How to conduct a systematic search

To conduct a systematic search, a combination of subject headings and keywords are used to retrieve as much available evidence as possible.

• Keywords: Keyword searching looks for words and phrases found in the database record; e.g. the titles and abstracts.
• Subject headings: Subject headings are human-curated terms assigned to the articles database record, which are organised into a hierarchical index of categories.

For example, if you are researching heart attacks, an author might use the term ‘heart attack’, but the subject heading might be 'Myocardial infarction'.

So, when you search using the subject heading 'Myocardial infarction', you'll find all articles that have had that subject heading assigned – even ones where authors only refer to the condition as 'heart attack’.

Please note that very new articles may not have been indexed with subject headings yet and as subject headings are assigned, human curation may be imperfect. Including both subject headings and keywords helps ensure a sensitive, comprehensive search.

As you identify subject headings and retrieve results, you may pick up alternative synonyms. Don't forget to add these to your concept map. Searching is an iterative process and takes a considerable amount of time.

Drag the control across or select the dots to learn more.

Researchers typically search Medline first in health systematic searching because it offers a comprehensive, up-to-date collection of high-quality primary research articles that are essential for building an evidence-based synthesis. Medline is trusted for its advanced search tools, controlled vocabulary (MeSH), and focus on peer-reviewed content.

This video [11.53 min.] demonstrates the systematic search process in the Medline database.

Don't forget to document and save your search. Subject headings vary between databases so make sure you record what subject headings you have used in each one.

Be aware of any guidelines that are required, e.g. PRISMA. Refer to the 'Document your search' section in this guide.