In PubMed you can use Filters (sometimes referred to as Limits), located on the left hand side of the search results screen to limit your search by certain criteria. The Filters fall into several categories, such as Article Types, Article Language, etc. Some are visible on the search results screen by default, and some can be found and made visible for the future use when clicking Additional Filters button.

The Filters are efficient and handy tools for refining a search, adding desired criteria to your search terms, thus significantly increasing search precision.

However, users may not be aware of the fact that most of the Filters are, in fact, MeSH (Medical Subject Headings) terms set up as clickable Filters but functioning as MeSH terms behind the scenes. For example, if you apply a Clinical Trial Filter, your move will be translated by PubMed as adding a search term “clinical trial”[Publication Type] to your search strategy with an “AND” Boolean Operator, e.g. cancer AND “clinical trial”[Publication Type], Publication Type is a category in the MeSH tree.

Of course, if you are a proficient searcher you can type “clinical trial”[pt], instead of clicking the Filter button which just supports refining your search in an easy and visual way.

Filters are a great feature, however there is a caveat. When you apply a Filter that is a MeSH, your search will automatically be limited to Medline portion of Pubmed. Pubmed is comprised of Medline, as well as many open access articles (mostly coming from Pubmed Central) not indexed for Medline.

To efficiently search Pubmed in it’s entirety, you must construct your search strategy as a combination of MeSH and keywords. MeSH are assigned only to Medline references and there is some lag time in this process. When applying Filters that are based on MeSH to your search it will not retrieve these references only found outside of Medline, as well as some recent Medline references not yet assigned MeSH.

In other words, by using such Filters you limit your search results to Medline only (excluding some very recent references not yet assigned MeSH) instead of getting all Pubmed search results.

The Filter categories that are MeSH terms include:

• Article Type (publication type)
• Species
• Sex
• Age

These filters should be used with caution.

The non-MeSH Filters are safe to use in any search, including:

• Text Availability
• Associated Data
• Publication Date
• Article Language

In conclusion, it is possible to combine applying Filters with using appropriate search terms if you aim at limiting your search by some criteria, yet searching all of PubMed, but as this requires search proficiency it would be best to get assistance at your Library.

Systematic reviews (as well as other comprehensive evidence-based practice syntheses such as meta-analyses, scoping reviews, and living reviews) have in recent years become a buzzword in scientific publishing. However, many clinicians and researchers are unaware of the amount of time and effort these reviews require, and are not prepared for the process ahead.

The MSK Library’s Systematic Review Service provides resources and support for teams conducting comprehensive evidence-based reviews. One of the most important aspects of any comprehensive review is understanding, at minimum, what needs to be included. Thankfully, there are multiple tools and guidelines to assist you, including PRISMA.

What is PRISMA?

The PRISMA Flow Diagram

The PRISMA 2020 flow diagram shows the flow of information through the different phases of a systematic review. It outlines the number of records identified, included and excluded, and the reasons for exclusions.

PRISMA 2020 includes four different flow diagram templates based on the type of review and the sources used to identify studies:

• new systematic reviews, includes searches of only databases and registers
• updated systematic reviews, includes searches of only databases and registers
• new systematic reviews, includes searches of databases and registers, plus other sources
  
• updated systematic reviews, includes searches of databases and registers, plus other sources

PRISMA Extensions

Since 2015, a variety of extensions of the PRISMA Statement have been developed to facilitate the reporting of different types or aspects of systematic reviews, including:

• PRISMA for Abstracts
• PRISMA-ScR: Scoping Reviews
• PRISMA-P: Protocols
• PRISMA-DTA: Diagnostic Test Accuracy
• PRISMA-E: Equity
• PRISMA-IPD: Individual Patient Data
• PRISMA Harms (for reviews including Harm outcomes)
• PRISMA-S: Searching

Using PRISMA: Do This, Not That

PRISMA is a reporting guideline, not a how-to guideline. It is only designed to assist you in how to write up (aka report) the review process.

If you are reporting a systematic review, scoping review, meta-analysis, etc using PRISMA, you can describe it in your methods section like this:

• “this review is reported according to PRISMA”
• “we followed the PRISMA Statement to report this review”

These are examples of descriptions should NOT be used when writing up your review:

• “we conducted the search according to PRISMA”
• “the review conducted in accordance with PRISMA”

PRISMA-S: Reporting Literature Searches

The latest installment of PRISMA extensions is the PRISMA-S, an extension published in 2021, which is a 16-item checklist used to complement the PRISMA 2020 checklist and flow diagram, that focuses specifically on what needs to be included when reporting the literature search strategies for your review. Again, this is now a how-to, and your methods section should not describe your literature searches as conducted using PRISMA-S. Rather, it details what information should be included when writing up or reporting your review.

Some of the details that PRISMA-S recommends including in your write-up (either in the methods section or supplemental appendices) are:

• database name and platform (eg. MEDLINE database on the Ovid platform)
• full search strategies for every database and register included
• other sources or methods used to identify studies (hand searching, author contacts, grey literature, etc.)
• any limits, filters, or restrictions used or put into the searches
• dates of all searches and updates
• process and software used to manage citations, including removing duplicates (EndNote, Covidence, Distiller SR, etc.)

The Future of PRISMA

The following PRISMA extensions are in development in collaboration with the PRISMA group:

• Preferred Reporting Items for Systematic reviews and Meta-Analyses – for Children (PRISMA-C)
• Preferred Reporting Items for Systematic reviews and Meta-Analyses – Protocols for Children (PRISMA-PC)
• PRISMA guideline for systematic reviews of outcome measurement instruments, called PRISMA-COSMIN

A new installment in the ongoing project of modernizing ClinicalTrials.gov – the largest database of currently funded clinical studies in the world – will be made in June of this year.

The current ClinicalTrials.gov website will be replaced with the modernized one which will have a new look and feel and better functionality. The users will have a better way of searching, viewing, and downloading information about clinical trials.

The National Library of Medicine announcement includes information about registration for the information session about the coming change that will be offered on April 25 and provides a glimpse into more innovations that are in the pipeline.