Table 5.

 Malignant lymphomas 1969–2001 in a combined population based cohort of 47 679 Swedish patients with inflammatory bowel disease

	Ulcerative colitis					Crohn’s disease
	O	E	SIR (95% CI)	RR	p Value	O	E	SIR (95% CI)	RR	p Value
Overall	87	84	1.0 (0.8–1.3)	–	–	65	50	1.3 (1.0–1.6)	–	–
Sex
Male	50	53	0.9 (0.7–1.2)	1 (ref)	0.29	42	29	1.5 (1.1–2.0)	1 (ref.)	0.20
Female	37	31	1.2 (0.8–1.6)	1.3 (0.8–1.9)		23	22	1.1 (0.7–1.6)	0.7 (0.4–1.2)
Cohort of origin
Any regional cohort	19	23	0.8 (0.5–1.3)	0.8 (0.5–1.5)	0.56	18	14	1.3 (0.8–2.0)	1.0 (0.6–2.0)	0.76
Inpatient register only	68	62	1.1 (0.9–1.4)	1 (ref)		47	36	1.3 (1.0–1.7)	1 (ref.)
Calendar period at follow up
–1979	4	5.8	0.7 (0.2–1.8)	1 (ref)	0.63	5	3.1	1.6 (0.5–3.8)	1 (ref.)	0.34
1980–1989	24	22	1.1 (0.7–1.6)	1.6 (0.5–4.5)		11	12	0.9 (0.5–1.6)	0.6 (0.2–1.8)
1990–2001	59	57	1.0 (0.8–1.3)	1.6 (0.5–4.5)		49	35	1.4 (1.0–1.8)	1.0 (0.4–2.6)
Time of follow up (y)
1–5	36	26	1.4 (1.0–1.9)	1.4 (0.8–2.3)	0.09	23	14	1.6 (1.0–2.4)	1.1 (0.5–2.2)	0.42
6–10	14	19	0.7 (0.4–1.2)	0.7 (0.4–1.4)		12	12	1.0 (0.5–1.8)	1.0 (0.4–1.6)
⩾11	37	39	1.0 (0.7–1.3)	1 (ref)		30	25	1.2 (0.8–1.8)	1 (ref.)

First year of follow up excluded.

Observed (O) and expected (E) number of malignant lymphomas, standardised incidence ratio (SIR) with 95% confidence intervals (95% CI), and multivariate relative risks (RR) from models including all parameters in table (“ref” denotes reference category).

p values refer to type 3 tests.