Database Search Tips

The first step to a successful literature search is to state your research question as clearly as possible.

It is important to:

• be as specific as possible
• not include multiple questions into one question or search
• identify all important aspects of your question (though you may not be including all in your search!)

Clinical and social science questions can often be broken down into these aspects (PICO):

• People/population/problem  (What are the characteristics of the population?  What is the condition or disease?)
• Intervention (What do you want to do with this patient?  i.e. treat, diagnose)
• Comparisons [not always included]  (What is the alternative to this intervention?  i.e. placebo, different drug, surgery)
• Outcomes  (What are the relevant outcomes?  i.e. morbidity, death, complications)

If the PICO model does not fit your question, try to use other ways to help you pull out the most important aspects of your question. Perhaps asking yourself Who, What, Why, and How will help. The goal is to make sure you identify the aspects that you would expect to find in each article your search retrieves.

Example:  Do elderly patients who have suffered a heart attack, also known as myocardial infarction (MI), experience higher rates of depression?

Key concepts:  Do elderly patients who have suffered a heart attack experience higher rates of depression?

It would be a clinical question (and better fit the PICO model) if you were interested research the treatment of depression in post-heart attack, elderly adults. So if your question was:

Example: Does cognitive behavioral therapy improve depression in post-MI elderly patients compared to placebo?

Your PICO might look like (with key concepts highlighted):

• Population: post-heart attack elderly patients experiencing depression
• Intervention: cognitive behavioral therapy
• Comparison: none or placebo
• Outcome: reduce or improve depression

It's best to use Boolean Operators and parentheses to tell the database how to handle your search terms. The parentheses keep synonyms or similar concepts together using OR while the AND links those concepts together. (Most databases will automatically include an AND if you do not between concepts but it doesn't always parse your concepts correctly.

To be sure the database searches the way you want, use Boolean Operators and parentheses!

So using the examples above your search would be:

(heart attack OR myocardial infarction) AND depression

Searching is an iterative process. Your goal should be to find all of the articles that are pertinent to your subject not just "a few good ones". Successful searching requires you to think about the complexity of language. You need to match the words you use in your search to the words used by article authors and database indexers. A thorough search must identify the author words likely to be in the title and abstract and the controlled vocabulary terms, if appropriate (i.e. MeSH, CINAHL Headings, Emtree, etc).

Step #1: Initial Search

Start by doing a preliminary search using the words from the key parts of your research question. Enter the key concepts from your research question combined with the Boolean operator AND.

 heart attack AND elderly AND depression 

The search retrieves a large number of relevant article records, but probably not everything on the topic.

Step #2: Evaluate Results

Review the results to examine the words used in the articles that are directly related to your topic.

• look for words in the titles and abstracts of these pertinent articles that differ from the words you used
• look for relevant index terms in the list linked to each article (i.e. if you are using a database like PubMed, Embase, or CINAHL)

Here are word differences to consider:

• Initial search used heart attack. Consider the plural form. Controlled vocabulary, such as PubMed's MeSH, would use Myocardial Infarction.
• Initial search used elderly.  Relevant controlled vocabulary term from MeSH is Aged
• Initial search used depression. Relevant controlled vocabulary terms from MeSH are Depression and Depressive Disorder

With this knowledge you can reformulate your search to expand your retrieval by adding the words above and/or other synonyms. Databases that have a controlled vocabulary can help ensure you catch all the relevant literature on a specific topic.

#3 Revise Search

Use the Boolean OR operator to group synonyms together and use parentheses around the OR groups so they will be searched properly.

Here is what the new search looks like:

(heart attack OR myocardial infarction) AND (elderly OR aged) AND (depression OR depressive disorder)