A systematic review needs a systematic search strategy that attempts to identify all studies that meet the eligibility criteria. 

Step 1 - Formulate your question and translate it into a search strategy.

Step 2 - Identify the key concepts of your question. The frameworks used to develop your question are a good start.

This search strategy planner can also help you map out your key concepts and formulate your search.

Step 3 - Develop search terms based on your key concepts. The compose a search guide demonstrates how to compose a search and use it in some library databases. The guide covers the processes involved in composing a search using:                                                              

• Keyword searching
• Database syntax
• Subject heading searching
• Boolean logic

The following is a brief overview of search strategies from the compose a search guide that are most useful when conducting a systematic review.

See also Ross-White et al (2024) '2.4.3 Developing a Search Strategy' in the JBI Manual for Evidence Synthesis

Keyword searching is the most common form of searching. It involves searching for key words and phrases to identify papers that contain those words in the main fields (such as title and abstract).

As different authors may use different terminology, it is important to consider all relevant synonyms and alternate terms for your concept to ensure you are finding all relevant results on your topic.

In addition to searching a thesaurus for direct synonyms, think about:

• Medical vs common terms eg. Varicella Zoster vs Chicken pox
• Acronyms and abbreviations eg. COPD vs Chronic obstructive pulmonary disease
• Generic vs Brand names eg. Acetaminophen vs Panadol
• English vs American spelling eg. Tumour vs Tumor
• Broader vs narrower terms eg. Obesity surgery vs Bariatric surgery

Use Boolean to combine search terms

Use AND and OR to combine your keywords:

AND - use to combine keywords for different concepts e.g. diet AND exercise AND obesity
OR - use to combine keyword synonyms e.g. diet OR nutrition

Check if your chosen database has a Subject Heading relevant to each concept in your search.

Subject headings are like "tags", indicating the main topics of an article. Databases select the most relevant subject headings for each article from their controlled "thesaurus" of subject headings.

For systematic searching, it is important to search both keywords and subject headings, to ensure you have conducted a comprehensive search and identified as many relevant articles as possible.

If you only use keywords in your search strategy, you could miss articles if an author happened to use different words in their title and abstract.

If you only use subject headings in your search strategy, you could miss articles that have not been indexed or have older indexing.

Things to know about subject headings in databases:

• Not every database uses subject headings
• Each database may have their own subject headings that do not translate to other databases.
• Use the 'help' menu in a database to determine how to use subject headings in your search for a particular database.
• Read the "scope note" of a Subject Heading to see exactly how it is defined in that database, to determine if it is relevant to your question.

The advantage of using subject headings

• The same subject headings will be consistent across all papers in a database on the same topic
• Identifies the key concept regardless of the terminology used by the author
• Compiled into a searchable thesaurus

More details about how to find Subject Headings in the Compose a Search Guide.

For more information on why subject headings and keyword searches should be used together:

Solomons, T., & Hinton, E. (2021). Federated searches: why a one-stop shop approach to literature searching falls short for evidence synthesis. JBI Evidence Synthesis, 19(6), 1259-1262. https://doi.org/10.11124/JBIES-21-00177

When keyword searching you will often need to include punctuation symbols and search operators to help you find all the relevant papers. For example:

IMPORTANT: Always check the Help menu of the database you are using to check which symbols and operators can be used in that particular database.

More information about adding punctuation symbols to improve your search in the Compose a Search guide.

This webinar recording covers:

• Types of reviews & definition of systematic reviews
• Checking for prior reviews
• Search strategy planning, keywords and subject headings
• Where to search
• Boolean Operators AND & OR, Truncation & Wildcard searching
• Grey literature
• Managing search results in EndNote & Covidence
• PRISMA reporting standards