Number and proportion of reviews by Preventability scale
| Preventability score | North-East totals | Percentage of total | PRISM 2 percentage† |
| 1—Definitely not preventable | 6776 | 91.9 | 90.6 |
| 2—Slight evidence for preventability | 290 | 3.9 | 3.6 |
| 3—Possibly preventable less than 50/50 | 94 | 1.3 | 2.8 |
| 4—Probably preventable greater than 50/50 | 23 | 0.3 | 1.9 |
| 5—Strong evidence for preventability | 9 | 0.1 | 1.0 |
| 6—Definitely preventable | 2 | 0.0 | 0.0 |
| Unanswered/unable to grade | 176 | 2.4 | 0.0 |
| Total 4–6: greater than 50% chance of death being preventable | 34 | 0.5* | 3.0 |
| Total 2–6: some evidence for preventability | 418 | 5.8* | 9.4 |
↵*Percentage calculated from total patients with a score.
†Given in Table 1 of Hogan et al10