Table 1.

Baseline characteristics of study participants by quartiles of baseline serum 25(OH)D levels

25 (OH)D Levels (ng/ml)Q1Q2Q3Q4P Value For Trend
<1414–1919–26>26
n=335n=335n=335n=335
Age; years58 (13)59 (13)58 (14)55 (16)0.01
Female; N243 (72.5)204 (60.7)170 (50.9)121 (36.1)<0.001
Black; N252 (75.2)234 (69.6)214 (64.1)158 (47.2)<0.001
Dialysis duration; years2.6 [1.4–4.7]2.5 [1.5–4.8]2.6 [1.3–5.0]3.0 [1.4–5.7]0.56
Diabetes; N184 (54.9)168 (50.0)132 (39.5)103 (30.8)<0.001
CVD; N276 (82.4)271 (80.6)260 (77.8)249 (74.3)0.06
Catheter use; N23 (6.9)21 (6.2)13 (3.9)15 (4.5)0.27
Current smoking; N155 (46.3)158 (47.2)180 (53.9)183 (54.6)0.05
High-Kt/V assignment; N160 (47.8)175 (52.1)161(48.2)173(51.6)0.56
High-flux assignment; N175(52.2)167(49.7)169(50.6)163(48.7)0.82
Serum albumin; mg/dl3.5 (0.4)3.6 (0.4)3.6 (0.3)3.7 (0.3)<0.001
Serum calcium; mg/dl9.2 (0.9)9.3 (0.9)9.3 (0.9)9.5 (1.0)<0.001
Serum phosphorus; mg/dl5.7 (2.0)5.8 (1.8)5.8 (1.8)5.8 (2.0)0.92
Serum 1,25(OH)2D; pg/ml3.3 [1.6–10.8]5.2 [2.3–14.2]6.0 [3.4–14.7]8.9 [5.4–17.8]<0.001
Serum iPTH; pg/ml249 [113–456]185 [75–411]185 [86–398]165 [66–418]0.001
Serum FGF23; pg/ml2403 [582–9755]3357 [846–12247]2365 [609–11905]4458 [1039–19010]<0.001
Serum hs-CRP; mg/L7.8 [2.9–16.6]6.3 [2.9–15.8]6.0 [2.6–14.2]4.8 [2.2–12.4]0.01
Serum IL-6; pg/ml3.3 [1.7–8.3]3.1 [1.7–6.6]3.2 [1.8–6.8]2.7 [1.5–5.7]0.07
Serum TNF-α; pg/ml30.2 [19.4–46.7]27.4 [18.8–40.0]32.1 [21.8–44.8]30.1 [19.7–46.1]0.09
Serum IFN-γ; pg/ml1.4 [1.1–2.0]1.4 [1.1–1.9]1.5 [1.2–2.1]1.4 [1.1–2.2]0.29
Vitamin D analog administration; %179 (53.4)194 (57.7)178 (53.3)169 (50.4)0.30
  • Data are presented as N (%), mean (SD) or median [IQR].