Distribution of different types of primary incidents
| Types of primary incident: incidents occurring proximal (chronologically) to the patient outcome | At least slight to modest evidence of avoidability, n (%) | At least possible evidence of avoidability, n (%) | At least probable evidence of avoidability, n (%) |
| Diagnostic errors | 45 (60.8) | 34 (61.8) | 22 (64.7) |
| Wrong diagnosis—original diagnosis is found to be incorrect because the true cause is discovered later. | 16 (21.6) | 13 (23.6) | 11 (32.4) |
| Delayed diagnosis (non-cancer)—diagnosis could have been made earlier if care was evidence-based. | 21 (28.4) | 15 (27.3) | 10 (29.4) |
| Delayed cancer diagnosis | 8 (10.8) | 6 (10.9) | 1 (2.9) |
| Medication errors | 19 (25.7) | 13 (23.6) | 6 (17.6) |
| No drug treatment given | 4 (5.4) | 3 (5.4) | 2 (5.9) |
| Insufficient drug treatment given | 4 (5.4) | 4 (7.3) | 1 (2.9) |
| Prescribing errors | 6 (8.1) | 4 (7.3) | 1 (2.9) |
| Monitoring errors | 2 (2.7) | 2 (3.6) | 2 (5.9) |
| Adverse drug reaction | 1 (1.3) | – | – |
| Medication not commenced in a timely manner | 1 (1.3) | – | – |
| Vaccine administration | 1 (1.3) | – | – |
| Referral errors | 8 (10.8) | 7 (12.7) | 6 (17.6) |
| Delayed referral | 7 (9.4) | 6 (10.9) | 6 (17.6) |
| Referral not performed when indicated | 1 (1.3) | 1 (1.8) | – |
| Other | 2 (2.7) | 1 (1.8) | – |
| Patient communication not sent from secondary to primary care | 1 (1.3) | 1 (1.8) | – |
| Incorrect test ordered | 1 (1.3) | – | – |
| Total (%) | 74 (100) | 55 (100) | 34 (100) |