. 2005 Aug;54(8):1121–1125. doi: 10.1136/gut.2004.049460

Table 1.

Summary of studies included in the meta-analysis

	Connell¹⁴	Farrell¹⁵	Fraser¹⁶	Kinlen¹²	Korelitz¹⁷	Lewis¹
Year	1994	2000	2002	1985	1999	2001
Setting	Single centre	Single centre	Single centre	Single centre	Single centre	Population based
Total No of IBD patients	755	238*	626	321	486	1465
% with CD	60	46	43	N/R	67	57
% with UC	40	54	57	N/R	33	43
Mean/median duration of treatment	12.5 mo	1.82 y	2.26 y	N/R	4.4 y	2 y
Medication studied	AZA	AZA	AZA	AZA	6-MP	AZA
Mean/median dose or range	2 mg/kg/day	2–2.5 mg/kg/day	1.65 mg/kg/day	N/R	12.5–100 g/day	106 mg/day
Mean/median duration of follow up	9 y	6.9 y	6.9 y	N/R	5.9 y	2.87 y
Outcome	NHL	NHL	NHL and HD	NHL	NHL and HD	NHL and HD
Expected No of lymphomas	0.52	0.05	0.65	0.16	0.61	0.64
Observed No of lymphomas	0	2†	3	2	3	1
SIR‡ (95% CI)	0 (—)	37.5 (3.5–137.7)	4.6 (0.9–13.7)	12.5 (1.2–46.0)	4.9 (0.9–14.5)	1.6 (0.0006–9.0)

IBD, inflammatory bowel disease; UC, ulcerative colitis; CD, Crohn’s disease; NHL, non-Hodgkin lymphoma; HD, Hodgkin’s disease; AZA, azathioprine; 6-MP, 6-mercaptopurine; 95% CI, 95% confidence interval.

*Treated with immunomodulators.

†Two additional lymphomas observed in patients treated with methotrexate and ciclosporin.

N/R, not reported.

‡SIR, standardised incidence ratio for lymphoma. Because of rounding of the expected number of lymphomas, SIR does not exactly equal observed number of lymphomas divided by expected number of lymphomas.