Video capsule endoscopy vs double-balloon enteroscopy in the diagnosis of small bowel bleeding: A systematic review and meta-analysis

Table 1 QUADAS-2. Risk of bias in individual studies

Study	Hadithi et al, 2006[4]	Hermans et al, 2017[11]	Holleran et al, 2014[37]	Kaffes et al, 2007[34]	Kalra et al, 2015[16]	Kamalapor et al, 2008[30]	Kameda et al, 2008[27]	Li et al, 2010[35]	Lin et al, 2007[40]	Maeda et al, 2015[32]	Marmo et al, 2009[23]	TianMin, et al, 2013[39]	Nakamura et al, 2006[29]	Rahmi et al, 2013[33]	Chu et al, 2016[17]	Zhang, et al, 2015[15]
Was a consecutive or random sample of patients enrolled?	YES	UNCLEAR	UNCLEAR	YES	UNCLEAR	UNCLEAR	YES	YES	YES	YES	YES	YES	YES	YES	YES	UNCLEAR
Was a case-control design avoided?	YES	YES	NO	YES	YES	NO	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES
Did the study avoid inappropriate exclusions?	YES	YES	YES	YES	UNCLEAR	NO	YES	YES	YES	YES	YES	YES	YES	YES	YES	NO
Could the selection of patients have introduced bias?	LOW	MODERATE	HIGHT	LOW	HIGH	HIGH	LOW	LOW	LOW	LOW	LOW	LOW	LOW	LOW	LOW	HIGH
Are there concerns that the included patients do not match the review question?	LOW	LOW	LOW	LOW	LOW	LOW	LOW	LOW	LOW	LOW	LOW	LOW	LOW	LOW	LOW	HIGH
Were the index test results interpreted without knowledge of the results of the reference standard?	YES	NO	YES	NO	YES	NO	YES	UNCLEAR	UNCLEAR	UNCLEAR	YES	NO	YES	NO	NO	UNCLEAR
If a threshold was used, was it prespecified? Could the conduct or interpretation of the index test have introduced bias?	YES LOW	YES MODERATE	YES LOW	YES MODERATE	NO MODERATE	YES MODERATE	YES LOW	YES MODERATE	NO MODERATE	YES MODERATE	YES LOW	NO HIGH	YES LOW	YES MODERATE	YES MODERATE	YES MODERATE
Are there concerns that the index test, its conduct, or interpretation differ from the review question?	LOW	LOW	LOW	LOW	LOW	LOW	LOW	LOW	LOW	LOW	LOW	LOW	LOW	LOW	LOW	HIGH
Is the reference standard likely to correctly classify the target condition?	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	NO	UNCLEAR
Were the reference standard results interpreted without knowledge of the results of the index test?	YES	NO	YES	NO	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	UNCLEAR
Could the reference standard, its conduct, or its interpretation have introduced bias?	LOW	MODERATE	LOW	MODERATE	LOW	LOW	LOW	LOW	LOW	LOW	LOW	LOW	LOW	LOW	HIGH	HIGH
Are there concerns that the target condition as defined by the reference standard does not match the review question?	LOW	LOW	LOW	LOW	LOW	LOW	LOW	LOW	LOW	LOW	LOW	LOW	LOW	LOW	HIGH	HIGH
Was there an appropriate interval between index test(s) and reference standard?	YES	NO	NO	NO	NO	NO	YES	YES	YES	YES	YES	YES	YES	NO	YES	UNCLEAR
Did all patients receive a reference standard?	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES
Did all patients receive the same reference standard?	NO	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES
Were all patients included in the analysis?	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES
Could the patient flow have introduced bias?	MODERATE	LOW	LOW	LOW	LOW	MODERATE	LOW	LOW	LOW	LOW	LOW	LOW	LOW	MODERATE	LOW	LOW