Per IOM Standard 3.1, below are elements required to conduct a comprehensive systematic search for evidence:
3.1.1 Work with a librarian or other information specialist trained in performing systematic reviews to plan the search strategy
3.1.2 Design the search strategy to address each key research question
3.1.3 Use an independent librarian or other information specialist to peer review the search strategy
3.1.4 Search bibliographic databases
3.1.5 Search citation indexes
3.1.6 Search literature cited by eligible studies
3.1.7 Update the search at intervals appropriate to the pace of generation of new information for the research question being addressed
3.1.8 Search subject-specific databases if other databases are unlikely to provide all relevant evidence
3.1.9 Search regional bibliographic databases if other databases are unlikely to provide all relevant evidence
The figure above shows "levels if evidence analyzed in a systematic review."
Kruse CS
Writing a Systematic Review for Publication in a Health-Related Degree Program
JMIR Res Protoc 2019;8(10):e15490
URL: https://www.researchprotocols.org/2019/10/e15490
DOI: 10.2196/15490
PMID: 31527018
PMCID: 6914304