Table 1. Characteristics of eligible studies.

Number	First author	Year	Country	Ethnicity	Sample size		Source of control groups	Genotyping method	Adjusted factors	Citation
					Case	Control
1	Khorshidi et al.	2017	Iran	Asian	122	200	PB	T-ARMS-PCR	Age	[11]
2	Kang et al.	2015	China	Asian	380	380	HB	MALDI-TOF MS	Age, sex, and drinking status	[12]
3	Taheri et al.	2017	Iran	Asian	125	220	PB	T-ARMS-PCR	Age, BMI, and smoking history	[13]
4	Peng et al.	2017	China	Asian	487	489	PB	PCR-RFLP, CRS-RFLP	Age	[14]
5	Liu et al.	2012	China	Asian	1300	1344	PB	TaqMan Assay-PCR	Age, sex, smoking rate, and HBV chronic infection	[15]
6	Li et al.	2017	China	Asian	821	857	HB	MassARRAY	Age, sex, BMI, smoking, and alcohol drinking	[16]
7	Gong et al.	2016	China	Asian	498	213	HB	MassARRAY	Age and sex	[17]
8	Hu et al.	2017	China	Asian	921	921	PB	TaqMan Assay-PCR	Age, sex, and area of residence	[18]
9	Shaker et al.	2017	Egypt	Caucasian	120	96	PB	TaqMan Assay-PCR	Age and sex	[19]
10	He et al.	2017	China	Asian	494	494	HB	MassARRAY	Helicobacter pylori infection rate, age, sex, and smoking and drinking status	[20]
11	Duan et al.	2017	China	Asian	470	470	HB	PCR-RFLP	Age, sex, and drinking	[6]
12	Li et al.	2016	China	Asian	219	394	HB	PCR-RFLP	Age and sex	[21]
13	Sattarifard et al.	2017	Iran	Asian	178	180	HB	PCR-RFLP	Age	[22]
14	Li et al.	2013	China	Asian	313	595	HB	PCR-RFLP	Age and sex	[23]
15	Chung et al.	2010	Japan	Asian	1504	1554	HB	Multiplex PCR-based Invader	NM	[24]
16	Salinas et al.	2008	U.S.A.	Caucasian	1308	1266	PB	SNPlex genotyping system	Age	[25]
17	Zheng et al.	2010	China	Asian	288	155	PB	MassARRAY	Age, sex, and BMI	[26]

Abbreviations: BMI, body mass index; HB, hospital based; NM, not mentioned; PB, population based.