Table 2.

Baseline characteristics of study participants by quartiles of baseline serum FGF23 levels

FGF23 Levels (pg/ml)Q1Q2Q3Q4P Value for Trend
<724728–31153122–12923>12932
n=335n=335n=335n=335
Age; years61 (13)60 (13)58(14)51 (15)<0.001
Female; N221 (66.0)183 (54.6)175 (52.2)159 (47.5)<0.001
Black; N243 (72.5)214 (63.9)213 (63.6)188 (56.1)<0.001
Dialysis duration; years2.1 [1.0–3.9]2.5 [1.4–4.5]2.6 [1.5–5.3]3.6 [2.0–6.6]<0.001
Diabetes; N180 (53.7)166 (49.6)146 (43.6)95 (28.4)<0.001
CVD; N265 (79.1)280 (83.6)268 (80.0)243 (72.5)0.005
Catheter use; N22 (6.6)19 (5.7)21 (6.3)10 (3.0)0.15
Current smoking; N160 (47.8)178 (53.1)163 (48.8)175 (52.2)0.44
High-Kt/V assignment; N173 (51.6)171 (51.0)172 (51.3)153 (45.7)0.35
High-Flux assignment; N167 (49.8)190 (56.7)158(47.2)159 (47.5)0.05
Serum albumin; mg/dl3.5 (0.4)3.6 (0.3)3.6 (0.3)3.7 (0.4)<0.001
Serum calcium; mg/dl9.1 (0.8)9.1 (0.9)9.4 (0.9)9.6 (1.1)<0.001
Serum phosphorus; mg/dl4.4 (1.3)5.6 (1.5)6.0 (1.7)7.1 (1.9)<0.001
Serum 25(OH)D; ng/ml18 [13–24]19 [14–25]19 [14–28]21 [15–31]0.001
Serum 1,25(OH)2D; pg/ml5.7 [3.0–13.1]5.3 [2.4–12.4]6.8 [2.8–15.0]8.0 [3.2–16.6]0.01
Serum iPTH; pg/ml171 [73–327]188 [87–396]159 [75–411]284 [101–552]<0.001
Serum hs-CRP; mg/L6.4 [2.4–17.0]6.5[3.1–14.9]6.2 [2.8–12.8]5.1[2.2–13.9]0.48
Serum IL-6; pg/ml2.8 [1.6–6.6]3.5 [1.7–7.9]2.9 [1.7–7.4]3.1 [1.6–5.7]0.25
Serum TNF-α; pg/ml29.8 [18.1–42.7]31.4 [20.1–46.7]30.0 [20.6–42.2]29.0 [19.6–42.8]0.66
Serum IFN-δ; pg/ml1.3 [1.1–1.8]1.5 [1.1–2.1]1.4 [1.1–2.1]1.5 [1.1–2.1]0.004
Vitamin D analog administration; %159 (47.5)166 (49.6)185 (55.2)210 (62.7)<0.001
  • Data are presented as N (%), mean (SD) or median [IQR].