TABLE 1.
Characteristics according to tertiles of hospital‐ and surgeon‐level mean annual volumes.
| Hospital‐level volume | Surgeon‐level volume | |||||||
|---|---|---|---|---|---|---|---|---|
| Low volume (<22; 60 hospitals), n (%) (N = 2701) | Mid volume (22–31; 51 hospitals), n (%) (N = 4066) | High volume (32–74; 55 hospitals), n (%) (N = 7091) | p‐value | Low volume (1–3; 268 surgeons), n (%) (N = 1414) | Mid volume (4–6; 322 surgeons), n (%) (N = 4747) | High volume (>6, 256 surgeons), n (%) (N = 7680) | p‐value | |
| Age (years) | ||||||||
| <50 | 225 (8.3) | 273 (6.7) | 515 (7.3) | 0.021* | 98 (6.9) | 354 (7.5) | 558 (7.3) | 0.265 |
| 50–59 | 512 (19.0) | 726 (17.9) | 1265 (17.8) | 237 (16.8) | 831 (17.5) | 1432 (18.6) | ||
| 60–74 | 1259 (46.6) | 2091 (51.4) | 3528 (49.8) | 740 (52.3) | 2380 (50.1) | 3753 (48.9) | ||
| 75–84 | 622 (23.0) | 857 (21.1) | 1574 (22.2) | 291 (20.6) | 1048 (22.1) | 1710 (22.3) | ||
| ≥85 | 83 (3.1) | 119 (2.9) | 209 (2.9) | 48 (3.4) | 134 (2.8) | 227 (3.0) | ||
| Sex | ||||||||
| Male | 1787 (66.2) | 2639 (64.9) | 4599 (64.9) | 0.452 | 948 (67.0) | 3041 (64.1) | 5026 (65.4) | 0.082 |
| Female | 914 (33.8) | 1427 (35.1) | 2492 (35.1) | 466 (33.0) | 1706 (35.9) | 2654 (34.6) | ||
| Ethnicity | ||||||||
| White | 2383 (92.1) | 3709 (95.8) | 6418 (95.8) | <0.001* | 1253 (92.2) | 4328 (95.3) | 6913 (95.5) | <0.001* |
| Other | 205 (7.9) | 161 (4.2) | 280 (4.2) | 106 (7.8) | 214 (4.7) | 326 (4.5) | ||
| Missing | 113 (4.2) | 196 (4.8) | 393 (5.5) | 55 (3.9) | 205 (4.3) | 441 (5.7) | ||
| IMDQ | ||||||||
| 1 (most deprived) | 411 (15.2) | 697 (17.2) | 977 (13.8) | <0.001* | 241 (17.1) | 771 (16.3) | 1069 (13.9) | <0.001* |
| 2 | 543 (20.1) | 725 (17.9) | 1164 (16.4) | 262 (18.5) | 861 (18.2) | 1304 (17.0) | ||
| 3 | 603 (22.4) | 856 (21.1) | 1501 (21.2) | 298 (21.1) | 1016 (21.4) | 1644 (21.5) | ||
| 4 | 601 (22.3) | 913 (22.5) | 1631 (23.0) | 326 (23.1) | 1028 (21.7) | 1788 (23.3) | ||
| 5 (least deprived) | 539 (20.0) | 864 (21.3) | 1806 (25.5) | 286 (20.2) | 1061 (22.4) | 1859 (24.3) | ||
| Missing | 4 (0.1) | 11 (0.3) | 12 (0.2) | 1 (0.1) | 10 (0.2) | 16 (0.2) | ||
| RCS Charlson score | ||||||||
| 0 | 1543 (57.1) | 2366 (58.2) | 4243 (59.8) | 0.004* | 805 (56.9) | 2771 (58.4) | 4570 (59.5) | 0.357 |
| 1 | 829 (30.7) | 1132 (27.8) | 1948 (27.5) | 416 (29.4) | 1365 (28.8) | 2122 (27.6) | ||
| ≥2 | 329 (12.2) | 568 (14.0) | 900 (12.7) | 193 (13.6) | 611 (12.9) | 988 (12.9) | ||
| Performance status | ||||||||
| 0 | 1550 (60.6) | 2370 (65.2) | 3884 (64.9) | <0.001* | 804 (62.5) | 2635 (62.6) | 4362 (65.4) | 0.002* |
| 1 | 732 (28.6) | 1026 (28.2) | 1608 (26.9) | 350 (27.2) | 1229 (29.2) | 1779 (26.7) | ||
| ≥2 | 276 (10.8) | 237 (6.5) | 495 (8.3) | 133 (10.3) | 343 (8.2) | 529 (7.9) | ||
| Missing | 143 (5.3) | 433 (10.6) | 1104 (15.6) | 127 (9.0) | 540 (11.4) | 1010 (13.2) | ||
| ASA grade | ||||||||
| 1 | 405 (15.7) | 597 (15.5) | 1004 (14.9) | 0.04* | 209 (15.5) | 708 (15.6) | 1087 (15.0) | 0.893 |
| 2 | 1524 (59.0) | 2408 (62.3) | 4128 (61.3) | 816 (60.5) | 2768 (60.8) | 4468 (61.5) | ||
| ≥3 | 652 (25.3) | 859 (22.2) | 1606 (23.8) | 323 (24.0) | 1074 (23.6) | 1713 (23.6) | ||
| Missing | 120 (4.4) | 202 (5.0) | 353 (5.0) | |||||
| Surgical access | ||||||||
| Open | 580 (21.6) | 1058 (26.1) | 1952 (27.6) | <0.001* | 430 (30.6) | 1500 (31.7) | 1646 (21.5) | <0.001 |
| Laparoscopic | 2052 (76.3) | 2758 (68.0) | 4654 (65.8) | 959 (68.2) | 3110 (65.7) | 5392 (70.4) | ||
| Robotic | 56 (2.1) | 238 (5.9) | 463 (6.5) | 18 (1.3) | 122 (2.6) | 617 (8.1) | ||
| Missing | 13 (0.5) | 12 (0.3) | 22 (0.3) | |||||
| Surgical urgency | ||||||||
| Elective/scheduled | 2582 (95.8) | 3858 (95.3) | 6894 (97.6) | <0.001* | 1307 (92.7) | 4574 (96.6) | 7447 (97.4) | <0.001* |
| Emergency/urgent | 113 (4.2) | 191 (4.7) | 173 (2.5) | 103 (7.3) | 161 (3.4) | 202 (2.6) | ||
| Missing | 6 (0.2) | 17 (0.4) | 24 (0.3) | 4 (0.3) | 12 (0.3) | 31 (0.4) | ||
| Surgical procedure | ||||||||
| Anterior resection | 1759 (65.1) | 2554 (62.8) | 4468 (63.0) | <0.001* | 883 (62.4) | 2977 (62.7) | 4917 (64.0) | <0.001* |
| APR | 629 (23.3) | 1038 (25.5) | 1778 (25.1) | 315 (22.3) | 1202 (25.3) | 1925 (25.1) | ||
| Hartmann's | 279 (10.3) | 402 (9.9) | 663 (9.3) | 181 (12.8) | 490 (10.3) | 664 (8.6) | ||
| Pelvic exenteration | 4 (0.1) | 22 (0.5) | 88 (1.2) | 8 (0.6) | 16 (0.3) | 90 (1.2) | ||
| Panproctocolectomy | 30 (1.1) | 50 (1.2) | 94 (1.3) | 27 (1.9) | 62 (1.3) | 84 (1.1) | ||
| Pathological T‐stage | ||||||||
| T1 | 320 (12.7) | 465 (12.3) | 914 (14.0) | 0.211 | 140 (10.8) | 582 (13.1) | 976 (13.8) | 0.05 |
| T2 | 715 (28.5) | 1130 (29.8) | 1866 (28.5) | 361 (27.7) | 1308 (29.4) | 2038 (28.8) | ||
| T3 | 1278 (50.9) | 1910 (50.4) | 3259 (49.8) | 689 (53.0) | 2213 (49.8) | 3543 (50.0) | ||
| T4 | 200 (8.0) | 282 (7.4) | 502 (7.7) | 111 (8.5) | 340 (7.7) | 526 (7.4) | ||
| Missing | 188 (7.0) | 279 (6.9) | 550 (7.8) | 113 (8.0) | 304 (6.4) | 597 (7.8) | ||
| Pathological N‐stage | ||||||||
| N0 | 1592 (63.7) | 2407 (63.4) | 4168 (63.7) | 0.231 | 825 (63.5) | 2818 (63.5) | 4515 (63.7) | 0.002* |
| N1 | 657 (26.3) | 942 (24.8) | 1632 (25.0) | 335 (25.8) | 1120 (25.3) | 1773 (25.0) | ||
| N2 | 251 (10.0) | 445 (11.7) | 741 (11.3) | 139 (10.7) | 497 (11.2) | 799 (11.3) | ||
| Missing | 201 (7.4) | 272 (6.7) | 550 (7.8) | 115 (8.1) | 312 (6.6) | 593 (7.7) | ||
| Pathological M‐stage | ||||||||
| M0 | 2344 (95.5) | 3612 (96.4) | 6041 (96.1) | 0.151 | 1198 (94.6) | 4160 (95.9) | 6628 (96.5) | 0.002* |
| M1 | 111 (4.5) | 133 (3.6) | 242 (3.9) | 69 (5.4) | 179 (4.1) | 237 (3.5) | ||
| Missing | 246 (9.1) | 321 (7.9) | 808 (11.4) | 147 (10.4) | 408 (8.6) | 815 (10.6) | ||
| Radiotherapy | ||||||||
| No radiotherapy | 1750 (64.8) | 2670 (65.7) | 4752 (67.0) | 0.013* | 957 (67.7) | 3097 (65.2) | 5105 (66.5) | <0.001* |
| Long course | 710 (26.3) | 1081 (26.6) | 1849 (26.1) | 338 (23.9) | 1246 (26.2) | 2053 (26.7) | ||
| Short course | 241 (8.9) | 315 (7.7) | 490 (6.9) | 119 (8.4) | 404 (8.5) | 522 (6.8) | ||
Abbreviations: APR, abdominoperineal resection; ASA, American Society of Anesthesologists; IMDQ, index of multiple deprivation quintiles; RCS, Royal College of Surgeons.
*Statistically significant p‐value <0.05.