Perioperative characteristics of 2180 participating patients
| Variables | Total (n=2180) | No moderate-severe pain within 24 hours (n=1997) | Moderate-severe pain within 24 hours (n=183) | P values |
| Types of surgery, n (%) | 0.013 | |||
| Hepatic resection | 897 (41.1) | 819 (41) | 78 (42.6) | |
| Pancreatoduodenectomy | 184 (8.4) | 157 (7.9) | 27 (14.8) | |
| Splenectomy and pancreatectomy | 238 (10.9) | 225 (11.3) | 13 (7.1) | |
| Surgery for bile duct cancer and gall bladder cancer | 187 (8.6) | 169 (8.5) | 18 (9.8) | |
| Choledocholithiasis | 577 (26.5) | 536 (26.8) | 41 (22.4) | |
| Other surgery | 97 (4.4) | 91 (4.6) | 6 (3.3) | |
| Laparoscopic surgery, n (%) | < 0.001 | |||
| No | 1436 (65.9) | 1280 (64.1) | 156 (85.2) | |
| Yes | 744 (34.1) | 717 (35.9) | 27 (14.8) | |
| Postoperative analgesia protocol, n (%) | < 0.001 | |||
| Butorphanol | 1539 (70.6) | 1468 (73.5) | 71 (38.8) | |
| Sufentanil | 641 (29.4) | 529 (26.5) | 112 (61.2) | |
| Preoperative Hb (g/dL) | 126.1±21.2 | 126.0±21.4 | 127.9±19.4 | 0.238 |
| Perioperative blood transfusion, n (%) | 0.382 | |||
| No | 1720 (78.9) | 1571 (78.7) | 149 (81.4) | |
| Yes | 460 (21.1) | 426 (21.3) | 34 (18.6) | |
| Anaesthesia duration (min) | 249.7±106.7 | 248.5±106.9 | 262.1±103.6 | 0.099 |
| Surgery duration (min) | 235.2±105.7 | 234.0±105.9 | 248.0±103.0 | 0.085 |
| Anaesthetic methods, n (%) | 0.144 | |||
| General anaesthesia | 237 (10.9) | 223 (11.2) | 14 (7.7) | |
| General anaesthesia with nerve block | 1943 (89.1) | 1774 (88.8) | 169 (92.3) | |
| Nerve block, n (%) | 0.395 | |||
| No | 237 (10.9) | 223 (11.2) | 14 (7.7) | |
| Thoracic nerve block | 1344 (61.7) | 1217 (60.9) | 127 (69.4) | |
| Quadratus lumborum block | 281 (12.9) | 261 (13.1) | 20 (10.9) | |
| TAP | 194 (8.9) | 181 (9.1) | 13 (7.1) | |
| Rectus sheath block | 90 (4.1) | 84 (4.2) | 6 (3.3) | |
| Others | 34 (1.6) | 31 (1.6) | 3 (1.6) | |
| Preoperative days (d) | 5.5±3.8 | 5.5±3.9 | 5.2±3.2 | 0.232 |
| Postoperative days (d) | 11.5±5.7 | 11.4±5.7 | 12.7±6.0 | 0.004 |
| VAS at rest | 1.0 (0.0, 2.0) | 0.0 (0.0, 1.0) | 5.0 (4.0, 6.0) | < 0.001 |
| VAS at movement | 2.0 (1.0, 3.0) | 2.0 (1.0, 3.0) | 6.0 (5.0, 7.0) | < 0.001 |
| Postoperative nausea, n (%) | 50 (2.3) | 41 (2.1) | 9 (4.9) | 0.033 |
| Postoperative vomiting, n (%) | 29 (1.3) | 23 (1.2) | 6 (3.3) | 0.03 |
TAP, Transversus Abdominis Plane Block; VAS, Visual Analogue Scale.