 153 ± 37 233 ± 25 362 ± 79 <0.001
Type of ESA     0.8
Erythropoietin 11 (61 %) 12 (67 %) 12 (71 %)  
Darbepoetin 7 (39 %) 6 (33 %) 5 (29 %)  
Hemoglobin (g/L) 111 ± 8 102 ± 13 105 ± 10 0.05
Men 10 (56 %) 8 (44 %) 6 (35 %) 0.5
Age (years) 67.7 ± 13 58.4 ± 17.6 60.5 ± 15.5 0.2
Ethnicity     0.4
Caucasian 14 (78 %) 14 (78 %) 15 (88 %)  
Aboriginal or Torres Strait Islander 0 1 (6 %) 0  
Maori/Pacific Islander 0 1 (6 %) 0  
Asian 3 (17 %) 2 (11 %) 0  
Other 1 (6 %) 0 2 (12 %)  
Cause of kidney disease b     0.9
Diabetes 8 (44 %) 8 (47 %) 5 (29 %)  
Glomerulonephritis 2 (11 %) 1 (6 %) 4 (24 %)  
Analgesic nephropathy 0 1 (6 %) 0  
Polycystic kidney disease 1 (6 %) 1 (6 %) 1 (6 %)  
Reflux nephropathy 1 (6 %) 1 (6 %) 1 (6 %)  
Renovascular disease 0 1 (6 %) 1 (6 %)  
Others 6 (33) 4 (24 %) 5 (29 %)  
Type of dialysis b     0.4
Hemodialysis 17 (94 %) 16 (94 %) 17 (100 %)  
Peritoneal dialysis 1 (6 %) 0 0  
Pre-dialysis 0 1 (6 %) 0  
Diabetes mellitusc 10 (67 %) 9 (82 %) 6 (46 %) 0.2
Ischemic heart diseasec 7 (47 %) 4 (36 %) 7 (54 %) 0.7
Congestive heart failurec 2 (13 %) 1 (9 %) 5 (38 %) 0.1
Cerebrovascular diseasec 1 (7 %) 0 3 (23 %) 0.2
Peripheral vascular diseasec 2 (13 %) 4 (36 %) 4 (31 %) 0.4
Smoking status b     0.3
Never 9 (50 %) 5 (29 %) 9 (53 %)  
Former 8 (44 %) 11 (65 %) 5 (29 %)  
Current 1 (6 %) 1 (6 %) 3 (18 %)  
Body mass index (kg/m2) 28.6 ± 4.8 30.4 ± 7.4 29.2 ± 7.6 0.7
Body mass index category     0.3
Underweight (<18.5 kg/m2) 0 0 0  
Healthy weight (18.5 – 24.9 kg/m2) 5 (28 %) 4 (22 %) 6 (35 %)  
Overweight (25 – 29.9 kg/m2) 9 (50 %) 6 (33 %) 3 (18 %)  
Obese (>30 kg/m2) 4 (22 %) 8 (44 %) 8 (47 %)  
Hematocrit (%) 34 ± 3 32 ± 5 32 ± 3 0.7
Mean cellular volume (fL) 94.4 ± 7.8 95.3 ± 6.6 94.3 ± 5.9 0.9
Reticulocyte count (109/L) 57 ± 21 74 ± 38 64 ± 31 0.3
Total white cell count (x 109 per L) 6.8 ± 2 6.4 ± 2.1 6.6 ± 1.5 0.9
Platelet count (x 109 per L)d 207 [164, 286] 188 [167, 207] 197 [164, 274] 0.8
Ferritin (μg/L)d 413 [241, 958] 527 [298, 647] 487 [315, 594] 0.9
Transferrin saturation (%)d 26 [20, 30] 22 [17, 30] 23 [22, 29] 0.6
Serum bicarbonate (mmol/L) 23.3 ± 4 22.6 ± 3 23.6 ± 3 0.6
Albumin (g/L) 36 ± 4 35 ± 4 35 ± 5 0.7
Serum alkaline phosphatase (U/L)d 89 [64, 121] 99 [76, 134] 148 [87, 175] 0.054
Gamma-glutamyltransferase (U/L)d 23 [16, 40] 25 [17, 60] 32 [21, 57] 0.4
Alanine transaminase (U/L)d 16 [11, 19] 15 [9, 22] 10 [8, 19] 0.2
Aspartate transaminase (U/L)d 18 [13, 22] 17 [12, 23] 14 [10, 17] 0.3
Lactate dehydrogenase (U/L) 224 ± 57 224 ± 85 265 ± 63 0.2
Albumin-corrected calcium (mmol/L) 2.3 ± 0.2 2.3 ± 0.1 2.2 ± 0.2 0.2
Phosphate (mmol/L)e 1.7 ± 0.5 1.7 ± 0.5 1.7 ± 0.5 0.9
Parathyroid hormone (pmol/L)d,f 17 [9, 35] 33 [17, 42] 32 [16, 65] 0.2
C-reactive protein (mg/L) 3 [2, 21] 12 [4, 28] 15 [7, 31] 0.06
Oxidative stress substudy     
n 14 13 14  
Total F2-isoprostanes (pg/mL)d 133 [87, 213] 143 [128, 200] 112 [67, 173] 0.3
Glutathione peroxidise activity (U/L) 177 (13) 181 (10) 174 (14) 0.4
Superoxide dismutase activity (U/mL)d,f 1.97 [1.41, 2.6] 2.01 [1.32, 2.44] 2.22 [1.71, 2.71] 0.7
Protein carbonyls (nmol/mg)d 0.56 [0.46, 0.6] 0.55 [0.46, 0.74] 0.55 [0.51, 0.69] 0.9
  1. aPatients on darbepoetin were converted to an erythropoietin-equivalent dose using a conversion factor of 200:1
  2. b1 missing data from medium ERI tertile
  3. cMissing data- 3, 7 and 4 values missing from low, medium and high ERI tertiles, respectively
  4. dMedian [IQR]
  5. eto convert phosphate level from mmol/L to mg/dL multiply by 3.1
  6. fto convert parathyroid level from pmol/L to pg/mL multiply by 9.4