Table 1.
Baseline characteristics by FGF23 and FePi above and below the median
| Variable | Low FGF23 | High FGF23 | P Value | Low FePi | High FePi | P Value |
|---|---|---|---|---|---|---|
| Number | 437 | 435 | 436 | 436 | ||
| Range (RU/ml for FGF23, % for FePi) | <42.3 | ≥42.3 | <15.7 | ≥15.7 | ||
| Age (yr)±SD | 67±11 | 67±11 | 0.77 | 65±11 | 69±11 | <0.001 |
| Sex n (%) | <0.01 | <0.001 | ||||
| Male | 374 (86) | 341 (78) | 330 (76) | 385 (88) | ||
| Female | 63 (14) | 94 (22) | 106 (24) | 51 (12) | ||
| Estrogen use (women) n (%) | 24 (38) | 17 (18) | <0.01 | 29 (27) | 12 (24) | 0.61 |
| Race n (%) | 0.04 | <0.001 | ||||
| White | 253 (58) | 278 (64) | 236 (54) | 295 (68) | ||
| Black | 63 (14) | 68 (16) | 89 (20) | 42 (10) | ||
| Other | 121 (28) | 89 (20) | 111 (25) | 99 (23) | ||
| Diabetes n (%) | 105 (24) | 122 (28) | 0.18 | 121 (28) | 106 (24) | 0.25 |
| Systolic BP (mmHg)±SD | 132±21 | 134±21 | 0.18 | 133±21 | 133±21 | 0.88 |
| BMI (kg/m2)±SD | 28.1±4.6 | 28.8±6.0 | 0.05 | 28.7±5.5 | 28.1±5.2 | 0.07 |
| Smoking n (%) | 67 (15) | 97 (22) | <0.01 | 96 (22) | 68 (16) | 0.02 |
| Total cholesterol (mg/dl)±SD | 175±39 | 180±46 | 0.07 | 179±43 | 176±42 | 0.20 |
| HDL cholesterol (mg/dl)±SD | 46±13 | 45±15 | 0.19 | 46±14 | 45±14 | 0.23 |
| CRP (mg/dl) median (IQR) | 1.8 (0.7–3.5) | 2.8 (1.1–6.3) | <0.001 | 2.3 (0.9–4.6) | 2.1 (0.9–4.8) | 0.95 |
| eGFR (ml/min per 1.73 m2)±SD | 77±19 | 65±24 | <0.001 | 77±23 | 65±20 | <0.001 |
| ACR (mg/g) median (IQR) | 8.0 (4.6–14.6) | 10.5 (5.7–23.5) | <0.001 | 8.4 (4.9–16.6) | 9.3 (5.3–20.8) | 0.22 |
| PTH (pg/ml) median (IQR) | 50 (40–65) | 56 (40–79) | <0.01 | 50 (39–65) | 56 (42–74) | <0.001 |
| Serum phosphorus (mg/dl)±SD | 3.6±0.5 | 3.8±0.6 | <0.001 | 3.8±0.5 | 3.5±0.6 | <0.001 |
| Serum calcium (mg/dl)±SD | 9.5±0.5 | 9.5±0.5 | 0.18 | 9.6±0.5 | 9.5±0.5 | 0.01 |
| Urine phosphorus (mg/dl)±SD | 47±25 | 46±25 | 0.50 | 37±21 | 56±26 | <0.001 |
| FePi (%)±SD | 16±7 | 19±10 | <0.001 | — | — | — |
| FGF23 (RU/ml) median (IQR) | — | — | — | 40 (26–60) | 47 (30–80) | <0.001 |