3. Overview
A review article or meta-analysis carefully gathers all
prior publications on a specific topic and summarizes
them to provide a big-picture analysis.
Steps:
1.An extensive search of the literature
2.Extraction of key information from relevant articles
3.Clear and concise presentation of this information
4. Benefits
• A literature review is an effective way to become an
expert in the literature on a well-defined topic
• A literature review is a helpful step in preparing for
future primary or secondary analyses
• Review articles are often cited more often than
reports of individual field studies
5. Limitations
• Not all journals publish review articles (especially
reviews that the editors do not solicit)
• Reviews are sometimes perceived to be a less
rigorous form of research than projects that collect
new data and/or involve statistical analysis
6. Selecting a Topic
• The most important decision is to select a topic that is
narrow enough that all the relevant publications can
be acquired.
• The topic may need to be modified after a preliminary
search, depending on the number of articles available.
– 8 = too few → expand the scope
– 352 = too many → narrow the scope
7. Library Access
• The full text of every relevant article must be
identified and obtained.
• Check with a university librarian about the library’s
policies and the fees that may be charged for the use
of interlibrary loan services.
• Maintain a meticulous system for tracking articles
that have already been acquired, those that have been
requested but not yet received, and those that need to
be requested.
8. Narrative Reviews
• Narrative reviews tell a “story” about a well-defined
topic using evidence from the literature to support the
“plot”
• Narrative reviews must be carefully organized by
theme, methodology, chronology, or some other
guiding principle
• The absence of a systematic search strategy must be
justified by the researcher
9. Systematic Reviews
• Systematic reviews are designed to minimize the bias
that might occur when review article authors
handpick the articles they want to highlight
• After the identification of the study question, the
most important decision in a systematic review is the
selection of keywords and inclusion criteria
• The goal is to craft a search strategy that identifies all
the articles ever published on the narrow, well-
defined area covered by the review
10. Systematic Reviews
• Once the articles are identified from one or more
abstract databases, each article is screened to see
whether it is eligible for inclusion.
• Relevant information is extracted from all eligible
articles and presented in table form.
• Then the trends and key observations are
summarized.
11. Meta-Analysis
• The goal of a meta-analysis is to combine the results
of several high-quality articles that used similar
methods to collect and analyze data into one
summary statistic.
• Meta-analysis usually begins with a comprehensive
systematic review of the literature to identify every
single possibly relevant article.
12. Meta-Analysis
• The inclusion criteria for a meta-analysis are usually
more restrictive than they are for systematic reviews.
• These restrictions are important because a summary
statistic is only meaningful when every study
included in the meta-analysis has very similar
definitions for exposures and outcomes, similar study
designs and methods, and similar populations.
• Trying to combine dissimilar studies could hide real
and meaningful differences among populations.
13. Meta-Analysis
The steps of a meta-analysis are to:
•Conduct a systematic review
•Assess the quality and comparability of each eligible
study
•Extract statistical results from each study that meets all
inclusion criteria
•Combine these statistical results into one summary
statistic
14. FIGURE 7-1 Key Characteristics of
Reviews and Meta-Analyses
