This section should detail how the reviewers will search for relevant papers. The documentation of search strategies is a key element of the scientific validity of a systematic review. It enables readers to look at and evaluate the steps taken and decisions made to consider the comprehensiveness and exhaustiveness of the search strategy for each included database. Initial keywords should be specified in the protocol along with the databases to be searched. A three-stage search strategy is recommended, including an initial search of the selected databases using the pre-specified keywords to identify additional relevant keywords and index terms, a second thorough search across all included databases, and then a final review of the reference lists of included studies in order to identify any studies that may have been missed. A completed search strategy for one database should be attached to the protocol as Appendix 1. If searching is restricted to a specific date range, then that should be specified in the protocol, as well as any language restrictions which may be applied. For further information on searching refer to the “Searching for studies of diagnostic test accuracy” section.