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A Guide to Systematic Reviews and Evidence Synthesis Service @ ULS

This guide will define types of evidence synthesis reviews and how the library can help.

STEP 1. Identify your research question

A well defined research question should address a gap in the current literature and is the essential starting point of your synthesis.

You can use the following frameworks to help construct your research question.


PICO for Quantitative Studies
I        Intervention/Exposure
C       Comparison
O      Outcome
Example: Is gabapentin (intervention), compared to placebo (comparison), effective in decreasing pain symptoms (outcome) in middle aged male amputees suffering phantom limb pain (population)?


PICo for Qualitative Studies
I        Phenomenon of Interest 
Co    Context
Example: What are the experiences (phenomenon of interest) of caregivers providing home based care to patients with Alzheimer's disease (population) in Australia (context)?


P   Perspective (for whom)
I    Intervention/Exposure
C   Comparison
E   Evaluation
Example: What are the benefits (evaluation) of a doula (intervention) for low income mothers (perspective) in the developed world (setting) compared to no support (comparison)?


PI   Phenomenon of Interest
D    Design
E     Evaluation
R    Study Type
Example: What are the experiences (evaluation) of women (sample) undergoing IVF treatment (phenomenon of interest) as assessed?

Design:  questionnaire or survey or interview

Study Type: qualitative or mixed method


The above was adapted from Cornell University A Guide to Evidence Synthesis: 1. Develop a Research Question


STEP 2. Define inclusion and exclusion criteria

After finalizing your research question but before you start your search, you need to define your inclusion and exclusion criteria.  You must decide what contents an article MUST have before being included in the review.  You also must determine which attributes would exclude an article from the review.  


Common Inclusion/ Exclusion pictorial representation

Image from the University of Melbourne Libguide Systematic Reviews


STEP 3. Write a search strategy

Your search strategy must be exhaustive, encompasses multiple databases, include grey literature and be reproducible.  PRISMA guidelines state that the full search strategy for at least one major database should be reported in an appendix and published along with the review (

The University Library System provides access to a wide range of databases which can be accessed by subject on the A-Z database list. Most databases have controlled vocabulary (a certain way words and phrases are indexed) which is unique to the database. This may require using different terms for different databases."Given the complexity of the many indexing languages and rules governing the various databases, we recommend that early in the process you make use of an experienced research librarian who can examine your search strategy and help you choose citation databases relevant to your review question." (Aromataris, Edoardo PhD; Riitano, Dagmara BHSC, BA Systematic Reviews: Constructing a Search Strategy and Searching for Evidence, AJN, American Journal of Nursing: May 2014 - Volume 114 - Issue 5 - p 49-56 doi: 10.1097/01.NAJ.0000446779.99522.f6)

Grey literature is produced outside of traditional publishing and distribution norms.   This can included, among other things, white papers, government publications, working papers, preprints, unpublished trial data, and conference proceedings and abstracts. Grey literature can be found in some citation databases, as well as databases dedicated to grey literature.

Some databases dedicated to grey literature include:


Some sources for preprints include:


An example of a complete and reproducible search strategy can be found in Appendix 1 of Petriwskyj, P. (2013). Family involvement in decision making for people with dementia in residential aged care: a systematic review of quantitative and qualitative evidenceJBI Database of Systematic Reviews and Implementation Reports11(7), 131–282.


STEP 4. Register Protocol

A protocol  lists the objectives, methods, and outcomes of primary interest of the systematic review.  Protocols promote transparency of methods and allows your peers to review how you will extract information to summarize the data. Registration of your protocol establishes your intent to conduct this review which may reduce the risk of others conducting similar reviews.

Here is an example of a published protocol 

Mengesha, M.M., Ajema, D., Teshome, A. et al. The association between diagnosis disclosure and adherence to antiretroviral therapy among adolescents living with HIV in sub-Saharan Africa: a protocol for systematic review and meta-analysis. Syst Rev 9, 160 (2020).


Protocol Reporting Guidelines and Checklists


Protocol Templates


Protocol Registries

STEP 5. Manage Search Results

It is important to keep track of all search results from each database.  The use of a template is recommended to capture the following information:

  • Database Name
  • Date Searched
  • Keywords and Combination of Terms
  • Search History
  • Limiters (Language, Time Period, Publication Type)
  • Number of Results
  • Number of Duplicates


After running the search through a database, export the results to a citation manager. The method of export will depend on the database and the citation management tool used.  Once all results from all sources are uploaded into a citation manager, you will need to de-duplicate the result list.

Visit our Library Guide, "Introduction to Citation Management" for an introduction to citation management tools and links to upcoming citation management workshops workshops.


STEP 6. Select Studies Based on Inclusion and Exclusion Criteria

Start with the screening of title and abstract to determine if a reference is relevant to your review.  Obtain the full text of a reference if further screening is necessary.  At least two reviewers will be needed to make a final determination on inclusion.


MECIR Box 4.6.c Relevant expectations for conduct of intervention reviews, Cochran Handbook 

Mandatory IInclusion Data


There are systematic review tools available to help with the screening process:


Free Tools


Tools which have a subscription cost


More tools for conducting systematic reviews can be found at the SR Toolbox

STEP 7. Extract data from included studies

The reviewers must read the full text of the articles which were selected for inclusion in the review.  The pertinent data must be extracted from each article.  A standardized data extraction form should be used. An example of a data extraction form can be found below.

If your review will contain a meta-analysis you may want to code the data in order to automate the statistical analysis process.  Some systematic review software packages listed in step 6. can help you create coded data instruction forms. Instructions on designing a coded data extraction form can be found in the following article:

STEP 7. Assess quality of evidence in included studies

It is necessary to evaluate each study included in your review for bias.  Cochran defines bias as "a systematic error, or deviation from the truth, in results or inferences. Biases can operate in either direction: different biases can lead to underestimation or overestimation of the true intervention effect". (Cochran Handbook 8.2.1)

Bias is evaluated on a level of risk.  The risk of bias (RoB) can be demonstrated using a variety of tools:

More information and an analysis of RoB tools can be found in the article:

Ma, L. L., Wang, Y. Y., Yang, Z. H., Huang, D., Weng, H., & Zeng, X. T. (2020). Methodological quality (risk of bias) assessment tools for primary and secondary medical studies: what are they and which is better?. Military Medical Research7(1), 7.

Some study quality assessment tools include

STEP 8. Present results

PRISMA provides a list of items to consider when reporting results. 

  • Study selection:  Give numbers of studies screened, assessed for eligibility, & included in the review, with reasons for exclusions at each stage, ideally with a flow diagram.
  • Study characteristics:  For each study, present characteristics for which data were extracted (e.g., study size, PICOs, follow-up period) & provide the citations.
  • Risk of bias within studies:  Present data on risk of bias of each study &, if available, any outcome level assessment.
  • Results of individual studies:  For all outcomes considered (benefits or harms), present, for each study: (a) simple summary data for each intervention group  (b) effect estimates & confidence intervals, ideally with a forest plot. 
  • Synthesis of results:  Present results of each meta-analysis done, including confidence intervals & measures of consistency.
  • Risk of bias across studies:  Present results of any assessment of risk of bias across studies.
  • Additional analysis:  Give results of additional analyses, if done (e.g., sensitivity or subgroup analyses, meta-regression).

Preferred reporting items for systematic review and meta-analysis protocols (PRISMA-P) 2015 statement


PRISMA Diagram Generators


Other Reporting Templates



Information in this section reproduced under a Creative Commons Attribution 4.0 license from the University of Michigan Libguide, "Systematic Reviews"