| Preventability confidence score | Adverse events n (%) | Admissions with adverse events n (%) | |||
| Causation score ⩾2 | Causation score ⩾4 | Causation score ⩾2 | Causation score ⩾2 | ||
| (1) | Virtually no evidence for preventability | 67 (49.3) | 48 (44.6) | 50 (45.4) | 36 (41.4) |
| (2) | Slight to modest evidence for preventability | 26 (19.1) | 19 (17.8) | 21 (19.0) | 14 (16.1) |
| (3) | Preventability not quite likely; less than 50–50 but close call | 13 (9.6) | 11 (10.3) | 12 (10.9) | 10 (11.5) |
| (4) | Preventability more likely than not; more than 50–50 but close call | 13 (9.6) | 12 (11.2) | 11 (10.0) | 11 (12.6) |
| (5) | Strong evidence for preventability | 11 (8.0) | 11 (10.3) | 10 (9.1) | 10 (11.5) |
| (6) | Virtually certain evidence for preventability | 6 (4.4) | 6 (5.6) | 6 (5.5) | 6 (6.9) |
| Total | 136 (100) | 107 (100) | 110 (100) | 87 (100) | |
In admissions which had more than one adverse event the preventability score is for the adverse event which had a higher preventability score.