Searches in databases result in citations and abstracts. Most systematic review preparation information suggest that authors begin by appraising abstracts only, not the full text of the item, as it can be time-consuming and costly to obtain the full text of every item retrieved in a search.
All reviewers should have access to the inclusion and exclusion criteria created earlier in the process.
Remove duplicate abstracts from your search results. You may find the same citation in two or more databases.
Each abstract should be reviewed by at least 2 reviewers, independently.
If an abstract meets the inclusion criteria, mark it as INCLUDED. If it does not meet the criteria, mark it as EXCLUDED. If you are not sure, mark it as MAYBE.
Not all abstracts contain all the needed information to make a decision. If you cannot determine if the abstract meets the criteria, mark it as MAYBE.
Any citations that do not include an abstract should be marked as MAYBE.
After each abstract has been reviewed by 2 people, the whole group of authors should examine the reviewers' marks.
After appraising abstracts, your team will have a set of abstracts they wish to include in the review and a set of citations without abstracts which may be included in the review. You must obtain the full items for all these citations.
Two authors should independently read each item to determine if they meet the inclusion/exclusion criteria. The reviewer opinions should be examined by the entire team, and disagreements in inclusion/exclusion should be discussed by the entire team. You can use similar processes as you did for examining abstracts to record the reviewers' opinions of the full-text items. All co-authors need to have access to the full text of each item.
In addition to using the inclusion/exclusion criteria previously established, you can examine the quality of studies and data analyses.
The following list provides worksheets for critical appraisal of different study types:
After you have completed this step, you will have identified all the acceptable articles and other items that meet your criteria. These items should now be moved onto the next step, data extraction and synthesis.
In the process of conducting your review, you will build a large collection of original research articles that you will need to keep organized and eventually cite in your completed project.
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PRISMA is an evidence-based minimum set of items for reporting in systematic reviews and meta-analyses. PRISMA primarily focuses on the reporting of reviews evaluating the effects of interventions, but can also be used as a basis for reporting systematic reviews with other objectives (e.g. evaluating aetiology, prevalence, diagnosis or prognosis).
Reporting Standards
There are a number of reporting standards for systematic reviews. These can serve as guidelines for protocol and manuscript preparation and journals may require that these standards are followed for systematic reviews.
Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) is an evidence-based minimum set of items for reporting in systematic reviews and meta-analyses.
An updated version of the original PRISMA standards for protocol development.
Extension of the original PRISMA standards for systematic reviews and meta-analyses of individual participant data.
The EQUATOR (Enhancing the Quality and Transparency Of health Research) Network is an international initiative that seeks to improve the reliability and value of published health research literature by promoting transparent and accurate reporting and wider use of robust reporting guidelines. They provide a list of various standards for reporting in systematic reviews.
PRISMA Flow Diagram
The PRISMA flow diagram depicts the flow of information through the different phases of a systematic review. It maps out the number of records identified, included and excluded, and the reasons for exclusions. Most systematic reviews include a PRISMA flow diagram to track the search, screening and selection process. See below for resources to help you generate your own PRISMA flow diagram.