Supplemental Table 1. Baseline demographic, laboratory, and clinical characteristics of pediatric patients stratified by age.

Age Group
Variable / Total / ≤ 5 / 6-11 / 12-18 / 19 - <20
N,% / 2697 / 126(4.7) / 147(5.5) / 1120(41.5) / 1304(48.3) / P-value
Race (N,%)
White / 1024 (38.0) / 70 (55.6) / 49 (33.3) / 409 (36.5) / 496 (38.0) / <0.0001
African-American / 895 (33.2) / 22 (17.5) / 43 (29.3) / 367 (32.8) / 463 (35.5)
Hispanic / 778 (28.8) / 34 (27.0) / 55 (37.4) / 344 (30.7) / 345 (26.5)
Sex (N,%)
Male / 1490 (55.3) / 76 (60.3) / 81 (55.1) / 611 (54.6) / 722 (55.3) / 0.6738
Female / 1207 (44.8) / 50 (39.7) / 66 (44.9) / 509 (45.5) / 582 (44.6)
Primary Insurance (N,%)
Medicare / 935 (35.9) / 18 (15.7) / 36 (27.9) / 356 (33.1) / 525 (40.9) / <0.0001
Medicaid / 482 (18.5) / 38 (33.0) / 30 (23.3) / 204 (19.0) / 210 (16.3)
Other / 1188 (45.6) / 59 (51.3) / 63 (48.8) / 516 (48.0) / 550 (42.8)
Dialysis type (N,%)
Hemodialysis / 2065 (76.6) / 70 (55.6) / 90 (61.2) / 842 (75.2) / 1063 (81.5) / <0.0001
Peritoneal dialysis / 632 (23.4) / 56 (44.4) / 57 (38.8) / 278 (24.8) / 241 (18.5)
Dialysis vintage category (N,%)
Prevalent / 1005 (37.3) / 33 (26.2) / 41 (27.9) / 442 (39.5) / 489 (37.5) / 0.0023
Incident / 1692 (62.7) / 93 (73.8) / 106 (72.1) / 678 (60.5) / 815 (62.5)
Vintage (days) / 18 [4, 351] / 15[0, 89] / 6 [0,157] / 22[ 4, 404] / 18[ 5, 362] / <0.0001
Cause of ESRD (N,%)
CAKUT / 431(16.0) / 51(40.5) / 42(28.6) / 179(16.0) / 159(12.2) / <0.0001
Glomerulonephritis / 1077(39.9) / 20(15.9) / 46(31.3) / 466(41.6) / 545(41.8)
Other / 1189(44.1) / 55(43.7) / 59(40.1) / 475(42.4) / 600(46.0)
Region (N,%)
Midwest / 662 (24.6) / 40 (31.8) / 48 (32.7) / 276 (24.7) / 298 (22.9) / 0.004
Northeast / 224 (8.3) / 5 (4.0) / 5 (3.4) / 83 (7.4) / 131 (10.1)
South / 1109 (41.2) / 55 (43.7) / 53 (35.1) / 460 (41.1) / 541 (41.6)
West / 699 (26.0) / 26 (20.6) / 41 (27.9) / 300 (26.8) / 332 (25.5)
Socioeconomic Status (N,%)
High (≥$55,000) / 998 (38.0) / 54 (43.6) / 64 (47.1) / 426 (39.6) / 454 (35.1) / 0.0092
Medium / 1155 (43.9) / 58 (46.8) / 51 (37.5) / 459 (42.7) / 587 (45.4)
($35,000-<$55,000)
Low (<$35,000) / 477 (18.1) / 12 (9.7) / 21 (15.4) / 191 (17.8) / 253 (19.6)
Anthropometric measures
Height (percentile) / 21[5,58] / 3[0,29] / 13[1,49] / 19[3,49] / 29[10,61] / <0.0001
Weight (percentile) / 34[6,74] / 42[3,73] / 11[3,49] / 31[6,72] / 39[8,75] / <0.0001
BMI (percentile) / 51[13,79] / 53[8,94] / 30[5,75] / 53[15,80] / 48[13,78] / 0.0246
Laboratory measurements
Albumin (g/dL) / 3.8 ± 0.6 / 3.6 ± 0.8 / 3.8 ± 0.7 / 3.8 ± 0.6 / 3.8 ± 0.6 / 0.0002
Bicarbonate (mg/dL) / 23.0 ± 3.3 / 24.9 ± 3.4 / 22.8 ± 3.5 / 23.1 ± 3.3 / 22.8 ± 3.2 / <0.0001
Hemoglobin (g/dL) / 10.9 ± 1.7 / 11.0 ± 2.0 / 11.1 ± 1.8 / 11.0 ± 1.6 / 10.8 ± 1.6 / 0.0124
Iron (g/dL) / 64.1 ± 34.6 / 74.4 ± 43.4 / 65.0 ± 32.9 / 64.4 ± 33.4 / 62.9 ± 34.9 / 0.0129
Calcium (mg/dL) / 9.2 ± 0.9 / 10.2 ± 0.9 / 9.5 ± 0.8 / 9.2 ± 0.8 / 9.1 ± 0.8 / <0.0001
Phosphorous (mg/dL) / 5.9 ± 1.7 / 4.8 ± 1.4 / 5.6 ± 1.6 / 5.9 ± 1.6 / 6.1 ± 1.8 / <0.0001
Alkaline phosphatase (U/L) / 105[74, 173] / 375[191, 634] / 206[ 133, 291] / 113[ 82, 193] / 89[66, 127] / <0.0001
Ferritin (µg/dL) / 248[111, 496] / 204[100, 348] / 200[ 76, 477] / 232[ 100. 493] / 268[122, 513] / 0.0044
Iron Saturation (%) / 29.4 ± 14.5 / 28.4 ± 16.0 / 28.2 ± 14.0 / 29.3 ± 14.2 / 29.7 ± 14.6 / 0.581
Other measurements
Diastolic blood pressure (mmHg) / 87[58,99] / 95[90,100] / 91[61,98] / 87[59,98] / 87[57,99] / 0.1303
Systolic blood pressure (mmHg) / 99[86,100] / 100[95,100] / 99[93,100] / 98[82,100] / 99[87,100] / 0.0089
Hypertensive / 1269(62.6) / 15(79.0) / 53(70.7) / 481(59.6) / 720(63.9) / 0.0417
Median Weekly Epogen Dose / 8146 / 4000 / 4054 / 7700 / 9200 / <0.0001
[4667, 12333] / [1857, 10750] / [ 2671, 8813] / [ 4698, 11487] / [ 5500, 13200]
Single Pooled Kt/V / 1.5 ± 0.4 / 1.7 ±0.4 / 1.7 ±0.4 / 1.5 ±0.4 / 1.5 ±0.4 / 0.0004
Low spKt/V (N,%) / 620(30.4) / 4(22.2) / 17(24.3) / 290(34.8) / 309(27.7) / 0.0046
Low spKt/V HD (N,%) / 303(18.3) / 0(0) / 2(4.0) / 144(21.7) / 157(16.9) / 0.0007
Low spKt/V PD (N,%) / 317(82.6) / 4(57.1) / 15(75.0) / 146(85.4) / 152(81.7) / 0.1497
Blood Type (N,%)
A/AB / 240 (34.8) / 9 (29.0) / 19 (33.9) / 108 (34.3) / 104 (36.1) / 0.6349
B / 85 (12.3) / 1 (3.2) / 7 (12.5) / 39 (12.4) / 38 (13.2)
O / 365 (52.9) / 21 (67.7) / 30 (53.6) / 168 (53.3) / 146 (50.7)

Data presented as means ± standard deviation, median [interquartile range] and number and percentage, where appropriate. Data compared across age groups by analysis of variance or Kruskal-Wallis test for continuous variables or chi-square or Fisher’s exact test for categorical variables.

Abbreviations, BMI, body mass index; CAKUT, congenital anomalies of the kidney and urinary tract ESRD, end-stage renal disease