Table 2.

Quality assessment of individual studies

Study	Study design	Spectrum biasa	Eligibility criteria clearly defined	Appropriate reference standard	Differential verification biasb	Index test and reference standard sufficiently described	Selective loss during followupc	Important confounders identified
Zheng et al. [6]	Prospective study	No	Yes	Yes	Yes	Yes	No	Yes
Sirota et al. [7]	Retrospective and prospective study	No	Yes	Yes	Yes	Yes	–	Yes
Li et al. [11]	Prospective study	No	Yes	Yes	Yes	Yes	No	Yes
Chen et al. [12]	Prospective study	No	No	Yes	Yes	Yes	No	Yes
Parikh et al. [13]	Prospective, multicenter cohort study	No	Yes	Yes	Yes	Yes	No	Yes
Parikh et al. [14]	Prospective, multicenter cohort study	No	Yes	Yes	Yes	Yes	No	Yes
Endre et al. [15]	Prospective observational study	No	Yes	Yes	Yes	Yes	No	Yes
Liangos et al. [16]	Prospective cohort study	No	Yes	Yes	Yes	Yes	No	Yes
Washburn et al. [17]	Prospective study	No	Yes	Yes	Yes	Yes	No	Yes
Parikh et al. [18]	Prospective study	No	Yes	Yes	Yes	Yes	No	Yes
Parikh et al. [19]	Prospective study	No	Yes	Yes	Yes	Yes	No	Yes

^aThis item is labeled “No” if the spectrum of patients was representative of patients who received the test in practice, otherwise it is labeled “Yes”

^bThis item is labeled “No” when all patients received the same reference standard, otherwise it is labeled “Yes”

^cThis item is labeled “Yes” if patients who were lost to follow-up differed systematically from those who remained, otherwise it is labeled “No”

“—” This item is not applicable if the study was retrospective in design