Help Available for Systematic Review Authors
Over the past year, HSLS has experienced an increase in requests for expert literature search assistance from authors writing systematic reviews (SRs). Cook et al define SRs as “overviews developed with the application of scientific strategies that limit bias to the systematic assembly, critical appraisal, and synthesis of all relevant studies on a specific topic”.1 SRs present concise, current, and rigorous synthesis of the best available evidence,2 and require comprehensive literature searches. SRs can present qualitative and/or quantitative information. SRs that statistically combine and summarize the results of several primary studies are called meta-analyses. The Cochrane Library, described in this issue, is noted for its rigorous and high quality systematic reviews.
Egger and Smith outline the steps involved in authoring a SR:3
1. Formulate review question
2. Define inclusion and exclusion criteria for research studies to be included in review
3. Locate research studies by using comprehensive search strategies
4. Determine which studies to include in review, based on criteria
5. Assess the quality of studies
6. Extract data from the studies
7. Analyze and present results
8. Interpret results by considering limitations, implications, etc.
The time commitment and challenges involved with such a project should not be underestimated. Although time spent on a SR can vary, it may take anywhere from nine months to three years to complete a review project. In a recent study, Sampson and McGowan identified SR search strategy errors such as missed spelling variants, truncation and logical operator error, missed Medical Subject Headings (MeSH), and incorrect use of MeSH.4 A librarian can help avoid these errors, by providing expert advice on locating studies for inclusion or by critiquing the search strategy used by a SR author.
Other challenges that should prompt prospective SR authors to seek a librarian’s assistance include:
• Determining scope and depth of bibliographic databases and trial registries
• Identifying publication and language bias
• Searching print literature in addition to databases
• Designing search strategies for electronic databases
o Translating the question to appropriate database-specific terminology
o Identifying text words and the appropriate controlled vocabulary to construct search statements
o Use of appropriate methodology filters (preferably validated)
o Construction of searches tailored to specific databases (MEDLINE, EMBASE, CINAHL, etc)
• Managing references with bibliographic management software such as Endnote or RefWorks
• Updating searches during the SR development process with saved searches and alerts
To contact a reference librarian for assistance with a systematic review, call the HSLS reference desk at 412-648-8796 or e-mail medlibq@pitt.edu to schedule a consultation.
1. Cook DJ, Sackett DL, Spitzer WO. Methodologic Guidelines for Systematic Reviews of Randomized Control Trials in Health Care from the Potsdam Consultation on Meta-Analysis. Journal of Clinical Epidemiology 1995; 48:167-171.
2. Cook DJ, Mulrow CD, Haynes RB. Systematic Reviews: Synthesis of Best Evidence for Clinical Decision. Annals of Internal Medicine 1997; 125(5): 376-380.
3. Egger M, Smith GD. Principles of and Procedures for Systematic Reviews. In: Egger M, Smith GD, Altman DG, eds. Systematic Reviews in Health Care: Meta-Analysis in Context, 2nd ed. London: BMJ Publishing Group, 2001:25.
4. Sampson M, McGowan J. Errors in search strategies were identified by type and frequency. Journal of Clinical Epidemiology 2006; 59:1057-1063.
--Ahlam Saleh
