The TARCiS statement comprises ten evidence-based recommendations and four research priorities. It provides guidance for systematic reviewers on when and how to conduct citation searching and on how to report it.
TARCiS is intended to be used by researchers, systematic reviewers, information specialists, librarians, editors, peer reviewers, and others who are conducting or assessing citation searching methods.
The TARCiS statement was published in 2024.
For background on evidence retrieval, Delphi procedure, and study group composition, please refer to this publication.
The following terminology should be used to describe search methods that exploit citation relationships:
For "difficult-to-search-for" systematic search topics, backward and forward citation searching should be seriously considered as supplementary search techniques.
For "easier-to-search-for" systematic search topics addressed by a highly sensitive search, backward and forward citation searching are not explicitly recommended as supplementary search techniques. Reference list checking of included records can be used to confirm the sensitivity of the search strategy.
Backward and forward citation searching as supplementary search techniques should be based on all included records of the primary search, i.e., all records that meet the inclusion criteria of the review after full-text screening of the primary search results. Occasionally, it can be justified to deviate from this recommendation and either use further pertinent records as additional seed references or only a defined sample of the included records.
Backward citation searching should ideally be conducted by screening the titles and abstracts of the references cited by the seed references as provided by a citation index. Screening titles as provided when checking reference lists of the seed references can still be performed.
Using the combined coverage of two citation indexes for citation searching to achieve more extensive coverage should be considered if access is available. This combination is especially meaningful if seed references cannot be found in one index and reference lists were not checked.
Before screening, the results of supplementary backward and forward citation searching should be deduplicated.
If citation searching finds additional eligible records, another iteration of citation searching should be considered using these records as new seed references.
Stand-alone citation searching should not be used for literature searches that aim at completeness of recall.
Reporting of citation searching should clearly state
The effectiveness, applicability, and conduct of indirect citation searching methods as supplementary search methods in systematic reviewing require further research (including retrieval of additional unique references, their relevance for the review and prioritization of results).
Further research is needed to assess the value of citation searching. Potential research topics could be:
Further research is needed to assess the best way to perform citation searching. Potential research topics could be:
Further research is needed to reproduce existing studies: Any recommendations in this Delphi that are based on only 1-2 studies require reproduction of these studies in the form of larger, prospectively planned studies that grade the evidence for each recommendation and propose additional research where the grade of evidence is weak.
As of November 2023