| Reference | Brennan et al25 | Wilson et al3 | Thomas et al2 | Davis et al24 | Median percentage (interquartile range) |
| No. of adverse events/total no. of records | 1133/30 121 | 2353/14 179 | 475/14 700 | 850/6579 | – |
| In hospital | 920 (81.2) | 1741 (74.0) | 398 (83.8) | 683 (80.4) | 80.8 (75.6 to 83.2) |
| Operating room | 465 (41.0) | 1077 (45.8) | 188 (39.5) | – | 41.0 (39.5 to 45.8) |
| Patient’s room | 300 (26.5) | 577 (24.5) | 103 (21.6) | – | 24.5 (21.6 to 26.5) |
| Emergency room | 33 (2.9) | – | 14 (3.0) | – | 3.0 (2.9 to 3.0) |
| Labour and delivery room | 32 (2.8) | 87 (3.7) | 31 (6.5) | – | 3.7 (2.8 to 6.5) |
| Intensive care unit | 31 (2.7) | – | 17 (3.5) | – | 3.1 (2.7 to 3.5) |
| Radiology | 23 (2.0) | – | – | – | – |
| Cardiac catheterisation laboratory | 10 (0.9) | – | 20 (4.2) | – | 2.6 (0.9 to 4.2) |
| Ambulatory care unit | 9 (0.8) | – | – | – | – |
| Procedure room | – | – | 16 (3.4) | – | – |
| Other | 19 (1.7) | – | 10 (2.2) | – | 2.0 (1.7 to 2.2) |
| Out of hospital | 156 (13.8) | 297 (12.6) | 76 (16.0) | 167 (19.6) | 14.9 (12.9 to 18.7) |
| Physician’s office | 87 (7.7) | 200 (8.5) | 33 (7.0) | 54 (6.4) | 7.4 (6.6 to 8.3) |
| Patient’s home | 31 (2.7) | 56 (2.4) | 16 (3.4) | 45 (5.3) | 3.1 (2.5 to 4.8) |
| Ambulatory care unit | 16 (1.4) | – | – | 11 (1.3) | 1.4 (1.3 to 1.4) |
| Nursing home | 10 (0.9) | 41 (1.7) | 3 (0.6) | 32 (3.8) | 1.3 (0.7 to 3.3) |
| Day surgery | – | – | 6 (1.2) | – | – |
| Private hospital | – | – | – | 17 (2.0) | – |
| Other | 12 (1.1) | – | 18 (3.8) | 8 (0.9) | 1.1 (0.9 to 3.8) |
| Unknown | 58 (5.1) | 315 (13.4) | 1 (0.3) | – | 5.1 (0.3 to 13.4) |
Numbers (percentages) except last column. Interquartile range = 25th to 75th percentile. Brennan: percentages were given, and numbers were calculated. Wilson: numbers and percentages were given. Thomas: percentages were given, and numbers were calculated. Davis: percentages were given, and numbers were calculated.