Table 1.
Baseline characteristics of patients according to FGF23 quartile.
| Variables | FGF23 quartiles | Total | p-value | |||
|---|---|---|---|---|---|---|
| Quartile 1 (0.0–1.7) | Quartile 2 (1.8–19.6) | Quartile 3 (19.7–34.6) | Quartile 4 (34.7–774.0) | |||
| Number | 522 | 522 | 523 | 522 | 2,089 | |
| Age (years) | 52.6 ± 12.4 | 53.0 ± 12.2 | 54.6 ± 11.9 | 54.0 ± 12.4 | 53.6 ± 12.2 | 0.04 |
| Sex (Male, %) | 321 (61.5) | 318 (60.9) | 345 (66.0) | 291 (55.7) | 1,275 (61.0) | 0.01 |
| Smoking (n, %) | 238 (45.6) | 232 (44.8) | 262 (50.1) | 240 (46.0) | 972 (46.5) | 0.41 |
| DM (n, %) | 140 (26.8) | 145 (27.8) | 189 (36.1) | 236 (45.2) | 710 (34.0) | <0.001 |
| HTN (n, %) | 491 (94.1) | 503 (96.4) | 508 (97.1) | 506 (96.9) | 2,008 (96.9) | 0.41 |
| BMI (kg/m2) | 24.5 ± 3.2 | 24.6 ± 3.4 | 24.7 ± 3.5 | 24.4 ± 3.5 | 24.5 ± 3.4 | 0.65 |
| SBP (mmHg) | 127.9 ± 15.7 | 126.6 ± 14.7 | 127.7 ± 16.5 | 132.0 ± 18.3 | 128.5 ± 16.5 | <0.001 |
| DBP (mmHg) | 77.1 ± 11.3 | 76.2 ± 10.8 | 76.1 ± 10.9 | 78.0 ± 11.6 | 94.1 ± 11.7 | 0.02 |
| MAP (mmHg) | 94.0 ± 11.5 | 93.0 ± 11.0 | 93.3 ± 11.5 | 96.0 ± 12.6 | 76.9 ± 11.2 | <0.001 |
| Anemia (n, %) | 165 (31.6) | 178 (34.1) | 253 (48.4) | 329 (63.0) | 925 (44.3) | <0.001 |
| Charlson comorbidity index | 1.9 ± 1.6 | 2.1 ± 1.6 | 2.5 ± 1.5 | 2.8 ± 1.6 | 2.3 ± 1.6 | <0.001 |
| Creatinine (mg/dl) | 1.5 ± 0.8 | 1.5 ± 0.8 | 1.9 ± 1.1 | 2.3 ± 1.5 | 1.8 ± 1.1 | <0.001 |
| eGFR (ml/min/1.73 m2) | 59.1 ± 30.1 | 56.8 ± 31.2 | 45.6 ± 26.7 | 39.8 ± 28.5 | 50.3 ± 30.2 | <0.001 |
| CKD stage | ||||||
| 1 (n, %) | 116 (22.2) | 106 (20.3) | 61 (11.7) | 53 (10.2) | 336 (16.1) | <0.001 |
| 2 (n, %) | 137 (26.2) | 105 (20.1) | 86 (16.4) | 64 (12.3) | 392 (18.8) | <0.001 |
| 3 (n, %) | 183 (35.1) | 218 (41.8) | 211 (40.3) | 170 (32.6) | 782 (37.4) | 0.006 |
| 4 (n, %) | 72 (13.8) | 82 (15.7) | 133 (25.4) | 162 (31.0) | 439 (21.0) | <0.001 |
| 5 (n, %) | 14 (2.7) | 11 (2.1) | 32 (6.1) | 73 (14.0) | 130 (6.2) | <0.001 |
| WBC (x103/mm3) | 6.5 ± 2.0 | 6.6 ± 1.8 | 6.7 ± 1.9 | 6.6 ± 2.0 | 6.6 ± 1.9 | 0.26 |
| Hemoglobin (g/dl) | 13.3 ± 1.8 | 13.2 ± 1.9 | 12.8 ± 2.1 | 12.0 ± 2.0 | 12.8 ± 2.0 | <0.001 |
| Platelet (x103/mm3) | 228.8 ± 62.2 | 231.0 ± 58.0 | 231.9 ± 59.8 | 232.2 ± 65.7 | 231.0 ± 61.5 | 0.81 |
| Iron (µg/dl) | 95.5 ± 35.0 | 98.1 ± 36.6 | 93.6 ± 34.6 | 83.2 ± 32.8 | 92.6 ± 35.2 | <0.001 |
| Ferritin (ng/ml)* | 101.5 (58.6–176.0) |
91.0 (52.2–161.9) |
100.3 (53.6–186.3) |
101.0 (49.4–175.2) |
98.3 (53.3–175.7) |
0.45 |
| Transferrin saturation (%) | 32.2 ± 11.7 | 33.1 ± 12.7 | 31.8 ± 11.8 | 29.4 ± 11.9 | 31.7 ± 12.1 | <0.001 |
| Hepcidin (ng/ml)* | 11.5 (5.8–22.8) |
11.7 (6.1–21.5) |
14.4 (7.2–25.8) |
16.5 (7.8–30.4) |
13.4 (6.6–25.1) |
<0.001 |
| Total cholesterol (mg/dl) | 176.5 ± 38.3 | 175.4 ± 37.3 | 172.8 ± 39.7 | 173.1 ± 42.2 | 174.4 ± 39.4 | 0.37 |
| Albumin (g/dl) | 4.2 ± 0.4 | 4.2 ± 0.4 | 4.2 ± 0.4 | 4.1 ± 0.5 | 4.2 ± 0.4 | <0.001 |
| Calcium (mg/dl) | 9.2 ± 0.5 | 9.2 ± 0.5 | 9.1 ± 0.5 | 9.0 ± 0.6 | 9.1 ± 0.5 | <0.001 |
| Phosphate (mg/dl) | 3.6 ± 0.6 | 3.6 ± 0.6 | 3.7 ± 0.6 | 4.0 ± 0.8 | 3.7 ± 0.7 | <0.001 |
| iPTH (pg/ml)* | 44.5 (29.0–68.9) |
46.1 (31.2–70.3) |
53.0 (35.0–86.3) |
69.0 (41.6–121.8) |
51.6 (33.2–84.7) |
<0.001 |
| 1,25(OH)2 vitamin D (pg/ml) | 32.1 ± 17.2 | 29.2 ± 13.3 | 27.4 ± 12.7 | 25.7 ± 5.3 | 28.6 ± 14.4 | <0.001 |
| FGF23 (RU/ml)* | 0.03 (0.0–0.4) |
9.5 (4.8–15.9) |
25.5 (22.3–29.8) |
52.9 (41.3–75.3) |
19.6 (1.7–34.6) |
<0.001 |
| CRP (mg/dl)* | 0.7 (0.2–1.6) | 0.6 (0.2–1.4) | 0.6 (0.3–1.6) | 0.7 (0.2–2.2) | 0.6 (0.2–1.6) | 0.04 |
| Proteinuria (g/24 h)* | 0.4 (0.1–1.1) | 0.5 (0.2–1.2) | 0.7 (0.2–1.9) | 0.7 (0.3–2.2) | 0.5 (0.2–1.6) | <0.001 |
| Treatment | ||||||
| RAS blockers (n, %) | 446 (85.4) | 452 (86.6) | 436 (83.4) | 448 (85.8) | 1,782 (85.3) | 0.50 |
| Statin (n, %) | 262 (50.2) | 273 (52.3) | 277 (53.0) | 267 (51.1) | 1,079 (51.8) | 0.84 |
| Iron replacement (n, %) | 50 (9.6) | 62 (11.9) | 82 (15.7) | 113 (21.6) | 179 (8.6) | <0.001 |
| ESA therapy (n, %) | 19 (3.6) | 27 (5.2) | 35 (6.7) | 78 (14.9) | 167 (7.5) | <0.001 |
All data are expressed as mean ± SD or *median (and interquartile range)
Abbreviations: FGF23, fibroblast growth factor 23; DM, diabetes mellitus; HTN, hypertension; BMI, body mass index; SBP, systolic blood pressure; DBP, diastolic blood pressure; MAP, mean arterial pressure; eGFR, estimated glomerular filtration rate; CKD, chronic kidney disease; WBC, white blood cell; iPTH, intact parathyroid hormone; S-Klotho, soluble α-Klotho; CRP, C-reactive protein; RAS, renin-angiotensin system; ESA, erythropoiesis-stimulating agent.