Cholecystectomy and the risk of alimentary tract cancers: A systematic review

Table 7 Descriptive characteristics of studies on the association between cholecystectomy and liver cancer

Ref.	Period of study	Study design	No. of cases	No. of controls	Exposure ascertainment	Outcome ascertainment	Follow-up (yr)	Effect estimate	Adjustments	Quality of publication
Nogueira et al[21], 2014	1992-2005	Case-control	332/10219	2572/100000	Medicare database	Cancer registry	> 6	OR = 1.23 (1.15-1.33)	Age, gender, diabetes	49
Chow et al[34], 1999	1977-1993	Cohort	48/42461	NA	National registry	Cancer registry	≥ 4	1.1 (0.7-1.5)	Age, gender, obesity, years of follow-up, other comorbidities	33
Goldacre et al[22], 2005	1963-1999	Cohort	38/39245	306/334813	NHS database	Cancer registry	NA	0.91 (0.64-1.25)	Age, gender, calendar year, residence	36
Chen et al[29], 2014	2000-2010	Cohort	87/5850	163/5850	National database	Cancer registry	10	1.17 (0.90-1.52)	Age, gender, comorbidities	53

NA: Not available.