Literature Searching and Reviews

Most common in healthcare, rapid reviews are a streamlined variation of the systematic review where individual steps are omitted or completed in a shorter time to accommodate decision makers (1, 2).

Differences between a systematic review and a rapid review (3-5)

As initially described, the recipients of the review will often be decision makers.

They should be involved in formulating the research question to ensure that the review answers the specific research question [4, 5]. Formulating the research question is an important element of a review, but recipients often formulate broad research questions. These broad research questions should be adjusted through dialog to achieve a more focused research question [3, 5]. The formulation of the focused research question can be done using conceptualization models. These models help to structure and define the research question. The most appropriate model to use depends on the topic. See Purpose and Scope. To limit the scope of a rapid review, the number of interventions, control groups and outcome measures can be limited (4).

It is recommended to develop a project protocol that describes the rationale, hypothesis and methods of the review (4, 5). Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) has developed a reporting guide for review protocols for systematic reviews, which can illustrate what should be reported in a protocol. The protocol can be registered in PROSPERO or Open Science Framework (OSF) Registries. See Protocol or Search Log. Review Protocol.

As initially described, a rapid review is usually prepared at the request of decision-makers in the healthcare sector. The review's inclusions and exclusions are formulated in collaboration with the recipients of the review. This is done to correctly focus the inclusion and exclusion criteria (4, 5).

See Literature Searching.

The systematic literature search in a rapid review can be limited to three topic-specific databases. Higgins et al. recommend Medline, Embase and Cochrane. If time resources are available, an additional 1 - 2 topic-specific databases can be added if time resources are available.

Searching for gray literature can be limited, but clinical trial registries or screening of references from systematic reviews can be included if relevant to the individual problem. The systematic literature search can be further limited by restricting the search to the language of publication (English, and if professionally relevant several languages) (4).

The sorting and selection process can be completed in less time by both reviewers screening at least 20% together and reaching consensus. Then one reviewer screens the remaining and the other reviewer reviews the list of excluded studies. At the full-text level, both reviewers screen the first 5-10 full-text articles together and reach consensus. Then one reviewer screens the remaining full-text articles and the other reviewer screens the list of excluded studies (4).

This approach has been found acceptable through a Delphi study (4), but Tricco et al. recommend that two individual reviewers screen and select studies to minimize selection bias (5).

The data extraction and quality assessment can be performed by one reviewer. However, it is recommended that a second reviewer verifies a proportion or all data extraction and quality assessment (4, 5). A validated quality assessment tool should be used for quality assessment. The scope of the review can be limited by quality assessing only those outcomes that are most important for decision-making (4).

Tricco et al. recommend including a general results section describing the included studies and their results, as well as a meta-analysis if relevant to the problem. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) can be used to assess the level of evidence for an individual outcome measure.l (see Data Extraction and Critical Assessment). Here, one reviewer can grade and another reviewer can verify the ratings (4).

1. Moher, D., L. Stewart, and P. Shekelle, All in the Family: systematic reviews, rapid reviews, scoping reviews, realist reviews, and more. Syst Rev, 2015. 4: p. 183.

2. Tricco, A.C., et al., A scoping review of rapid review methods. BMC Med, 2015. 13: p. 224.

3. Khangura, S., et al., Evidence summaries: the evolution of a rapid review approach. Systematic reviews, 2012. 1(1): p. 1-9.

4. Garritty, C., et al., Cochrane Rapid Reviews Methods Group offers evidence-informed guidance to conduct rapid reviews. J Clin Epidemiol, 2020. 130: p. 13-22. 

5. World Health Organization, Rapid Reviews to Strengthen Health Policy and Systems: A practical Guide, A.C. Tricco, E.V. Langlois, and S.E. Straus, Editors. 2017, WHO.

In addition to the literature referenced under References (above), read more in:

• Cochrane Rapid Review Methods Guidance:
  Garritty C, Hamel C, Trivella M, Gartlehner G, Nussbaumer-Streit B, Devane D, Kamel C, Griebler U, King V,

  Updated recommendations for the Cochrane rapid review methods guidance for rapid reviews of effectiveness. 
  BMJ 2024; 384 :e076335 doi:10.1136/bmj-2023-076335

• Bramer, W.M., et al., A systematic approach to searching: an efficient and complete method to develop literature searches. J Med Libr Assoc, 2018. 106(4): p. 531-541.
• Featherstone, R.M., et al., Advancing knowledge of rapid reviews: an analysis of results, conclusions and recommendations from published review articles examining rapid reviews. Syst Rev, 2015. 4: p. 50.
• Guyatt, G.H., et al., GRADE: an emerging consensus on rating quality of evidence and strength of recommendations. Bmj, 2008. 336(7650): p. 924-926.
• Higgins, J.P., et al., Cochrane handbook for systematic reviews of interventions. 2019: John Wiley & Sons.
• Moher, D., L. Stewart, and P. Shekelle, All in the Family: systematic reviews, rapid reviews, scoping reviews, realist reviews, and more. Syst Rev, 2015. 4: p. 183.