| Score given | 1 | 2 | 3 |
| Age | <50 | ⩾50 | – |
| WCC (109/l) | <15 | ⩾15 | – |
| Urea (mmol/l) | <5 | ⩾5 | – |
| PT ratio or INR | <1.5 | 1.5–2.0 | >2.0 |
| Bilirubin (μmol/l) | <125 | 125–250 | >250 |
INR, International normalised ratio; PT, prothrombin time; WCC, white cell count. Each variable is given a score and then a combined score of between 5 and 12 is obtained. A score greater than or equal to 9 is associated with a poor prognosis.2