Smoking, alcohol consumption, and the risk of extrahepatic cholangiocarcinoma: A meta-analysis

Table 3 Subgroup analyses of the association between smoking and extrahepatic cholangiocarcinoma and alcohol consumption and extrahepatic cholangiocarcinoma

	No. of studies	RR (95%CI)	Tests for heterogeneity
			Q	P	I2
Smoking
Geographical region
Non-Asia	7	1.39 (1.03-1.87)	8.280	0.218	27.5%
Asia	4	1.08 (0.85-1.38)	3.850	0.278	22.1%
Study design
Population-based	5	1.47 (1.06-2.05)	5.470	0.243	26.8%
Hospital-based	6	1.10 (0.88-1.37)	6.190	0.288	19.2%
Adjustment for cholelithiasis	3	1.28 (0.94-1.76)	1.917	0.383	0.0%
Alcohol drinking
Geographical region
Non-Asia	4	0.94 (0.56-1.56)	3.560	0.313	15.7%
Asia	3	1.17 (0.90-1.53)	0.360	0.835	0.0%
Study design
Population-based	2	0.92 (0.44-1.94)	2.890	0.089	65.4%
Hospital-based	4	1.16 (0.86-1.58)	1.520	0.678	0.0%
Case-control	6	1.10 (0.86-1.41)	4.750	0.447	0.0%
Cohort	1	1.06 (0.60-1.87)	-	-	-