Table 4. Incidence rate of IBD after IBS diagnosis and the incidence rate ratio.

Current age	Time since IBS diagnosis	IBS population						Control population						Rate ratio	95% CI
		n †	% ‡	N ††	Person time (years)	Incidence rate (per 10000 person years)	95% CI	n †	% ‡	N ††	Person time (years)	Incidence rate (per 10000 person years)	95% CI
18–29	0–6 months	87	0.32	26789	12596	69.1	56.0–85.2	14	0.01	126414	49652	2.8	1.7–4.8	24.5	13.9–43.1
	6–12 months	45	0.17	26578	11010	40.9	30.5–54.7	9	0.01	80793	34527	2.6	1.4–5.0	15.7	7.7–32.1
	1–5 years	100	0.49	20472	48266	20.7	17.0–25.2	23	0.04	59180	104129	2.2	1.5–3.3	9.4	6.0–14.8
	5–10 years	20	0.33	6027	12669	15.8	10.2–24.5	6	0.06	9607	18946	3.2	1.4–7.1	5.0	2.0–12.4
	10 years to end of follow–up	1	0.22	458	389	25.7	3.6–182.6	1	0.14	729	621	16.1	2.3–114.3	1.6	0.1–25.5
30–49	0–6 months	137	0.28	49455	23624	58.0	49.1–68.6	30	0.01	250082	108046	2.8	1.9–4.0	20.9	14.1–31.0
	6–12 months	78	0.17	47191	22459	34.7	27.8–43.4	21	0.01	198503	89613	2.3	1.5–3.6	14.8	9.2–24.0
	1–5 years	195	0.39	49500	139731	14.0	12.1–16.1	90	0.05	177732	404694	2.2	1.8–2.7	6.3	4.9–8.1
	5–10 years	72	0.24	29513	89988	8.0	6.4–10.1	51	0.08	62018	162675	3.1	2.4–4.1	2.6	1.8–3.7
	10 years to end of follow–up	30	0.27	10945	35455	8.5	5.9–12.1	11	0.07	15130	42675	2.6	1.4–4.7	3.3	1.7–6.6
50 and older	0–6 months	74	0.20	37117	17689	41.8	33.3–52.5	20	0.01	177232	80144	2.5	1.6–3.9	16.8	10.2–27.5
	6–12 months	34	0.09	36285	17272	19.7	14.1–27.5	22	0.01	157305	72650	3.0	2.0–4.6	6.5	3.8-11.1
	1–5 years	160	0.37	43224	122965	13.0	11.1–15.2	147	0.09	168697	425404	3.5	2.9–4.1	3.8	3.0–4.7
	5–10 years	101	0.30	34179	108384	9.3	7.7–11.3	89	0.09	97062	274856	3.2	2.6–4.0	2.9	2.2–3.8
	10 years to end of follow-up	50	0.25	19916	71811	7.0	5.3–9.2	35	0.09	39420	124469	2.8	2.0–3.9	2.5	1.6–3.8

Incident rate ratios in bold are statistically significant and have a p-value <0.05.

^† n is the number of people diagnosed with IBD within the stratum;

^‡% is the proportion that these diagnoses represent within the stratum;

^††N is the total number of patients contributing time to the stratum. The rates are split by time since IBS was diagnosed and the current age of the patient. This means, for example, that the risk of IBD for someone who is 34 and was diagnosed with IBS 6 years ago can be seen as 2.6 times greater than someone without IBS.