When searching in PubMed for a systematic review, sometimes you can use a basic search string that you learned to develop in the Creating a Basic Keyword Search String for a Systematic Review tutorial. However, you should also consider searching with a combination of keywords and subject headings in databases that use subject headings.
In this tutorial, I will show you how to combine keyword and Medical Subject Heading (MeSH) search in PubMed using the "Lego method" of searching.
What does "Lego method" mean? When searching in PubMed, start by searching all of your keywords and MeSH terms individually (like grabbing your favorite Lego pieces). Once you have all of your pieces in front of you, you can "build" them all together with Boolean operators.
1. Search your keywords in the PubMed search box one at a time. Include any phrase searching or truncation symbols as necessary. These types of searches are described in Brainstorming Keywords and Subject Headings tutorial.
2. Once you have searched all of your keywords, it's time to search for the MeSH terms for those words. You can search for MeSH terms by selecting MeSH in the dropdown box on the main PubMed page and searching a term. In the below example, I searched for the MeSH term for chronic obstructive pulmonary disorder. This search retrieved: Pulmonary Disease, Chronic Obstructive.
Below the term, I can choose as many relevant subheadings as I want in order to further focus my search. If you do not choose any subheadings, PubMed will include all of them. When you are ready, select Add to search builder on the top right, and then select Search PubMed.
3. Continue to search for all of your keywords separately until you have none remaining.
4. Also continue to search for MeSH terms separately. If you find multiple relevant MeSH terms, you can select the check box on the left of all of those terms. Then, change the Boolean AND in the dropdown box on the right to OR, select Add to search builder, and then select Search PubMed. This produces the same result as if you were to search the MeSH terms separately.
5. After you have completed searching for all of your keywords and MeSH terms, select Advanced underneath the PubMed search box. The next page will show your entire search history. From the list of searches, select Add next to all synonymous keywords and MeSH terms. This will throw all of your terms to the search boxes above the search history. Make sure to change all of the AND operators in the dropdown box to OR and then search. Repeat this step for all concepts.
6. After you have linked synonymous keywords and MeSH terms with OR, you are ready to move to the next step! Go back to the Advanced page. Now, select Add by the term groupings that you created in step 5. Leave the Boolean AND in the dropdown box and search.
You can download your search history or save the entire search string in the PubMed search box to document your search strategy.