Table 1.
Baseline characteristics of patients with irritable bowel syndrome (IBS) and matched controls
| Patients undergoing colonoscopy | Patients undergoing upper endoscopy | Patients undergoing colonoscopy compared to siblings | ||||
|---|---|---|---|---|---|---|
| Characteristic | IBS (n=21,944) | Matched controls (n=97,468) | IBS (n=9,965) | Matched controls (n=46,313) | IBS (n=1,240) | Siblings (n=1,415) |
| Women, no. (%) | 15 213 (69.3%) | 68 358 (70.1%) | 7 199 (72.2%) | 33 990 (73.4%) | 876 (70.6%) | 790 (55.8%) |
| Men, no (%) | 6 731 (30.7%) | 29 110 (29.9%) | 2 766 (27.8%) | 12 323 (26.6%) | 364 (29.4%) | 625 (44.2%) |
| Age, years | ||||||
| Mean (SD) | 44.7 (17.0) | 45.7 (17.0) | 41.9 (16.8) | 42.5 (16.8) | 48.3 (15.6) | 50.1 (16.2) |
| Median (IQR) | 43.2 (30.0–57.7) | 44.8 (30.9–58.9) | 39.3 (27.3–54.2) | 40.2 (27.6–55.1) | 50.4 (35.3–61.1) | 52.6 (36.3–63.8) |
| Range, min-max | 18.0–96.1 | 18.0–97.2 | 18.0–93.3 | 18.0–92.7 | 18.1–81.9 | 18.3–80.5 |
| Categories, no. (%) | ||||||
| 18y - <30y | 5 495 (25.0%) | 22 750 (23.3%) | 3 110 (31.2%) | 13 957 (30.1%) | 215 (17.3%) | 225 (15.9%) |
| 30y - <40y | 4 137 (18.9%) | 17 360 (17.8%) | 2 013 (20.2%) | 9 045 (19.5%) | 177 (14.3%) | 186 (13.1%) |
| 40y - <50y | 4 015 (18.3%) | 17 673 (18.1%) | 1 713 (17.2%) | 8 063 (17.4%) | 223 (18.0%) | 222 (15.7%) |
| 50y - <60y | 3 637 (16.6%) | 17 084 (17.5%) | 1 447 (14.5%) | 7 007 (15.1%) | 287 (23.1%) | 294 (20.8%) |
| 60y - <70y | 2 775 (12.6%) | 13 527 (13.9%) | 995 (10.0%) | 4 922 (10.6%) | 257 (20.7%) | 344 (24.3%) |
| ≥70y | 1 885 (8.6%) | 9 074 (9.3%) | 687 (6.9%) | 3 319 (7.2%) | 81 (6.5%) | 144 (10.2%) |
| Country of birth, no (%) | ||||||
| Nordic country | 19 982 (91.1%) | 86 388 (88.6%) | 8 953 (89.8%) | 38 520 (83.2%) | 1 213 (97.8%) | 1 378 (97.4%) |
| Other | 1 961 (8.9%) | 11 078 (11.4%) | 1 012 (10.2%) | 7 791 (16.8%) | 27 (2.2%) | 37 (2.6%) |
| Level of education, no (%) | ||||||
| ≤9 years | 4 159 (19.0%) | 19 632 (20.1%) | 1 803 (18.1%) | 10 097 (21.8%) | 249 (20.1%) | 356 (25.2%) |
| 10–12 years | 10 636 (48.5%) | 45 079 (46.3%) | 4 839 (48.6%) | 21 604 (46.6%) | 571 (46.0%) | 651 (46.0%) |
| >12 years | 7 032 (32.0%) | 32 051 (32.9%) | 3 255 (32.7%) | 14 168 (30.6%) | 419 (33.8%) | 403 (28.5%) |
| Missing | 117 (0.5%) | 706 (0.7%) | 68 (0.7%) | 444 (1.0%) | 1 (0.1%) | 5 (0.4%) |
| Year of index biopsy, no. (%) | ||||||
| 1987–1996 | 428 (2.0%) | 1 641 (1.7%) | 380 (3.8%) | 1 653 (3.6%) | 6 (0.5%) | 23 (1.6%) |
| 1997–2006 | 8 447 (38.5%) | 37 373 (38.3%) | 4 229 (42.4%) | 19 788 (42.7%) | 446 (36.0%) | 470 (33.2%) |
| 2007–2011 | 7 473 (34.1%) | 33 367 (34.2%) | 3 151 (31.6%) | 14 663 (31.7%) | 480 (38.7%) | 522 (36.9%) |
| 2012–2016 | 5 596 (25.5%) | 25 087 (25.7%) | 2 205 (22.1%) | 10 209 (22.0%) | 308 (24.8%) | 400 (28.3%) |
| ≥1997 | 21 516 (98.0%) | 95 827 (98.3%) | 9 585 (96.2%) | 44 660 (96.4%) | 1 234 (99.5%) | 1 392 (98.4%) |
| Months between IBS diagnosis and index biopsy | ||||||
| Mean (SD) | 0.7 (1.3) | 1.2 (1.5) | 0.8 (1.3) | |||
| Median (IQR) | 0.1 (0.0–0.9) | 0.4 (0.0–1.9) | 0.1 (0.0–0.9) | |||
| Range, min-max | 0.0–6.0 | 0.0–6.0 | 0.0–6.0 | |||
| Disease history within 5 years before biopsy, no (%) | ||||||
| Cardiovascular disease (CVD) | 3 635 (16.6%) | 17 424 (17.9%) | 1 440 (14.5%) | 6 517 (14.1%) | 225 (18.1%) | 313 (22.1%) |
| Cardiovascular disease in inpatient care | 2 051 (9.3%) | 10 032 (10.3%) | 846 (8.5%) | 4 326 (9.3%) | 125 (10.1%) | 190 (13.4%) |
| Cancer (excluding CRC) | 725 (3.3%) | 9 779 (10.0%) | 285 (2.9%) | 2 485 (5.4%) | 50 (4.0%) | 156 (11.0%) |
| Diabetes | 791 (3.6%) | 3 857 (4.0%) | 314 (3.2%) | 1 905 (4.1%) | 56 (4.5%) | 80 (5.7%) |
| Neurologic disease | 2 114 (9.6%) | 7 875 (8.1%) | 892 (9.0%) | 3 524 (7.6%) | 138 (11.1%) | 148 (10.5%) |
| IBS subtype (in biopsies ≥1997), no. (%) | ||||||
| IBS with diarrhea | 13 434 (62.4%) | 5 260 (54.9%) | 796 (64.5%) | |||
| IBS without diarrhea | 8 057 (37.4%) | 4 309 (45.0%) | 436 (35.3%) | |||
| IBS unspecified | 25 (0.1%) | 16 (0.2%) | 2 (0.2%) | |||
| IBS as main diagnosis, no. (%) | ||||||
| Yes | 19 615 (89.4%) | 8 363 (83.9%) | 1 086 (87.6%) | |||
| No | 2 329 (10.6%) | 1 602 (16.1%) | 154 (12.4%) | |||
| Deaths, no. (%) | ||||||
| ≤30 days after index date | 15 (0.1%) | 244 (0.3%) | 10 (0.1%) | 181 (0.4%) | 0 | 4 (0.3%) |
| ≤90 days after index date | 40 (0.2%) | 708 (0.7%) | 31 (0.3%) | 427 (0.9%) | 1 (0.1%) | 14 (1.0%) |
| ≤365 days after index date | 148 (0.7%) | 2 079 (2.1%) | 84 (0.8%) | 1 122 (2.4%) | 4 (0.3%) | 29 (2.0%) |
†
Both IBS patients and their matched controls were excluded from all analyses if at baseline they had an earlier diagnosis of inflammatory bowel disease, celiac disease, microscopic colitis, precancerous polyps or colorectal cancer up until −7 days from the index biopsy since these disorders may lead to false-positive IBS diagnoses.
***
Conditioned on matching set and further adjusted for age, sex, education and baseline medical comorbidities (cancer, diabetes, CVD, and neurologic disease)