Table 2. Subgroup RR and 95% CI analysis of thiopurine usage and risk of colorectal neoplasm in patients with IBD (random-effect model).

	No. of studies	Study heterogeneity			RR(95% CI)	P value
		Q	P-value	I2
Study population
Non-referral	6	15.43	0.009	67.60%	0.57(0.27-1.19)	0.133
Clinic-based	13	35.17	0	65.90%	0.76(0.56-1.04)	0.082
Type of relative risk estimation
OR/RR	15	50.29	0	72.20%	0.68(0.47-1.00)	0.05
HR	4	5.8	0.122	48.30%	0.83(0.52-1.31)	0.417
Sample size
Smaller (<100)	4	1.04	0.791	0.00%	0.89(0.43-1.86)	0.762
Larger (≥100)	15	55.14	0	74.60%	0.69(0.51-0.94)	0.019
Longstanding IBD(≥7yrs)
Yes	6	4.98	0.418	0.00%	0.98(0.74-1.29)	0.863
No	13	54.16	0	77.80%	0.58(0.37-0.91)	0.017
Thiopurine therapy>6m
Yes	6	17.85	0.003	72.00%	0.56(0.22-1.42)	0.221
no	13	36.59	0	67.20%	0.74(0.55-0.99)	0.044
IBD type
UC only	9	13.94	0.083	42.60%	0.85(0.56-1.27)	0.413
Mixed	10	42.01	0	78.60%	0.61(0.39-0.95)	0.029
5-ASA usage adjusted/matched
Yes	6	22.96	0	78.20%	0.81(0.34-1.94)	0.627
No	13	28.16	0.005	57.40%	0.71(0.54-0.94)	0.018
Sex/age adjusted/matched
Yes	9	25.2	0.001	68.20%	0.69(0.39-1.29)	0.209
No	10	23.03	0.006	60.90%	0.74(0.54-1.02)	0.066
Disease duration/extent adjusted
Yes	9	18.96	0.015	57.80%	0.54(0.32-0.92)	0.023
No	10	16.16	0.064	44.30%	0.89(0.69-1.14)	0.34
Sex/age/duration/extent of disease adjusted/matched
Yes	8	17.26	0.016	59.50%	0.61(0.34-1.10)	0.098
No	11	24.33	0.007	58.90%	0.80(0.60-1.07)	0.127
Mean/median follow-up period
>5yr	11	16.82	0.083	39.80%	0.90(0.72-1.14)	0.386
unknown	8	14.08	0.05	50.3	0.48(0.28-0.82)	0.007
Geographic distribution
Europe	9	43.61	0	82.10%	0.60(0.37-0.97)	0.036
USA	8	11.64	0.113	39.80%	0.87(0.57-1.33)	0.529