Table 2. Pooled analysis of association of metformin use and survival of PC concurrent with DM.

	N	Sample size	HR	Ph	I2
Total	10	9318	0.84	0.006	60.8%
			(0.73-0.96)
Country
Asian	3	544	0.65(0.52-0.80)	0.83	0.0%
Western	7	8774	0.90(0.78-1.03)	0.028	57.6%
Quality
High	7	8495	0.81(0.70-0.95)	0.012	63.3%
Low	3	823	0.88(0.60-1.29)	0.67	63.1%
Exposure
Before PC diagnose	3	4740	1.00(0.81-1.24)	0.1	56.6%
After PC diagnose	3	2359	0.76(0.52-1.11)	0.028	72.0%
Publication bias test
Begg's test		p=1.00
Egger's test		p=0.896

P_h: P for heterogeneity.