Table 1 Characteristics for the study cohort of 709 353 patients followed for the development of Crohn's disease after an appendectomy in Swedish (1964–2004) and Danish (1977–2004) hospitals.
| Sweden | Denmark | Both countries | |
|---|---|---|---|
| No. patients (%) | No. patients (%) | No. patients (%) | |
| Sex | |||
| Male | 198 138 (44.6) | 113 336 (42.7) | 311 474 (43.9) |
| Female | 245 623 (55.4) | 152 256 (57.3) | 397 879 (56.1) |
| Year of appendectomy | |||
| 1964–1976 | 77 216 (17.4) | – | 77 216 (10.9) |
| 1977–1985 | 124 726 (28.1) | 110 879 (41.7) | 235 605 (33.2) |
| 1986–1994 | 125 263 (28.2) | 85 172 (32.1) | 210 435 (29.7) |
| 1995–2004 | 116 556 (26.3) | 69 541 (26.2) | 186 097 (26.2) |
| Age at appendectomy (years) | |||
| 0–9 | 34 092 (7.7) | 24 311 (9.2) | 58 403 (8.2) |
| 10–19 | 121 179 (27.3) | 76 966 (29.0) | 198 145 (27.9) |
| 20–29 | 91 317 (20.6) | 47 752 (18.0) | 139 069 (19.6) |
| 30–39 | 64 324 (14.5) | 36 493 (13.7) | 100 817 (14.2) |
| 40–49 | 51 027 (11.5) | 27 444 (10.3) | 78 471 (11.1) |
| ⩾50 | 81 822 (18.4) | 52 626 (19.8) | 134 448 (19.0) |
| Cause of appendectomy | |||
| Appendicitis | 296 367 (66.8) | 183 168 (69.0) | 479 535 (67.6) |
| With perforation | 54 934 (12.4) | 38 300 (14.4) | 93 234 (13.1) |
| Without perforation | 241 433 (54.4) | 144 868 (54.5) | 386 301 (54.5) |
| Mesenteric lymphadenitis | 24 064 (5.4) | 8119 (3.1) | 32 183 (4.5) |
| Other disease (non‐inflamed appendix) | 123 330 (27.8) | 74 305 (28.0) | 197 635 (7.9) |
| Appendiceal disease except appendicitis* | 1868 (0.4) | 1222 (0.5) | 3090 (0.4) |
| Non‐specific abdominal pain | 28 212 (6.4) | 13 433 (5.1) | 41 645 (5.9) |
| Other and unspecified disease | 93 250 (21.0) | 59 650 (22.5) | 152 900 (21.6) |
| Total | 443 761 (100) | 265 592 (100) | 709 353 (100) |
*Appendiceal disease except appendicitis includes neoplasm, mucocele, lymphoid hyperplasia, invagination, fecalith and fistula.