Table 2.

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

FGF23 Levels (pg/ml)	Q1	Q2	Q3	Q4	P Value for Trend
	<724	728–3115	3122–12923	>12932
	n=335	n=335	n=335	n=335
Age; years	61 (13)	60 (13)	58(14)	51 (15)	<0.001
Female; N	221 (66.0)	183 (54.6)	175 (52.2)	159 (47.5)	<0.001
Black; N	243 (72.5)	214 (63.9)	213 (63.6)	188 (56.1)	<0.001
Dialysis duration; years	2.1 [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; N	180 (53.7)	166 (49.6)	146 (43.6)	95 (28.4)	<0.001
CVD; N	265 (79.1)	280 (83.6)	268 (80.0)	243 (72.5)	0.005
Catheter use; N	22 (6.6)	19 (5.7)	21 (6.3)	10 (3.0)	0.15
Current smoking; N	160 (47.8)	178 (53.1)	163 (48.8)	175 (52.2)	0.44
High-Kt/V assignment; N	173 (51.6)	171 (51.0)	172 (51.3)	153 (45.7)	0.35
High-Flux assignment; N	167 (49.8)	190 (56.7)	158(47.2)	159 (47.5)	0.05
Serum albumin; mg/dl	3.5 (0.4)	3.6 (0.3)	3.6 (0.3)	3.7 (0.4)	<0.001
Serum calcium; mg/dl	9.1 (0.8)	9.1 (0.9)	9.4 (0.9)	9.6 (1.1)	<0.001
Serum phosphorus; mg/dl	4.4 (1.3)	5.6 (1.5)	6.0 (1.7)	7.1 (1.9)	<0.001
Serum 25(OH)D; ng/ml	18 [13–24]	19 [14–25]	19 [14–28]	21 [15–31]	0.001
Serum 1,25(OH)2D; pg/ml	5.7 [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/ml	171 [73–327]	188 [87–396]	159 [75–411]	284 [101–552]	<0.001
Serum hs-CRP; mg/L	6.4 [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/ml	2.8 [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/ml	29.8 [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/ml	1.3 [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].