Table 2.

Subgroup analysis of relative risk for gallbladder cancer mortality in DM patients

Subgroup	No. of references	HR and 95% CI	Pa	I2%	Pb
Country
Western countries	4	1.09 (1.05–1.13)	< 0.0001	0%	0.29
Eastern countries	2	1.10 (1.06–1.13)	0.001	0%
Follow-up duration
≦10	4	1.03 (0.89–1.20)	0.70	84%	0.27
> 10	3	1.13 (1.06–1.21)	0.0005	0%
Diabetes assessment
Self-report	3	1.14 (1.06–1.22)	0.0003	0%	0.34
Medical record	3	1.01 (0.81–1.27)	0.92	73%
Adjusted BMI
Yes	3	1.14 (1.07–1.21)	< 0.0001	0%	0.30
No	5	1.04 (0.90–1.21)	0.57	78%
Adjusted smoking
Yes	4	1.10 (1.05–1.14)	< 0.0001	0%	0.63
No	4	1.05 (0.87–1.26)	0.64	44%
Adjusted education
Yes	2	1.13 (1.05–1.21)	0.0007	0%	0.43
No	6	1.06 (0.93–1.21)	0.35	78%

P_a P value for heterogeneity within subgroup, P_b P value for subgroup differences