Table 1.
Demographics and clinical characteristics stratified by quartiles of FGF-23
| Variable | Full cohort N = 263 |
Quartile 1 N = 66 |
Quartile 2 N = 66 |
Quartile 3 N = 65 |
Quartile 4 N = 66 |
P value* |
|---|---|---|---|---|---|---|
| FGF-23 units (RU/mL) | 3097 (1139, 7960) | 134–1139 | 1139–3098 | 3098–7960 | 7960–15568 | NA |
| Age (y) | 63.0 (16.8) | 67.1 (17.1) | 65.8 (14.2) | 62.6 (16.5) | 56.6 (17.6) | <0.001 |
| Female | 46% | 41% | 44% | 60% | 39% | 0.7 |
| Black | 22% | 18% | 23% | 18% | 30% | 0.2 |
| Education | 0.5 | |||||
| >2-y college | 38% | 32% | 38% | 37% | 47% | |
| High school – 2 y | 52% | 58% | 56% | 51% | 44% | |
| <High school | 10% | 11% | 6% | 12% | 9% | |
| NAART Verbal IQ | 102.6 (12.3) | 100.7 (13.1) | 104.2 (11.2) | 102.4 (11.8) | 103.0 (13.2) | 0.4 |
| Diabetes | 46% | 56% | 58% | 40% | 30% | <0.001 |
| Hypertension | 90% | 86% | 97% | 86% | 89% | 0.9 |
| PVD | 22% | 29% | 21% | 14% | 24% | 0.4 |
| Stroke | 17% | 11% | 21% | 14% | 23% | 0.2 |
| CAD | 35% | 36% | 33% | 35% | 35% | 0.9 |
| CVD | 41% | 47% | 38% | 42% | 39% | 0.5 |
| Cause of ESRD | 0.08 | |||||
| Diabetes | 33% | 47% | 38% | 28% | 20% | |
| Hypertension | 19% | 17% | 15% | 26% | 18% | |
| Unknown | 29% | 16% | 29% | 26% | 45% | |
| Glomerulonephritis | 19% | 20% | 18% | 20% | 17% | |
| Calcium (mg/dL) | 9.0 (0.7) | 8.8 (0.7) | 9.0 (0.8) | 9.1 (0.7) | 9.2 (0.7) | 0.002 |
| Phosphorus (mg/dL) | 5.6(1.5) | 4.6 (1.1) | 5.3 (1.5) | 6.0 (1.1) | 6.3 (1.6) | <0.001 |
| Vitamin D 25OH (ng/mL) | 17.7 (7.7) | 18.6 (9.7) | 18.5 (7.1) | 17.0 (6.9) | 16.4 (6.7) | 0.06 |
| Hematocrit (%) | 35.3 (3.6) | 35.4 (3.0) | 35.3 (3.4) | 36.1 (3.5) | 34.5 (4.3) | 0.3 |
| Albumin (g/dL) | 3.8 (0.3) | 3.8 (0.3) | 3.7 (0.4) | 3.9 (0.3) | 3.8 (0.4) | 0.7 |
| Kt/V | 1.51 (0.24) | 1.50 (0.21) | 1.46 (0.21) | 1.60 (0.27) | 1.49 (0.25) | 0.4 |
| Dialysis vintage (mo) | 13.8 (6.4, 33.5) | 7.5 (4.1, 14.5) | 11.2 (4.9, 18.4) | 19.7 (9.7, 35.3) | 31.3 (13.0, 53.7) | <0.001 |
| DBP (mmHg) | 73.0 (12.2) | 70.6 (11.6) | 72.6 (10.4) | 74.5 (11.2) | 74.2 (14.9) | 0.06 |
| SBP (mmHg) | 141.1 (21.0) | 141.6 (16.3) | 142.7 (20.3) | 142.8 (20.1) | 137.4 (26.1) | 0.3 |
| WBC count (K/μL) | 7.4 (2.4) | 7.8 (2.7) | 7.2 (2.1) | 7.8 (2.6) | 7.0 (2.1) | 0.2 |
| CRP (mg/L) | 5.3 (2.0, 11.4) | 5.3 (2.5, 11.2) | 6.3 (2.5, 16.6) | 3.9 (1.8, 8.7) | 5.6 (1.6, 14.7) | 0.3 |
| Smoking status | 0.3 | |||||
| Current | 9% | 5% | 14% | 6% | 13% | |
| Never | 39% | 36% | 31% | 40% | 49% | |
| Past | 52% | 59% | 55% | 54% | 38% |
Presented as mean (SD), %, or median with interquartile range as appropriate.
CAD = coronary artery disease; CRP = C-reactive protein; CVD, cardiovascular disease = composite of either CAD or PVD; FGF-23 = fibroblast growth factor 23; DBP = monthly average predialysis diastolic blood pressure; NA = not applicable; NAART = North American Adult Reading Test; PVD = peripheral vascular disease; SBP = monthly average systolic blood pressure; WBC = white blood cell.
*
P value for linear trend across quartiles.