Demographic characteristics of patients with IBD after the first data download on 17 July 2014, per university medical centre
| Total | MUMC | VUMC | AMC | UMCG | UMCU | EMC | LUMC | UMCN | |
| n | 3388 | 373 | 369 | 405 | 625 | 524 | 260 | 458 | 374 |
| CD | 2118 | 219 | 206 | 264 | 344 | 337 | 194 | 310 | 244 |
| UC/IBD-U/IBD-I | 1270 | 154 | 163 | 141 | 281 | 187 | 66 | 148 | 130 |
| Sex (F/M%) | 59/41 | 54/46 | 64/36 | 57/43 | 59/41 | 58/42 | 64/36 | 58/42 | 64/36 |
| Age at diagnosis* | 26 (20–37) | 31 (22–44) | 28 (21–37) | 26 (20–35) | 27 (21–39) | 25 (19–35) | 23 (18–30) | 26 (20–34) | 27 (20–37) |
| Disease duration* | 12 (5–20) | 8 (2–17) | 11 (6–20) | 13 (6–22) | 8 (4–15) | 14 (6–24) | 12 (6–20) | 15 (7–23) | 14 (7–24) |
*Median years with 25%–75% IQR.
AMC, Amsterdam Medical Centre; CD, Crohn’s disease; EMC, Erasmus Medical Centre; F, female; IBD, inflammatory bowel disease; IBD-I, inflammatory bowel disease-indeterminate; IBD-U, inflammatory bowel disease-unclassified; LUMC, Leiden University Medical Centre; M, male; MUMC, Maastricht University Medical Centre; UC, ulcerative colitis; UMCG, University Medical Center Groningen; UMCN, Radboud University Nijmegen Medical Centre; UMCU, University Medical Centre Utrecht; VUMC, VU (Vrije Universiteit) University Medical Centre (Amsterdam).