Table 5 Detailed assessment of quality of studies and risk bias with QUADAS-2

Patient Selection

If the study explained that the USGFNAB and PGFNAB samples were taken sequentially or randomly, the control study design was avoided, and that unnecessary exclusion was avoided, it was given a positive (+) sign or low bias.

If the sample entered falls under the research question, the applicability is given a positive sign (+).

Index Test

If the study explained that the PGFNAB and USGFNAB tests were performed without knowing the histopathological results and that the threshold had been determined previously, it was given a positive sign (+) or low bias.

If the index test is performed and the interpretation falls under the research questions, the applicability is given a positive sign (+).

Reference Standard

If the study explains the gold standard according to the standard and researchers interpret it without first knowing the index test results, they are given a positive sign (+) or low bias.

If the study does not explain the type of gold standard or if the researcher interprets the gold standard without first knowing the index test results, the study is unclear.

If the target conditions are being studied, the applicability is given a positive sign (+).

Flow and Timing

When describing the PGFNAB/USGFNAB interval with operative histopathology, the study was given a positive (+) sign or low bias, all patients were given the gold standard, and all patients were included in the analysis. Not all of the patients in Goudy’s study were included in the analysis.