Identify your main concepts
You want to know:
Does the use of a mobile application improve medication adherence in older adults?
Next, craft the search using FOUR separate searches:
- Search 1 (S1): mobile application
- Search 2 (S2): medication adherence
- Search 3 (S3): older adults
- Search 4 (S4): Combines S1 AND S2 AND S3
Then, build your search one concept at a time and then use 'search history; to combine separate concepts. This allows you to test different combinations of the concepts to find the best set of articles for your needs, maybe (S1 AND S3) would give you a better set of results compared to (S2 AND S3).
Phrase Searching
Something to consider as you build your search is phrase searching. Phrase searching limits your results to articles containing an exact phrase, as opposed to keywords scattered throughout the title, abstract, author, or journal fields. Adding double quotes around a set of words will turn them into a phrase.
1. Your search (not a phrase): patient compliance (~133,491 results)
Article title: Regulatory landscape with U.S. patient requirements and Clinical Trial Diversity expectations
Author: Melissa Vozza (CDCS Regulatory Compliance & Quality Assurance, Fortrea, USA.)
- This search using the keywords patient compliance could return an article that contains the word patient in the title and an author that is affiliated with a compliance office. This could be a relevant result, but it’s important to understand how the database uses your keywords in the search.
2. Your search (a phrase): "patient compliance" (~71,277 results)
Article title: Patient Compliance With Bowel Preparation for Elective Colorectal Surgery
- Putting quotes around your keywords will return results that only use the whole intact phrase. However, you need to be thoughtful when searching for phrases because there could be many relevant variations on a phrase that won't appear in results because they appear in a slightly different order. For example, a search for "breast cancer" may miss articles that use the terms "cancer of the breast" or "cancerous breast tissue."
Synonyms
The next step is to add synonyms for each concept, using phrase searching when appropriate. Synonyms are important because a relevant article might use different words than your original concept terms. Think back to our question from the first step:
Does the use of a mobile application improve medication adherence in older adults?
If you search in PubMed for "mobile application" AND "medication adherence" AND "older adults" [click to run the search] you will get relevant results, but there are likely many more relevant articles that use slightly different words for each concept. To find those additional results, you will need to include synonyms. For example:
- "mobile application," smartphone, "mango health," dosecast, medisafe
- "medication adherence," "drug adherence," "drug compliance," "patient compliance"
- "older adult," "older adults," elder, elderly, senior, geriatric, gerontology
Boolean
Boolean operators such as AND and OR are used to connect synonyms and concepts. Imagine that all of the colored dots or dot clusters below represent articles about different topics. To get the database to return only relevant results, you will use different combinations of our relevant keywords and ANDs and ORs.
- Use OR to combine synonyms to expand your search for a concept. Your search results will contain citations for each term. Place parentheses around the search terms when you use OR so that the database searches them together.
- ("mobile application" OR smartphone)
- Use AND to connect concepts. This will narrow your search results, giving you just the articles that include all terms, that is, the intersection of the search terms you've used.
- ("mobile application" OR smartphone) AND ("medication adherence" OR "drug adherence")
- Always capitalize boolean operators; if you don't, they'll be ignored in some databases.
For example:
- Search 1: "mobile application" OR smartphone OR "mango health" OR dosecast OR medisafe
- Search 2: "medication adherence" OR "drug adherence" OR "drug compliance" OR "patient compliance"
- Search 3: "older adult" OR "older adults" OR elder OR elderly OR senior OR geriatric OR gerontology
- Search 4: S1 AND S2 AND S3 [click to run the search - notice how many more results this version of the search returns]
Controlled Vocabulary
Controlled vocabulary is a standardized set of terms used by databases to describe and categorize articles based on their content. It works similarly to a unique hashtag for social media posts (e.g. #APHA2024 for the American Public Health Association 2024 meeting) or navigating through an online store's categories to get to a desired item (Clothing > Women's Clothing > Tops > Sweaters) rather than using the search box.
Using controlled vocabulary terms can return more relevant and specific results, and can help overcome variance in terminology, but you have to know where to find it and how to add it to your search. Different databases have their own controlled vocabularies:
- MEDLINE / PubMed - Medical Subject Headings (MeSH)
- CINAHL - CINAHL Subject Headings
- Embase - Emtree
Not all databases use controlled vocabulary; for example, Google Scholar and Scopus do not have their own controlled vocabulary. Searching with only controlled vocabulary may limit your results to just the articles that have been indexed - you may miss new articles or articles that are older than the controlled vocabulary term.
Here is a sample search in PubMed using just a few relevant MeSH terms for our research question:
Does the use of a mobile application improve medication adherence in older adults?
Pulling it all together!
The search process is iterative! After running an initial search and skimming through the results, you may discover new keywords to include or see that one of your keywords is pulling in irrelevant results. You may also realize that you need to break out an additional concept from your research question or find that your concepts need to be combined in a different way.
It is helpful to keep track of all of the search terms that you have used during your search process in order to create the most comprehensive search and to allow the search to be run again at a later time. If you plan to publish the results of your literature review, you may also need to include a section on your search methodology.
Choosing the "right" search for the job depends on how comprehensive the search needs to be and how much time you have to review results. Here are a few sample iterations for our research question [click on the links to view search results]:
1. "Mobile Applications"[MeSH] AND "Medication Adherence"[MeSH] AND "Aged"[MeSH]
- This version of the search is the most narrow and specific.
- This version of the search is slightly more sensitive and will pull in more results than in search #1.
- This version of the search is the most sensitive of the 3. Combining keywords with controlled vocabulary will return results that were likely missing from searches #1 and #2, but the tradeoff is possibly seeing more irrelevant results.
- This example uses [tiab], which is a field tag that tells Pubmed to search for that keyword only in specific fields, title or abstract. This can help focus the search to more relevant articles because it won't return results where the keywords appear in less relevant fields, like author name and affiliation, or the name of the journal. To learn more about PubMed's field tags, please visit their Help page.