Table 1

Characteristics of the Danish nationwide study cohort (1977–2014)

Characteristics	Individuals diagnosed with CD		Non-IBD individuals		Individuals diagnosed with UC		Non-IBD individuals
Characteristics	n	%	n	%	n	%	n	%
Total	24 594		2 547 429		51 822		4 927 119
Gender
Female	14 195	57.7	1 299 156	51.0	27 410	52.9	2 374 342	48.2
Male	10 399	42.3	1 248 273	49.0	24 357	47.1	2 522 777	51.8
Comorbidity index
0	12 315	50.1	1 741 926	68.4	25 361	49.0	2 948 994	59.9
1–2	7188	29.2	510 825	20.1	14 994	29.0	1 197 925	24.3
3–4	2860	11.6	168 551	6.6	6467	12.5	450 197	9.1
5–6	1 768	7.2	106 586	4.2	3921	7.6	278 940	5.7
>7	463	1.9	19 541	0.8	1024	2.0	51 063	1.0
Age at IBD diagnosis (years)*
<40	13 477	54.8	1 603 750	62.9	22 105	42.7	2 369 365	48.1
40–65	7095	28.8	599 045	23.5	18 019	34.8	1 500 711	30.5
>65	4022	16.4	344 634	13.5	11 643	22.5	1 057 043	21.5
Year at IBD diagnosis†
1977–1984	2971	12.1	405 671	15.9	6935	13.4	1 092 950	22.2
1985–1994	4627	18.8	482 049	18.9	8672	16.8	833 817	16.9
1995–2005	7234	29.4	653 038	25.6	15 635	30.2	1 296 167	26.3
2005–2014	9 762	39.7	1 006 671	39.5	20 525	39.6	1 704 185	34.6

*Age at IBD diagnosis is age at matching for non-IBD individuals in the background cohort.
† Number of non-IBD individuals matched with patients with IBD diagnosed in the respective period. All eligible matches are chosen. A match can be matched to more than one patient with IBD.
CD, Crohn’s disease; UC, ulcerative colitis.