Statin use and risk of liver cancer: A meta-analysis of 7 studies involving more than 4.7 million patients

Table 2 Subgroup analyses of included studies

Subgroup	No. of studies	Fixed-effects model			Random-effects model			Heterogeneity
		RR	95%CI	P value	RR	95%CI	P value	Q	P	I2(%)
Type of design of studies
Case-control	3	0.69	0.60-0.79	< 0.001	0.63	0.49-0.82	< 0.001	4.75	0.093	57.9
Cohort	4	0.56	0.47-0.66	< 0.001	0.62	0.43-0.89	0.01	10.74	0.013	72.1
Country or area
Asian	3	0.51	0.43-0.62	< 0.001	0.51	0.42-0.63	< 0.001	2.30	0.317	13.0
Euro- American	4	0.71	0.62-0.80	< 0.001	0.71	0.52-0.95	0.023	9.14	0.028	67.2
Confounding adjustment
Adequately1	3	0.65	0.58-0.74	< 0.001	0.61	0.46-0.81	0.001	8.64	0.013	76.8
Inadequately	4	0.59	0.48-0.73	< 0.001	0.63	0.41-0.95	0.028	9.82	0.020	69.4
Study population
General population	5	0.60	0.50-0.71	< 0.001	0.62	0.46-0.83	0.001	9.89	0.042	59.5
Restricted to specified patients2	2	0.66	0.58-0.75	< 0.001	0.60	0.38-0.93	0.023	8.50	0.004	88.2

¹The confounding factors would be regarded as been controlled adequately when these 5 factors had been controlled, including age, sex, HBV infection, HCV infection and alcohol liver disease;

²The study population of two studies was restricted to specified patients, including patients with diabetes mellitus (Ref. 37) and those with HBV infection (Ref. 18). RR: Relative risk; HBV: Hepatitis B virus; HCV: Hepatitis C virus.