Table 1. Participant characteristic.
| Characteristic (N = 668) | Mean (standard deviation) or number (percentage) |
| Age (year) | 70.1(6.7) |
| Male sex [n (%)] | 398(59.6) |
| Body mass index (kg/m2) | 23.6(3.7) |
| Weight (kg) | 61.9(11.7) |
| Height (cm) | 161.7(8.2) |
| Body-surface area (m2) | 1.7(0.2) |
| Serum creatinine (mg/dl) | 2.4(2.0) |
| Causes [n (%)] | |
| Diabetic nephropathy | 280(41.9) |
| Hypertension | 114(17.1) |
| Chronic tubulointerstitial disease | 45(6.7) |
| Primary glomerular disease | 68(10.2) |
| Renovascular disease | 42(6.3) |
| polycystic kidney disease | 11(1.6) |
| Other causes or causes unknown | 78(11.7) |
| Healthy volunteers | 30(4.5) |
| Measured GFR | |
| Mean (ml/min/1.73 m2) | 51.2(26.0) |
| <15 (ml/min/1.73 m2) | 60(9.0) |
| 15–29 (ml/min/1.73 m2) | 174(26.0) |
| 30–59 (ml/min/1.73 m2) | 266(39.8) |
| 60–89 (ml/min/1.73 m2) | 139(20.8) |
| >90 (ml/min/1.73 m2) | 29(4.3) |
Abbreviations: GFR, glomerular filtration rate.