Systematic reviews

Searching databases

The first step in identifying studies is searching the most appropriate databases, which is dependent on your research question. You can find a list of databases here, but you should also consult with a librarian to ensure that you don't miss any pertinent databases. 

Here are some general guidelines to keep in mind when searching databases: 

  • Select databases in relation to the research question
  • Use previous reviews or consult our research guides
  • Study a database’s help pages
  • Increase your familiarity of search operators
  • Explore a list of subject terms or a thesaurus
  • Determine appropriate subject terms
  • Create personal accounts for saving searches in each database

Building your search strategy should include the following steps: 

  • Exploring the thesaurus
  • Understanding the types of terms and scope notes
  • Using the "explode" and "focus" functions appropriately (when available)
  • Exploiting the  search operators (AND, OR, NOT) as appropriate
  • Truncating with (*) or ($) or using wildcards such as (&) as appropriate
  • Using exact phrases "world war and combined concepts (war OR conflict)
  • Using the proximity and adjacency functions such as adj, w/, near as appropriate
  • Considering field searching such as title, abstract

Feel free to use a search strategy worksheet to start preparing your review. This worksheet helps identify the research question, relevant concepts along with useful synonyms.

In addition, you may want to consult the Library's search syntax translation guide to help you draft your strategy to take full advantage of the features available across different databases.

The Peer Review of Electronic Search Strategies (PRESS) provides a table with practical questions to enable self-review of a draft strategy (usually completed by a librarian). PRESS is an essential step that can help ensure:

  • Best databases have been identified
  • Best strategy has been developed (including search terms and search operators)
  • Appropriate limits have been applied

A template is also available to help you prepare the peer-review of a search strategy:

Supplemental searching with other resources

Once you have completed searching the databases, it is important to supplement your searching with studies that may not have been included in the databases. Here are some resources where you can locate supplementary materials for your systematic review:

Grey literature searching

The Fourth International Conference on Grey Literature defined grey literature as "that which is produced on all levels of government, academics, business and industry in print and electronic formats, but which is not controlled by commercial publishers." Here is a sample of resources you may want to consider when searching for grey literature:

  • OpenDOAR​ - Directory of academic repositories
  • - Database that searches for grey literature in the fields of medicine, specifically in health aging, disparities, history of medicine and prevention (note: resource is no longer updated as of January 2017)
  • Open Grey - Database that searches European documents on medicine, science, economics, social sciences and humanities.
Clinical trial registries

In addition, the United States Department of Health and Human Services has a complete list of clinical trial registries from around the world.


You can search for University of Ottawa dissertations and theses by following these instructions or you can search the University's repository, uO Research.

We also have access to more theses in the resources listed below:

Government and international databases

Using search filters

Search filters can be used to help narrow your search strategy by study design, population, or for specificity or sensitivity. 

The list above provides examples, but other filters and resources are also available.

Documenting the process

It is important to document your process as you create your systematic review to keep track of decisions made and to ensure that all the correct information is being included in your review. There are reporting standards that can be followed that can act as step-by-step guides.

Reporting Standards

The following lists provide examples of different reporting standards:

The EQUATOR Network (Enhancing the QUAlity and Transparency Of health Research) has created a comprehensive list of various Reporting Guidelines

On a more practical level, you can use a spreadsheet to keep track of the searching process and include the following information:

  • Databases searched
  • Dates when searching was done
  • Results per databases and duplicates removed
  • Detailed search strategies for each database with relevant notes

Here is an annotated example of an Excel spreadsheet used to help keep track of searching:

Using a citation manager

It is best to organize your references in a citation manager, so that they are easily accessible when you need them.

Citation managers allow you to:

  • Organize your references by database
  • Remove duplicate results
  • Manage the screening process
  • Download the full-text of included studies
  • Share your library with colleagues
  • Cite studies easily when writing your review in Word

The following citation management tools are suggested for systematic reviews:

Installation instructions, directions and additional information can be found on our citation management research guide.