2.5. Data records and analysis

We will export all citations from the searched resources to the Endnote 7.0, and we will remove any duplicated studies. Two authors will independently review all titles and abstracts to check whether they meet the eligibility criteria for inclusion, and all irrelevant studies will be excluded. Then, full-text articles for studies that fulfill the review criteria will be obtained and judged. The reasons for all excluded studies will be noted. The whole process of study selection will be shown in a flowchart. Any discrepancies at either the initial or full-text screening between 2 authors will be solved or consulted by a third author through discussion when necessary.

Two authors will independently extract information from each selected study based on the previous designed sheet for data extraction. If there are any discrepancies between 2 authors, a third experienced author will be consulted to solve the different opinions. We will extract the following data: title, first author, publication time, location, patient characteristics, inclusion and exclusion criteria, study method, index test, refer test, outcomes, and funding information. If any insufficient information occurs, we will contact corresponding authors to inquire those data.