Mini-manual for Clinical Questions & Ovid Medline Searching
Prepared by UMKC HSL Clinical Medical Librarians Susan Sanders and Kristy Steigerwalt
Part I - Clinical Questions & PICO Format
Every patient encounter leads to you asking clinical questions about the patient’s diagnosis,
treatment, management, or prognosis. These questions are similar to thinking about a
research project. They require a well-structured, logical question (hypothesis) followed by
a search for information (research), an explanation (discussion) and subsequently, a
decision about what action to take (conclusion). It’s no wonder that clinicians need
information systems to answer questions quickly and accurately. With the deluge of
information, it would be unreasonable to do a database search each time you had a
question, or when seeing a patient. There are systems such as UpToDate, DynaMed, ACP
PIER, and others that help you find information and answers rapidly, but there are good
reasons to learn how to search a biomedical databases such as Medline, CINAHL, or
PsychInfo, to name a few. What are your database search skills at present? What do you
need to learn about clinical questioning and literature searching?
A well-built clinical question usually has four parts, Patient, Intervention, Comparison,
Outcome – known as the PICO format. Here are three case examples to work with on
developing a PICO question.
Case Presentation #1:
The patient is a previously healthy, 81-year old woman with a history of progressive
dyspnea, leg edema and pallor over the last 3 months. She has no chronic conditions, is on
no medications, and requires no assistance. Her exam shows pallor, pitting edema of both
shins, diminished position and vibratory sensation over her feet and ankles, along with the
absence of neck vein distension or S3 gallop. Her chest x-ray is normal. Her test results
show very low hemoglobin, an increased MCV (mean corpuscular volume), and a very low
blood level of vitamin B12. What questions would you ask about this patient?
Patient, Population or Problem
o What are the characteristics of the patient or population?
o What is the condition or disease you are interested in?
Intervention or exposure
o What do you want to do with this patient (e.g. treat, diagnose, observe)?
o What is the alternative to the intervention (e.g. placebo, different drug,
o What are the relevant outcomes (e.g. morbidity, death, complications)?
Case Presentation #2:
Mr. Jones is a 55 year old man. He has just been diagnosed with Type 2 Diabetes.
Although you regularly prescribe Metformin to help regulate blood glucose levels in new
diabetics, Mr. Jones wants to try using regular exercise and diet to improve his blood
sugar. How will you treat him?
Case Presentation #3:
The patient presents with a calcium blood level of 17. She is given normal saline and
furosemide. Her condition improves, but what was the cause of her problem? What would
Part II – Searching the Medline Database to Answer a Clinical Question
MEDLINE is the world’s largest database of indexed journal citations for the health
sciences literature, produced by the National Library of Medicine and National Center for
Biotechnology Information in Bethesda, Maryland. Medline is available in numerous
databases and is a free database through PubMed. There is some free full-text, but not
all. Medline is available through Ovid, Scopus, EBSCO, and other publishers with their own
unique interfaces, or “dashboards.”
Accessing Medline from UMKC’s Library Homepage
To Access Medline from UMKC, go to the library homepage
(http://library.umkc.edu/hslhome), use the dropdown menu and choose “HSL Quick Links”,
then select ”Medline Through Ovid”.
There are many ways to do searches on search engines and in databases. Databases
like Medline use “controlled vocabulary,” known as MeSH (Medical Subject Headings)
terms, Subheadings, and Text Words.
What is MeSH? http://www.nlm.nih.gov/mesh/
1. MeSH is a standardized vocabulary for looking up concepts and terms, and referred
to as the MeSH Tree. There are 16 main categories, or descriptors. Think of
MeSH like an index in the back of a book where “terms” connect you to “pages.”
2. In reality, there are indexers who really read new articles, and assign MeSH terms.
They translate the authors’ non-uniform language into standardized MeSH
3. To put MeSH to its best use, choose the single narrowest subject heading that
corresponds with the information that you are trying to find.
Different Terms, Same MeSH
Title #1, Treatment of gastric cancer.
Title #2, Technical considerations in laparoscopic resection of gastric neoplasms.
MeSH Heading for both titles: Stomach Neoplasms.
Same Term, Different MeSH
Title #1, The diagnosis of plaque-induced periodontal diseases.
MeSH Heading: Dental Plaque
Title #2, Mechanism of senile plaque formation in Alzheimer disease.
MeSH Heading: Senile Plaques
4. Indexers also assign various sub-headings to MeSH Headings.
Subheading – Secondary topic linked to a MeSH term by an indexer.
EXAMPLE: *aortic rupture/su [Surgery] where the subheading is surgery
Use a subheading only if it exactly matches a critical topic of your question.
No subheading chosen? Then the system searches all of them that the indexer
Polycystic ovary syndrome/ge [Genetics] = 700+ citations
Polycystic ovary syndrome AND Genetics [MeSH Major Topic] = 20 citations
Strengths of MeSH:
Standardization (controlled vocabulary) - Searcher doesn’t have to think or type
variations, like aortic rupture, rupture of the aorta, aortic tear, tear of aorta when using
Focus/Major Topic – Find articles where indexer tagged MeSH a major topic; omit
citations where the topic is a minor point. Helps target results, especially in a search for
only 1 topic. When searching two or more topics combined, try without major topic.
Subheadings – Indexer can pre-link 2 topics, e.g. Hernia, hiatal/su [Surgery]. MeSH +
subheading gets better results than hiatal hernia AND surgery, which incorrectly
retrieves irrelevant citations, e.g., hiatal hernia caused by surgery for reflux disease.
Mapping – Mapping is a function of the computer software. It suggests, or matches, your
typed words to a MeSH heading. For best mapping, type each term separately and
combine your searches. If mapping fails to find relevant articles, or in addition to
mapping, search title words, then display MeSH to see what MeSH terms were assigned to
the best results. Ask yourself, “What MeSH did indexers use for this topic?” and go with
what they used.
Weaknesses of MeSH:
1. MeSH headings don’t exist for all topics.
2. Very recent citations don’t have MeSH yet – indexing takes time.
3. Indexers don’t assign MeSH terms to every word in an abstract.
4. New MeSH terms are not retroactive, e.g., Individualized Medicine (2010) will not yield
any pre-2010 results.
5. It is possible to miss the best MeSH terms.
MeSH Tree & Explode and Focus in Ovid Medline.
Look at the MeSH tree above. If you explode a term, the database searches for your
requested subject heading and any more specific terms that are related to your subject
heading. To find out what, if any, narrower topics are associated with your subject heading
(so that you can decide whether or not you want to explode your heading) click on the
heading itself. You will see a new screen that allows you to view the narrower (and
broader) subject terms associated with your topic. This screen shows subject headings in
a "tree" structure. Scroll down to find your subject heading in the tree. The plus (+) sign
next to a topic means that the topic has narrower terms associated with it. You can view
narrower terms by clicking on the plus sign. The number of articles that you can expect to
retrieve for each subject heading is provided after each heading.
From the subject heading screen you can click directly on "hypertension" to view its tree -
related terms that are more general and more specific. If you choose not to explode
hypertension, then you will miss articles that are indexed to more specific forms of
hypertension, such as renal hypertension. Instead, you will only retrieve articles about
hypertension that do not mention these more specific forms of the disease.
The focus command tells the database to retrieve only those articles in which your subject
term is considered to be the primary focus of the article. This will eliminate articles in
which your topic is discussed only peripherally. You will retrieve fewer (but probably more
relevant) articles if you use this feature.
You can explode and focus at the same time. If you check both the explode and focus
boxes next to your subject heading, the database will look for all of the exploded terms
and retrieve articles in which any one of the terms has been designated as the main focus
of the article.
Which term will explode? Neutropenia or Bird Diseases?
MeSH indexers apply subheadings to help further refine your question. The term Angina
Pectoris is assigned these allowable subheadings: /di (diagnosis), / th (therapy), /ep
(epidemiology), and so on. Agina Pectoris would not be assigned the subheading for
therapeutic use, /tu. Any citation assigned the MeSH term Angina Pectoris could be
assigned any or multiple allowable MeSH subheadings, and you need to be careful when
using subheadings because they limit a search. Here’s an example of how a subheading
limited and restricted search results ineffectively.
The patient presents with syncope, and is taking terfenadine, a "non-sedating"
antihistamine. You search for evidence on the risk of syncope in patients taking
antihistamines, and perform this Ovid Medline search:
Line 1: searches for syncope limited to the subheading etiology (ET).
Line 2: searches for Terfenadine and the appropriate group of antihistamines.
Line 3: Boolean AND combines the problem (syncope) and your intervention/exposure
(antihistamines) and yields 6 citations, none of them relevant.
Line 4: backtracking, you run a search filter for etiology or cause
Line 5: now search the disease as a key word (mp).
Line 6: Boolean AND combination of the search filter, disease, and the
intervention/exposure yields 17 citations. Two of these are pertinent including a large
HMO based cohort study.
The problem with the first search was using the wrong subheading for syncope. In the
cohort study that was relevant, syncope carried the subheadings CI (chemically induced)
and EP (epidemiology).
A search of antihistamines/co (complications) would have found nothing because CO is not
an allowable subheading for antihistamines. To find the allowable subheadings use the
"tools" function in Ovid. The subheading used in this article for antihistamines was AE
To become familiar with the indexing take a look at the "complete reference" for articles
which are relevant to your search and you can see exactly which subheadings are used,
then use them yourself.
SEARCHING WITH TEXT WORDS
You can use words from titles, abstracts, authors’ words, names of studies, etc. if no
MeSH matches a topic. Text word searching is a useful supplement to MeSH.
Strengths of text word searching
- Instantly indexed; up-to-date terminology; every title, abstract word searchable
(even low frequency terms); get results even if you miss the best MeSH.
Challenge of text word searching
- Easy to miss information because authors use different words for the same topic.
- Can’t use Explode, Focus, or Subheadings – those features apply only to MeSH
Exercise: See if you can answers this…based on what you have read this far, would
you say Yes or No to the following “Features” when searching with either MeSH or
Text Word? For example, is Standardization a MeSH or a Text Word feature?
Feature MeSH Text Word (Title, Abstract)
Standardization YES NO
Finds Low Frequency Words
Word variations in text word searching
1. Use a truncation character (*) to search different word endings.
o Place an asterisk at the point where the variation begins, e.g. esophag* - retrieves
esophagus, esophageal, esophagitis.
o Type synonyms and other word variations in search box, connected with OR
E.G., Autops* or post-mortem* or postmortem* Typing “or” bypasses
mapping and performs a “Multi-purpose” (.mp) search (title, abstract,
etc.) – works well for text words.
o The asterisk substitutes for a blank space or any number of characters. Can you
think of other instances where it would be useful to use truncation?
o vitamin C – ascorbic acid
o renal failure – kidney failure – renal insufficiency
3. Different spacing and punctuation
o RU486 RU 486 RU-486
4. British Spellings
o e.g., paediatric* oesophag*
5. Break up phrases
o Instead of elder abuse, try abus* AND elder* to retrieve these
abuse of the elderly, elder neglect and abuse, partner abuse among the
o Hartmann* retrieves hartmann’s procedure, Hartmann resection, Hartmann’s
Get help with text word variations
Search MeSH as a major topic then scan results to see word variations in titles.
1. Display the MeSH Scope Note
2. In Advanced Ovid Medline, Click [i] in Mapping or Tree Display - look at “Used For”
Take away: Add text words as safety net for MeSH. When results are important, use
both MeSH and text words.
Example MeSH +Text word search
The MeSH term: “Ebola Vaccines” was established in 2005-add the text word searches
ebola AND vaccin* to get pre 2005 results.
Part III: Putting It Together
1. Search each concept/idea/topic separately (most important first).
2. Create separate results sets for MeSH and text words.
3. Use MeSH mapping; check the Tree display to decide whether to explode; make major
topic (focus) decision; check Subheadings for exact match to search topic. Use
4. Use Text Words – type synonyms, use truncation character, different spellings,
5. Be sure topics in the text word search match topics in MeSH search.
6. If MeSH is Major topic, search text words in title only (major point will be found
7. Use parentheses to avoid logic errors when using AND/OR together, e.g.,
Ovid: 1 AND (5 OR 8)
8. Use Ovid’s key operators & dot commands.
Key Operators in Ovid
* Find alternate endings to nurs* will find nurse,
this word nursing, nurses
.tw. Search for this term in the anxiety.tw.
Title and Abstract fields
Adj Search for one term within patient adj3 will find patient
x number of terms from within three words of
AND Find articles where both smoking AND cessation
OR Find articles where either smoking OR tobacco
9. If Ovid “Cannot map,” temporarily un-check “Map to MeSH” box – OR – type a field
qualifier after the word in the search box: .mp, .ti These are also called Ovid DOT
commands, and more are available in the table (next page).
Ovid DOT Commands 1
10. Full text: First, try “Ovid Full Text” link, if available. If not, click Find it @ UMKC for
UMKC full text. Order free through inter-library loan if not available from UMKC in
either electronic or print.
Last Example! Question: Does dehydration cause delirium at the end of life?