| Reference | Brennan et al25 | Wilson et al3 | Thomas et al2 | Vincent et al26 | Davis et al24 | Baker et al31 | Median percentage (interquartile range) |
| No. of adverse events/total no. of records | 1133/30 121 | 2952/14 179 | 475/14 700 | 118/1 014 | 1060/6 579 | 360/3 745 | – |
| Operation-related | 599 (52.9) | 1159 (49.3) | 213 (44.9) | 40 (33.9) | 258 (24.3) | 123 (34.2) | 39.6 (31.5 to 50.2) |
| Drug-related | 178 (15.7) | 249 (10.6) | 92 (19.3) | 17 (14.4) | 130 (12.3) | 85 (23.6) | 15.1 (11.9 to 20.4) |
| Diagnostic | 79 (7.0) | 314 (13.3) | 33 (6.9) | 5 (4.2) | 85 (8.0) | 38 (10.6) | 7.5 (6.2 to 11.3) |
| Therapeutic | 62 (5.5) | 276 (11.7) | 21 (4.4) | – | 89 (8.4) | – | 7.0 (4.7 to 10.9) |
| Procedure* | 88 (7.8) | 197 (8.4) | 64 (13.5) | 6 (5.1) | 82 (7.7) | 26 (7.2) | 7.8 (6.7 to 9.7) |
| Fall/fracture | 38 (3.4) | 192 (8.2) | 8 (1.7) | – | – | 8 (2.2) | 2.8 (1.8 to 7.0) |
| Postpartum/obstetric | 18 (1.6) | 126 (5.4) | 17 (3.6) | – | – | 1 (0.3) | 2.6 (0.6 to 5.0) |
| Anaesthesia-related | 13 (1.1) | 51 (2.2) | 6 (1.3) | 6 (5.1) | – | 7 (2.0) | 2.0 (1.2 to 3.7) |
| Neonatal | 29 (3.0) | 30 (1.3) | 15 (3.1) | – | – | – | 3.0 (1.3 to 3.1) |
| System†/other | 29 (3.0) | 358 (15.2) | 7 (1.5) | – | 416 (39.3) | 29 (8.1) | 8.1 (2.3 to 27.3) |
| Ward management | – | – | – | 30 (25.4) | – | – | – |
| Discharge | – | – | – | 14 (11.9) | – | – | – |
| Other clinical management | – | – | – | – | – | 43 (11.9) | – |
Brennan: numbers were given, percentages were calculated. Wilson: numbers and percentages were given. Thomas: percentages were given, and numbers were calculated. Vincent: numbers were given, and percentages were calculated. Davis: numbers and percentages were given. Baker: numbers were given, and percentages were calculated. Numbers (percentages) except last column. Interquartile range = 25th to 75th percentile.
*Medical procedure such as coronary angiography or endoscopy.
†Contains: defective equipment or supplies, inadequate reporting or communication, inadequate staffing, training or supervision, no protocol/failure to implement protocol.