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This tutorial will give you five tips for how to find clinical trials in PubMed.  Title Slide
The first step is to be able to recognize what a clinical trial looks like in a database. And also to know which types of publications are not clinical trials. Clinical trials are a type of primary study. This means they consist of new and original research that stands on its own. They are not a compilation or summary of other people's research.  In addition to content that duplicates audio, slide includes:
Defined in plain language: a clinical trial is an early test of a drug or treatment on a group of people to find out if it's both safe and effective.

You may have seen an evidence pyramid like this one. The higher levels of evidence-based research at the top build on earlier research. Some revised versions show a pyramid with wavy lines between categories to show that there is some overlap.

The primary studies are the original research. They are written and presented by those who did the research themselves. Randomized controlled trials here in blue are in this category. Also called RCTs, they are one type of clinical trial. RCTs are mentioned a lot because they are considered to be one of the best designed types of studies.

All of these types may be found in PubMed. They are searchable and often indexed with medical subject headings. The studies that look at other people's research that appraise other studies are in the top category. They're not usually considered to be original research.

You will likely come across many articles in PubMed that are in the purple category. Systematic reviews-- if your assignment requires you to update a systematic review, you will be looking for primary studies, not the top level secondary studies. You'll be looking especially for any new randomized controlled trials if they exist that have been published since the date of the systematic review. Therefore, skip articles in your search results that are reviews of others' work.

 Evidence Pyramid (see detailed view below).
They will be labeled as review article, systematic review, meta-analysis, or literature review. 

To find clinical trials and other primary studies in PubMed, skip articles that are reviews of other's work. 

Those articles may have these words in the title or description: review article, systematic review, meta-analysis, literature review.

These are filtered, secondary studies.
Tip number two, use filters to select for clinical trials as a publication type. After I run a search in PubMed as shown here, I will see the filters in the left hand column. Here, I've selected both clinical trial, which includes all phases of clinical trials and randomized controlled trial.  PubMed Search Results
Tip number three, use MeSH, Medical Subject Headings. Why use MeSH?  The MeSH tags allow you to find relevant articles more quickly.
Natural language searching or keyword searching looks for an exact match to what you type and it can bring up a lot of irrelevant results. MeSH terms allow you to search by concept and get superior results. Where do you find the MeSH search?  MeSH allow you to search by CONCEPT
Folic acid as keyword returns 51,128 results, including many irrelevant results. 
Folic Acid as MeSH term returns 37,847 results, with improved relevance. 
From the main PubMed search page, look to the lower right under Explore. Click on MeSH database.  PubMed Homepage. 
I'm going to type in folic acid then check the box on the left here in blue next to the item that best matches my desired topic. And on the right, I click on Add to search builder. Then I click on Search PubMed. This takes me back into the PubMed search.  MeSH search for Folic Acid.
To the top box, I've added an additional phrase, neural tube defects. And on the left, I use filters to limit to RCT and clinical trials, and I end up with 98 results.  PubMed search for "Folic Acid/theraputic use"[MeSH] and neural tube defects
Tip number four, use alternatives to MeSH when appropriate.  
Sometimes your topic doesn't have a matching MeSH term. And you'll see a message like this one.  Alert box: The following term was not found in MeSH: monjuvi. 
No items found. 
You can search synonyms such as the brand name and the generic name of a drug with or in between as shown here. PubMedSearch for: monjuvi or tafasitamab-cxix
Here are some other examples. Phrases that are synonyms or just similar topics, and how you could phrase the search with an or. Without the synonyms, you may miss some important research articles.  Pubmed Search bars including:
remdesivir or veklury
novel coronavirus or COVID 19
flu or influenza
You can add another component to the search by putting the phrase with "ors" in parentheses and then adding another word or phrase after it. But what if I can't find what I'm looking for?  PubMed search box with the search: (remdesivir or veklury) and infants
This brings us to tip number five. Be willing to try other search terms and keywords if you don't immediately find the results you were expecting. Here's an example.  
Previously, I was searching for the drug, monjuvi. It's a new drug and very little is published on it. After doing some background searching, I learned that it's a treatment for lymphoma and that it's a monoclonal antibody. So I go back to PubMed to see if I can find some clinical trials or other primary studies using the phrase, monoclonal antibodies. But instead of the y, I put an asterisk at the end of the root word. So it will pull up results for the word antibody or the word antibodies, plural. I can also check the MeSH database for matching MeSH term for monoclonal antibodies. PubMed search results for: monoclonal antibod*
  These tips will help you to get started finding clinical trials.
  1. Understand that a clinical trial is a form of original research, the results of which may be published in scholarly journals, and searchable within a database like PubMed. To find new and original research, avoid search results with these words in the title or description: review article, systematic review, meta-analysis, or literature review. 
  2. Use the filter to select for clinical trials as a publication type
  3. Use MeSH to find relevant articles more quickly.
  4. Use alternatives when appropriate.
  5. Be willing to try other search terms and keywords if you don't immediately find the results you were expecting. 
Here's a summary of the five tips for your reference. Most important, know the clinical trials are in PubMed and avoid articles with words like review article. Use a filter for clinical trials. Use MeSH and try alternatives when appropriate. A final note. If you're having trouble finding clinical trials, it's possible that they don't exist on that topic or that the trial is still in progress and hasn't yet been published. There may be other non-clinical trial primary studies on your topic. Or you may need to try a new strategy altogether such as broadening your search. Questions, contact your librarian.  
Librarians for Health Sciences and other areas can be found on the Ask a Librarian page.  Kathy Herrlich
Pharmacy Librarian
k.herrlich@northeastern.edu
  Closing Slide: Ask a Librarian library.northeastern.edu/ask

Evidence Pyramid

Evidence Level Design
Clinical Practice Guidelines Secondary, Pre-appraised or filtered study
Meta-Analysis, Systematic Review Secondary, Pre-appraised or filtered study
Randomized Controlled Trial

(prospective, tests treatment)

 Primary Study
Cohort Studies

(prospective - exposed cohort is observed for outcome)

 Primary, Observational Study
Case Control Studies

(Retrospective: subjects already of interest looking for risk factors)

 Primary, Observational Study
Case Report or Case Series, Narrative Reviews, Expert Opinions, Editorials No Design
Animal and Laboratory Studies No humans involved

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