Focused Searches by Topic: Populations

Background

The terms for indigenous populations in New Zealand and across the Pacific has recently changed. So from 2024 we have a more easily recognizable set of MeSH terms. The term “Maori People” is a new term beginning this year. The old term “Oceanic Ancestry group” (a broader term) was replaced this year by Oceanians – including Australiasian People, Pacific Island People, and other pacific islander peoples. Because this is a new term, keyword-type searches are required to capture records before 2023. Where necessary geographic location is used to narrow results.

Strategy

"Maori People"/

(Maori or pacifica or first nation? or first peop* or indigen*).mp.  

exp "Native Hawaiian or Other Pacific Islander"/

(nz or new zealand*).in. or new zealand*.ti,ab,sh. or "north island".ti,ab. or "north island".in. or south island.ti,ab. or south island.in.

(1 or 2 or 3) and 4

Focused Searches by Topic: Populations

Background

The words and phrases that we use to describe sexuality and gender have blossomed over recent years. This might be due to changes in societal attitudes or in the changing status of people who are part of these groups. Broad categories in MeSH include “Sexual and gender minorities” that has grown and changed in 2018 – view the history to see how the list has changed. Sexuality has not changed as much, but terms associated with changing gender, or gender identity may have. These terms may be used when seeking out information about healthcare for minority groups.

Strategy

sexuality/ or bisexuality/ or heterosexuality/ or homosexuality/ or homosexuality, female/ or homosexuality, male/ [Sexuality terms]

(lesbian? or gay? or bisexual* or queer or lgbtq*).mp. [Sexuality keyword terms]         

1 or 2

"sexual and gender minorities"/ or gender-nonconforming persons/ or intersex persons/ or transgender persons/ or sexual behaviors/

gender identity/ or femininity/ or masculinity/ or transsexualism/

(cisgender? or transgender or gender affirm* or gender identit* or gender nonconform* or gender fluid*).mp.

4 or 5 or 6

Transvestism/

Gender Dysphoria/ [From 2016]

sex reassignment procedures/ or puberty suppression/ or sex reassignment surgery/ [From 2011]

"sexual and gender disorders"/

Health Services for Transgender Persons/ [from 2013]

or/1-12

exp health inequities/ or socioeconomic disparities in health/

13 and 14

How to use the database command 'docz.dz.' and the Status (ST) field to identify the constituent parts of Ovid MEDLINE and show their relative sizes.

Background

This Focused Search establishes the number of records in the Ovid MEDLINE database as well as the status of those records at the time of the executed query. Database records enter the database via different routes. They move through a series of editorial processes and quality control checks and are only accorded MEDLINE status upon completion of those checks.

A record with MEDLINE status will have had MEDLINE’s proprietary medical subject heading terms, the so-called “MeSH terms” allocated to it. Knowing this has important consequences for how you build a search. Some 14% of the records in the database do not have MEDLINE status and so will not be captured using a search that only relies on MeSH thesaurus terms. Also, some limits, for example the Publication Type, Randomized Controlled Trial (randomized controlled trial.pt.) or Age Groups, All Adult (19 plus years) only operate on MEDLINE status records.

Noteworthy here is that the Status (ST) field, deployed as a limit, makes no mention of books. Books as a type of database record is accounted for by #7 in the search strategy, so that the number of records produced by lines #1 and #8 are the same. See below the attached reference Ovid's Medline Compared To PubMed (Ovid Knowledge Base) for details.  

The docz.dz Command
Entered at the command line in any of Ovid MEDLINE’s search modes, you can use the docz.dz command on any database on Ovid to establish the number of records in the resource. By combining this database command with database fields such as Status (ST) or Publication Type (PT), either individually or in combination, it becomes possible to imagine the ‘shape’ of the database. By this is meant the database’s structure, its composition in terms of database fields, its indexing processes, controlled vocabulary and limits options. These are database properties you need to know, be aware of  and consider when designing search strategies as they may have a material impact on your searches, their construction, execution and rendered outcomes.    

Practice Suggestions

1. Calculate the percentage of PubMed-not-MEDLINE records currently on Ovid MEDLINE.
2. Use the docz.dz command to establish the number of records in the other Ovid databases your institution has subscribed to, for example, Embase on Ovid, APA PsycInfo, Cochrane Database of Systematic Reviews (CDSR), Cochrane CENTRAL Register of Controlled Trials (CENTRAL), KSR Evidence etc.  
3. Run the following docz.dz based search for Embase on Ovid. What does the result tell you about the ‘shape’ of Embase on Ovid? < Click here to run search >. Try also, 

• APA PsycInfo < click here >
• Food Science and Technology Abstracts < click here >
• Cochrane Database of Systematic Reviews (CDSR) < click here >
• Cochrane CENTRAL Register of Controlled Trials (CENTRAL) < click here >
• KSR Evidence < click here >
  
  For each database list two aspects of the database's 'shape' that you had not known before. 

Strategy

docz.dz.

limit 1 to medline

limit 1 to "in data review"

limit 1 to in process

limit 1 to publisher

limit 1 to "pubmed not medline"

nb$.bk.

2 or 3 or 4 or 5 or 6 or 7

An introduction to the system and structure of the controlled vocabulary, based upon medical subject headings, that lies behind the bibliographic database Ovid MEDLINE.

Background

Drawing again on the idea of the ‘size and shape’ of databases, this Focused Search provides an introduction to the structure and system of the MeSH thesaurus. The MeSH thesaurus is a controlled vocabulary, based upon medical subject headings. It has been created and is maintained by the National Library of Medicine (NLM) in the USA. The MeSH thesaurus is a domain specific knowledge base curated by humans, that aids both document classification as well as discoverability and retrieval.

MeSH Structure and System

Ovid MEDLINE is Ovid’s rendering of the PubMed database, it too created and maintained by NLM. The content of this kind of bibliographic database consists, for the most part, of records of documents that have been indexed using a controlled vocabulary. A controlled vocabulary is a hierarchical term classification system where terms, representing a thing or concept, can be located within the controlled vocabulary system, along with its broader and narrower terms. For an informative optical rendering of this enter the search term ‘migraine disorders’ into the MeSH database search box as shown below.

https://www.ncbi.nlm.nih.gov/mesh/?term=migraine+disorders

The returned screen provides detailed background information on the target term. Amid the detail is also an indication of where the target term, here ‘migraine disorders’ appears in the MeSH term hierarchy. In the enhanced diagram below the blue bordered terms represent the broader terms associated with ‘migraine disorders’. By contrast the thinner green bordered expressions are its narrower terms. Which is to say that the idea or concept represented by the MeSH term ‘migraine disorders’ can itself be further broken down into finer ideas or sub-concepts, specifically ‘Alice in Wonderland Syndrome’, ‘Migraine with Aura’, ‘Migraine without Aura’ and ‘Ophthalmoplegic Migraine’.

Understanding the MeSH term constellation for your target terms or terms, and being able to navigate through the thesaurus hierarchy effectively, will greatly assist you in the systematic construction of high quality search queries.

In PubMed the MeSH database is a stand-alone, albeit connected, knowledge resource. By contrast the MeSH thesaurus is fully integrated into the Ovid MEDLINE search experience. MeSH terms can be easily located in the thesaurus hierarchy and narrower terms selected (as well as deselected) either as a group or individually as you decide. When you choose to include all of the MeSH terms narrower terms, you are said to have “exploded” the term. The Explode function and a related function, called Focus will be covered in the next Focused Search, Knowledge Discovery with MeSH (Explode & Focus) – Ovid MEDLINE.

Practice Suggestions:

1. Go to the Advanced Search. Check that the option Map term to Subject Heading is activated, that is ticked, and enter as a Keyword the expression migraine disorders. Looking at the screen that is subsequently displayed, list at least 4 options you could act on from there.
2. Go again to the Advanced Search. Deselect the option Map term to Subject Heading and as before enter as a Keyword the expression migraine disorders. Looking at the screen that is subsequently displayed, what kind of search has Ovid executed? Where do you think Ovid has searched for your term?  
3. In the Focused Search used in this example, how can you verify that the results in line #2 are included in the .mp search, run in line #3?

Strategy

migraine disorders.ti.

migraine disorders.ti,ab.

migraine disorders.mp.

Migraine Disorders/

exp Migraine Disorders/             

exp Migraine Disorders/ or migraine disorders.mp.

How to instruct the database to include narrower terms in a MeSH thesaurus search and/or to retrieve only those terms considered main subject terms.

Background

This Focused Search provides further background on the structure and system of the MeSH thesaurus. The MeSH thesaurus is a controlled vocabulary, based upon medical subject headings. It has been created and is maintained by the National Library of Medicine (NLM) in the USA. The MeSH thesaurus is a domain specific knowledge base curated by humans, that aids both document classification as well as discoverability and retrieval.

MeSH Structure and System
Ovid MEDLINE is Ovid’s rendering of the PubMed database, it too created and maintained by NLM. The content of this kind of bibliographic database consists, for the most part, of records of documents that have been indexed using a controlled vocabulary. A controlled vocabulary is a hierarchical term classification system where terms, representing a thing or concept, can be located within the controlled vocabulary system, along with its broader and narrower terms. Broader terms are those for which your chosen term is a narrower term or sub-concept. Narrower terms on the other hand are the narrower terms or sub-concepts of your chosen term.

Using MeSH for Targeted Searching
We have already seen how, on Ovid, you can use the Advanced Search search mode to locate a term in a specific field (i.e. migraine.ti., see line #1 in this Focused Search) or in a group of fields (i.e. migraine.mp., see line #2).

In the Advanced Search, with mapping turned on (which for most users is a default setting) you can search for a thing not just in terms of the characters that describe it i.e. ‘migraine’, but also in a conceptual sense. That is you are able to automatically include additional terms and phrases that more fully represent the concept that best describes the thing you are looking for. In this Focused Search the entry term for all 10 search lines, using the Advanced Search with mapping turned on, is migraine. With mapping turned on, our search journey starts and continues through the MeSH thesaurus where at various stages we are offered opportunities to expand upon or narrow the scope of our search (see lines #3 to #10).

To investigate this further, let’s consider the following research question and subsequent task.

Is acupuncture effective in the treatment of migraines? Find randomised controlled trials.

From the research question, let us describe the population group as ‘migraine sufferers’ and that by proceeding with the search term ‘migraine’ we are likely to capture a relatively high proportion of relevant documents.

Upon entering the term migraine into the Advanced Search search mode with mapping turned on, Ovid maps our entered term onto a MeSH term, in this case Migraine Disorders/ (see line #3).  Clicking on the MeSH terms displays it in the context of its occurrence and positioning within the controlled vocabulary  as displayed below. Here we can see that Migraine Disorders is a sub-term of the broader term, Headache Disorders, Primary. But Migraine Disorders is itself the broader term for its narrower terms, namely Alice in Wonderland Syndrome, Migraine with Aura, Migraine without Aura and Ophthalmoplegic Migraine.

The returned display, which highlights the mapped to term Migraine Disorders/, also tells us that a specific number of documents, indicated by the search results have been indexed with that specific term. In other words, the concept or idea represented by the term ‘migraine’ within a constellation of scope defining broader and narrower terms, has been identified in the database. This, as opposed to ‘just’ occurrences of the word ‘migraine’ as is the case in lines #1 and #2.

Explode and Focus Options
The MeSH thesaurus, both in terms of its structure and direct integration in Ovid MEDLINE, also facilitates systematic searching. The scope of a selected MeSH term can be expanded upon by selecting the Explode option next to the selected term. See the green highlighting in the screen shot above. MeSH terms displayed in a search strategy with the ‘exp’, as shown in line #5 of the displayed Focused Search, tells us that the total number of records returned for that search line includes the MeSH term along with its narrower terms. By contrast, selecting the Focus option, highlighted in purple above, reduces the scope of the term, whether exploded or not, to records where the selected MeSH term represents one of the main topics as described in the article. The ‘*’ character placed before the MeSH term, as displayed in line #4 , indicates that the search has been run with this more specific requirement in mind. 

MeSH Subheadings
Each MeSH term has a collection of subheadings associated with it. The list of subheadings for the MeSH term Migraine Disorders is displayed in the screen shot below.

As part of MeSH thesaurus construction and maintenance, the indexers at NLM allocate subheadings to MeSH terms. Subheadings provide an additional means of further fine-tuning the context within which the MeSH term, i.e. the concept, is being sought. In the displayed Focused Search, lines #6, #7 and #8 return records that cover Migraine Disorders but specifically those related to the etiology, diagnosis and prevention and control of the condition respectively. It is also possible to select multiple subheadings as shown with respect to therapy, in line #9. 

Practice Suggestions

1. Does the subheading /dh – Diet Therapy include vitamin or mineral supplements? Use the ‘i’ icon next to the subheading to find out.   
2. How many PubMed-not-MEDLINE records would you expect to find in line #5 of the displayed Focused Search? Look at the Focused Search, Database Size and Shape (docz.dz) – Ovid MEDLINE to help you find the answer.
3. Describe what Ovid is doing in line #10 of the displayed Focused Search. In terms of database record status, what type or types of database record are being returned with this search? Would this search also run in Embase on Ovid although it has been formulated using MeSH terms?

Strategy

migraine.ti.

migraine.mp.

Migraine Disorders/

*Migraine Disorders/

exp Migraine Disorders/             

exp Migraine Disorders/et [Etiology]

exp Migraine Disorders/di [Diagnosis]

exp Migraine Disorders/pc [Prevention & Control]

exp Migraine Disorders/dh, dt, th [Diet Therapy, Drug Therapy, Therapy]           

exp Migraine Disorders/ or migraine.mp.

How to use the controlled vocabulary in Ovid MEDLINE to contrast terms, assess their coverage, relevance to the research question and then select them accordingly.

Background

The structure, system and sheer depth of database controlled vocabularies also provides searchers with various means of selecting terms, of considering their relevance and of refining them so that they better suit the search at hand. To illustrate this, let us refer again to the following research question and subsequent task.

Is acupuncture effective in the treatment of migraines? Find randomised controlled trials.

Here we need to consider how to proceed with the term ‘acupuncture’. This Focused Search looks at how the MeSH thesaurus as an highly structured and contextually deep knowledge base can help researchers refine their search terms. And that via Ovid MEDLINE, the MeSH thesaurus knowledge base provides researchers with a means of being able to (a). navigate through it, (b). select specific terms and (c). deselect others.   

Exact versus Near Matches
Entered into the Advanced Search with the mapping turned on, the entry term acupuncture yields a list of MeSH term possibilities as shown in the screen shot below. As marked by the ticked Select box, the entry term acupuncture is an exact match. The other possibilities are near matches.

From this initial display, or by running the MesH term search in Ovid MEDLINE (line #1), it is not possible to determine whether or not Acupuncture/ has narrower terms. Running the term again but with the Explode option activated, indicates that it does not (#2).  However, Acupuncture Therapy/ does have narrower terms (compare lines #3 and #4), terms that might be more appropriate for the research question. 

Learning with Scope Notes
The MeSH thesaurus created and cultivated by the NLM is an exceptionally information laden example of a controlled vocabulary. In addition to a hierarchical term classification scheme, rich structure and subheadings, MeSH terms also have scope notes allocated to them. This MeSH term specific annotation gives an indication of the coverage of the term (from the indexers point of view), flags points to note, provides information on the year of entry of the MeSH term into the thesaurus, indicates any previous indexing, gives references and lists other terms the given MeSH term would additionally capture when used in a search. In this Focused Search example the scope note for Acupuncture Therapy/ helpfully draws a distinction between the term ‘acupuncture’ meaning the specialty as opposed to ‘acupuncture’, a form of therapy. See lines #6 and #7. 

Targeted Term Selection
In contrast to the MeSH term Acupuncture/ which has no narrower terms, Acupuncture Therapy/ has several. However, not all of them might be pertinent to the research question at hand. In Ovid MEDLINE it is possible to fully display the chosen MeSH term and all its narrower terms and their narrower terms, yet only select specific narrower terms. In the screen shot example below the Acupuncture Therapy/ narrower terms Electroacupuncture and Moxibustion as highlighted in red, have been excluded.

Practice Suggestions:

1. How many narrower terms are there for the MeSH term “Drug-Related Side Effects and Adverse Reactions”/?
2. How could you verify that Explode returns narrower terms as well as the narrower term of the narrower terms?
3. Would the MeSH term Deep Learning/ usefully contribute to an investigation on surface versus deep learning in medical education? How could you find out?

Strategy

Acupuncture/

exp Acupuncture/

Acupuncture Therapy/

exp Acupuncture Therapy/

acupuncture therapy/ or acupuncture analgesia/ or acupuncture, ear/ or meridians/ or acupuncture points/

Acupuncture/ [A sub-category of "Health Occupations"]

Acupuncture Therapy/ [A sub-category of "Complementary Therapies"]