Gray literature: An important resource in systematic reviews

Area of Science:

• Evidence-based practice
• Information science
• Research methodology

Background:

• Systematic reviews require comprehensive evidence identification.
• Gray literature offers valuable data often absent in commercial publications.
• Gray literature can mitigate publication bias and improve review timeliness.

Purpose of the Study:

• To highlight the benefits of incorporating gray literature into systematic reviews.
• To provide guidance on searching gray literature sources.
• To illustrate the contribution of gray literature to systematic reviews.

Main Methods:

• Narrative review of existing literature on gray literature.
• Discussion of benefits and challenges of gray literature searching.
• Presentation of an illustrative search example.

Main Results:

• Gray literature can include theses, dissertations, reports, and conference papers.
• Inclusion of gray literature reduces publication bias and enhances review comprehensiveness.
• Despite search challenges, gray literature benefits often outweigh costs.

Conclusions:

• Gray literature is essential for a balanced and complete picture of available evidence.
• A well-designed gray literature search strategy is invaluable for systematic reviews.
• Researchers should prioritize incorporating gray literature into their systematic review processes.