Table 1.

Baseline characteristics of participants according to fibroblast growth factor 23 quartiles

VariableFGF23 Quartile 1: <95.8 RU/ml (n=969)FGF23 Quartile 2: 95.8–145.4 RU/ml (n=970)FGF23 Quartile 3: 145.5–239.1 RU/ml (n=970)FGF23 Quartile 4: ≥239.2 RU/ml (n=970)
Sociodemographic and clinical characteristics
 age (yr)56.6±11.358.7±10.959±10.858.3±10.9
 women, n (%)349 (36.0)385 (39.7)455 (46.9)548 (56.5)
 blacks, n (%)404 (41.7)374 (38.6)386 (39.8)456 (47)
 Hispanics, n (%)72 (7.4)138 (14.2)138 (14.2)148 (15.3)
 hypertension, n (%)731 (75.4)843 (87)872 (89.9)893 (92.1)
 diabetes, n (%)291 (30)443 (45.7)552 (56.9)593 (61.1)
 current smoking, n (%)76 (7.8)97 (10)132 (13.6)203 (20.9)
 body mass index (kg/m)30.6±6.731.5±732.4±7.933.9±9.1
 statin use, n (%)432 (45)537 (55.9)592 (61.5)566 (58.5)
Laboratory results
 creatinine (mg/dl)1.5±0.41.7±0.51.9±0.62.2±0.8
 eGFR (ml/min per 1.73 m2)52.1±12.145.5±11.739.2±10.934.3±12.2
 albumin (g/dl)4.0±0.44±0.43.9±0.53.8±0.5
 calcium (mg/dl)9.2±0.49.2±0.59.2±0.59.1±0.6
 phosphate (mg/dl)3.4±0.53.6±0.63.8±0.64.1±0.8
 parathyroid hormone (pg/ml)40 (29–59)47.4 (32–73)62.8 (40–105)82.5 (47–137)
 25-hydroxyvitamin D (ng/ml)a28.9 (18.9–39.4)27.7 (17.6–37.8)25.2 (15.7–36.7)21.3 (12.4–31.4)
 1,25-dihydroxyvitamin D (ng/ml)a30.8 (22.3–43.0)28.6 (20.2–38.1)23.5 (16.2–33.5)20.0 (13.3–28.0)
 urine albumin/creatinine ratio (mg/g)14.5 (5–121.7)32 (6.5–272)103.9(15–716)214.1 (28–1310)
 fractional excretion of phosphate (%)22.3 (17.2–28.9)24.1 (17.8–32.1)26.5 (20.2–36.7)30.5 (21.7–41.6)
Inflammatory markers
 IL-6 (pg/mL)1.3 (0.8–2.1)1.7 (1.0–2.7)2.0 (1.3–3.1)2.9 (1.8–4.8)
 high-sensitivity C-reactive protein (mg/L)1.9 (0.9–4.6)2.2 (1.0–4.9)2.6 (1.1–6.7)4.1 (1.5–8.6)
 TNF-α (pg/mL)1.7 (1.1–2.5)2.0 (1.4–2.9)2.4 (1.7–3.4)2.9 (2.1–3.9)
 fibrinogen (g/L)3.7±0.93.9±1.04.3±1.24.7±1.4
  • Values expressed with a plus/minus sign are the mean ± SD. Numbers with ranges in parentheses are medians and interquartile ranges. FGF23, fibroblast growth factor 23; eGFR, estimated GFR.

  • a Levels of 25-dihydroxyvitamin D and 1,25-dihydroxyvitamin D were available in 1502 and 1527 participants, respectively, at the year 1 follow-up visit