| Creatinine values (µmol/l) | GFR according to the CKD-Epi formula (ml/min) | Total | |||
| <15 | 15 - 29 | 30 - 59 | 60 - 89 | ||
| <15 | 0 | 0 | 1 | 3 | 4 |
| [15 - 31] | 0 | 0 | 85 | 0 | 85 |
| >31 | 18 | 22 | 231 | 0 | 271 |
| Total | 18 | 22 | 317 | 3 | 360 |