Table 5.

Adjusted odds ratio for IBD, CD and UC stratified by course, duration and year before diagnosis of antibiotic use

Antibiotic use	IBD				CD				UC
	Cases [n = 736]	Controls [n = 1472]	Adjusted OR	95% CI	Cases [n = 339]	Controls [n = 678]	Adjusted OR	95% CI	Cases [n = 397]	Controls [n = 794]	Adjusted OR	95% CI
No use [n]	281	977	Ref		127	437	Ref		154	540	Ref
Any use [n]	455	495	2.93	2.40–3.58	212	241	3.01	2.27–4.00	243	254	2.94	2.23–3.88
Courses
1–3 courses [n]	357	436	2.61	2.12–3.23	160	206	2.65	1.97–3.58	197	230	2.65	1.99–3.53
4–6 courses [n]	77	53	4.61	3.12–6.84	38	31	4.37	2.58–7.45	39	22	5.23	2.9 2–9.56
≥ 7 courses [n]	21	6	10.34	4.19–29.19	14	4	11.89	4.00–43.6	7	2	10.88	2.49–75.17
Duration†
1–14 days [n]	208	293	2.27	1.78–2.89	91	136	2.17	1.53–3.07	117	157	2.30	1.66–3.18
15–29 days [n]	19	130	2.64	1.94–3.61	51	62	2.98	1.92–4.59	58	68	2.66	1.73–4.08
≥ 30 days [n]	138	72	6.03	4.34–8.45	70	43	5.89	3.80–9.23	68	29	7.07	4.31–11.83
Year before diagnosis
1 year [n]	187	174	3.60	2.75–4.72	91	92	3.32	2.30–4.81	96	82	3.65	2.50–5.35
2 years [n]	101	140	2.44	1.79–3.30	50	67	2.74	1.78–4.21	51	73	2.37	1.54–3.63
3 years [n]	71	79	2.62	1.79–3.81	33	34	2.98	1.73–5.14	38	45	2.75	1.65–4.57
4 years [n]	53	51	3.00	1.94–4.63	20	26	2.69	1.41–5.06	33	25	3.26	1.80–5.94
> 4 years [n]	43	51	2.60	1.63–4.11	18	22	2.93	1.48–5.72	25	29	2.42	1.31–4.43

IBD, inflammatory bowel disease; CD, Crohn’s disease; UC, ulcerative colitis; OR, odds ratio; CI, confidence interval; Ref, reference.

†Cumulative duration of antibiotic use 3 months to 5 years before diagnosis.