Ovid MEDLINE Search Instructions
Step Five - Combining Concepts
For complex search topics, it may be useful to conduct searches on two or more different subjects and then combine the results of these search sets. Sets can be combined using AND, OR, or NOT.
In the search box, type in the set numbers that you wish to combine using AND, OR, or NOT between the set numbers to indicate how you wish to combine them.
Then click "Perform Search."
Alternatively, you can click on the "combine" icon at the top of the screen; the database will then guide you through the process of combining sets.
Use and to retrieve only those articles in which all of the terms appear. For example, if you were interested in finding articles about the use of nicardipine to treat hypertension, then you would want to conduct two searches, one on hypertension, and one on nicardipine. You would use and to combine the search sets because you are interested in finding articles that mention both concepts, not articles that mention just one or the other.
Use or to retrieve articles in which any of the terms appear. For example, if you were interested in finding articles that were either about the use of nicardipine or the use of captopril for treating hypertension, then you would conduct a search on each drug, and then combine the sets using or. (The resulting set could then be combined with the set for hypertension using and.)
Use not to exclude a term or concept from your search. For example, if you were searching for articles on the use of nicardipine to treat hypertension, but wanted to exclude any articles that might also discuss the use of captopril, then you would combine the set on nicardipine and the set on captopril using not.
EXAMPLE - Combining search sets
To find articles about the use of nicardipine to treat hypertension, create two sets, one for each concept, then combine them with and. The resulting set will contain citations that mention both terms within the same article.