meri snowdon what’s all this mesh? an introduction to medical subject headings

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Page 1: Meri Snowdon What’s all this MeSH? An introduction to Medical Subject Headings

Meri Snowdon

What’s all this MeSH?

An introduction toMedical Subject Headings

www.bradfordvts.co.uk

Page 2: Meri Snowdon What’s all this MeSH? An introduction to Medical Subject Headings

Meri Snowdon

From the guru of EBM -

‘MEDLINE is the best general source of current best evidence at present because of its breadth and constant maintenance. Thus, it is important to evidence-based practice that clinicians develop and hone MEDLINE searching skills and acquire local access.’

Evidence-based Medicine: how to practice & teach EBM - Sackett D L et al 1998

Page 3: Meri Snowdon What’s all this MeSH? An introduction to Medical Subject Headings

Meri Snowdon

Medline

Library (Ovid windows) Hospital network (Knowledge

Finder) BMA (Ovid web) PubMed (web) Internet Grateful Med (web) Other (Silver Platter, Dialog .....)

Page 4: Meri Snowdon What’s all this MeSH? An introduction to Medical Subject Headings

Meri Snowdon

Three great lies ...

The cheque is in the post

Of course I’ll still respect you in the morning

MeSH is exciting

Page 5: Meri Snowdon What’s all this MeSH? An introduction to Medical Subject Headings

Meri Snowdon

MeSH

Removes the uncertainty– Have I thought of all the synonyms?– Have I tried all the spellings?– Have I included all the variants?– Did the author use my term(s) at all?

Page 6: Meri Snowdon What’s all this MeSH? An introduction to Medical Subject Headings

Meri Snowdon

Playing the game

The indexers set the rules - you have to play by them!

Page 7: Meri Snowdon What’s all this MeSH? An introduction to Medical Subject Headings

Meri Snowdon

From broad to specific

Start off by being inclusive - keep it broad

THEN narrow it down by using limits

Narrowing too soon will make you miss things

Page 8: Meri Snowdon What’s all this MeSH? An introduction to Medical Subject Headings

Meri Snowdon

The tree structure

Respiratory tract diseases– Bronchial Diseases

Asthma– Asthma, Exercise-Induced– Status Asthmaticus

– Ciliary Motility Disorders ....................

– Laryngeal Diseases ......................

Page 9: Meri Snowdon What’s all this MeSH? An introduction to Medical Subject Headings

Meri Snowdon

No misspelt MeSH

MeSH terms are never misspelt as they are entered automatically not manually

Page 10: Meri Snowdon What’s all this MeSH? An introduction to Medical Subject Headings

Meri Snowdon

The most specific term

Intestinal neoplasms 591– Cecal neoplasms 136– Colonic neoplasms 4929– Duodenal neoplasms 385– Ileal neoplasms 227– Intestinal polyps 260– Jejunal neoplasms 189– Rectal neoplasms 2189

Page 11: Meri Snowdon What’s all this MeSH? An introduction to Medical Subject Headings

Meri Snowdon

Exploding

Bronchial Diseases– Asthma

Asthma, Exercise-Induced

Status Asthmaticus

Page 12: Meri Snowdon What’s all this MeSH? An introduction to Medical Subject Headings

Meri Snowdon

Difficult asthma (a letter)*Asthma/px [Psychology]Asthma/th [Therapy]ChildHumanPractice GuidelinesPsychology, Social

Page 13: Meri Snowdon What’s all this MeSH? An introduction to Medical Subject Headings

Meri Snowdon

Focus (& textwords)

1 *asthma 75172 asthma/ 91083 asthma.tw. 97954 1 not 3 10005 2 not 3 17806 3 not 2 2467

Page 14: Meri Snowdon What’s all this MeSH? An introduction to Medical Subject Headings

Meri Snowdon

Friedrich Wilhelm I and porphyria

‘The diagnosis of porphyria was not recognized then and other names were used such as ..... asthma spasmodica flatulentum .....’

Page 15: Meri Snowdon What’s all this MeSH? An introduction to Medical Subject Headings

Meri Snowdon

Subheadings for Asthma classification complications diagnosis epidemiology prevention & control psychology surgery ...........................

Page 16: Meri Snowdon What’s all this MeSH? An introduction to Medical Subject Headings

Meri Snowdon

Exploding subheadings

Therapeutic use tu.xs.

– administration & dosage

– adverse effects– contraindications– poisoning

Page 17: Meri Snowdon What’s all this MeSH? An introduction to Medical Subject Headings

Meri Snowdon

Exploding subheadings

Diagnosis di.xs

– pathology– radiography– radionuclide

imaging– ultrasonography

Pharmacology ph.xs.

– admin & dosage– adverse effects– contraindications– diagnostic use– pharmakinetics– poisoning– toxicity

Page 18: Meri Snowdon What’s all this MeSH? An introduction to Medical Subject Headings

Meri Snowdon

Combining

1 *self-help groups 4452 support groups.tw. 2573 *asthma 77084 1 or 2 6155 3 and 4 66 self-help groups/ 7987 6 and 3 68 7 not 5 2

Page 19: Meri Snowdon What’s all this MeSH? An introduction to Medical Subject Headings

Meri Snowdon

OR is MORE

Page 20: Meri Snowdon What’s all this MeSH? An introduction to Medical Subject Headings

Meri Snowdon

Limits

Local holdings (for library only) Age groups Publication types Language Year of publication Human/animal etc

Page 21: Meri Snowdon What’s all this MeSH? An introduction to Medical Subject Headings

Meri Snowdon

Still too much?

Use the most specific subject headings

Use focus Use subheadings Use AND Use limits Restrict textword searching to title

Page 22: Meri Snowdon What’s all this MeSH? An introduction to Medical Subject Headings

Meri Snowdon

Or too little?

Use OR Use explode Use All Subheadings Don’t use focus Consider synonyms, alternative

spellings or truncation

Page 23: Meri Snowdon What’s all this MeSH? An introduction to Medical Subject Headings

Meri Snowdon

And always remember

Check the MeSH headings used for the most relevant articles and add them to your search if necessary.

You cannot find what is not there!

Page 24: Meri Snowdon What’s all this MeSH? An introduction to Medical Subject Headings

Meri Snowdon

Sensitivity and Specificity If a search is too

sensitive, it will retrieve too much irrelevant material

If a search is too specific, it will miss relevant material

Page 25: Meri Snowdon What’s all this MeSH? An introduction to Medical Subject Headings

Meri Snowdon

WHY are you searching? Do you want one

decent article on a topic?

Do you need evidence?

Are you writing a letter/book/article/systematic review?

Page 26: Meri Snowdon What’s all this MeSH? An introduction to Medical Subject Headings

Meri Snowdon

WHAT are you looking for?

Systematic reviews

Clinical trials Traditional reviews Guidelines General

information Letters

Page 27: Meri Snowdon What’s all this MeSH? An introduction to Medical Subject Headings

Meri Snowdon

Look in the right place

Full-text systematic reviews - on CL All Medline clinical trials + others are

in Cochrane Controlled Trials Register Cochrane looks only at

EFFECTIVENESS Medline includes a very wide range of

publications & can answer a wide range of questions

Page 28: Meri Snowdon What’s all this MeSH? An introduction to Medical Subject Headings

Meri Snowdon

The right place to look

Cochrane Library for effectiveness questions - diagnosis, prognosis, treatment

Medline for other questions - general information, epidemiology, aetiology, surgical techniques etc

Page 29: Meri Snowdon What’s all this MeSH? An introduction to Medical Subject Headings

Meri Snowdon

MeSH on Cochrane Library Many items on the CL are indexed

with MeSH terms BUT not all of them are SO the offical recommendation is

to use MeSH and textword searching combined

Page 30: Meri Snowdon What’s all this MeSH? An introduction to Medical Subject Headings

Meri Snowdon

Text word searching

Looks for exact matchesDoesn’t allow for

– variants - pregnancy, pregnant, pregnancies– alternative spellings - diarrhoea, diarrhea– synonyms - preterm birth, premature birth;

cancer, neoplasm

Apart from Knowledge Finder which uses fuzzy logic

Page 31: Meri Snowdon What’s all this MeSH? An introduction to Medical Subject Headings

Meri Snowdon

FieldsThe different parts of each item on a database are called fields, and most can be searched individually. In Ovid

– ti = title– au = author– ab = abstract– tw = textword (title or abstract)– in = institution– pg = page

Page 32: Meri Snowdon What’s all this MeSH? An introduction to Medical Subject Headings

Meri Snowdon

What you miss

oral thrush 27 candidiasis, oral/ 412

breast cancer 13879 breast neoplasms/ 18754

Page 33: Meri Snowdon What’s all this MeSH? An introduction to Medical Subject Headings

Meri Snowdon

What you miss??

heart attack 236 myocardial infarction 11040

myocardial infarction/ 10091

= 949 irrelevant articles - at least!!

Page 34: Meri Snowdon What’s all this MeSH? An introduction to Medical Subject Headings

Meri Snowdon

Stop words

Many common, normally insignificant, words are ignored in free text searching. This can be a problem when looking for concepts such as ‘out-of-hours’ or ‘after-hours’. There is no way round this unless there is a relevant subheading. In this case there isn’t!!

Page 35: Meri Snowdon What’s all this MeSH? An introduction to Medical Subject Headings

Meri Snowdon

Hyphens

Different systems treat these in different ways. They may be ignored or treated as spaces or treated as hyphens.

To be safe try all options eg– postnatal– post natal– post-natal

Page 36: Meri Snowdon What’s all this MeSH? An introduction to Medical Subject Headings

Meri Snowdon

Mizspellins

Ray & Vermeulen found a total of 200 instances of 10 misspelt textwords in Medline between 1966 and 1996.

Ray J G & Vermeulen M JBMJ 1996 313:1658-9

Page 37: Meri Snowdon What’s all this MeSH? An introduction to Medical Subject Headings

Meri Snowdon

1996-1999

antibotics 4 asprin 1 dopler 2 cholestrol 1 thrombolism 3 myocardial infraction 34

Page 38: Meri Snowdon What’s all this MeSH? An introduction to Medical Subject Headings

Meri Snowdon

haemorrhage??

hamorrhage 1 haemorhage 3 hemorhage 1

and no doubt there’s more!!

Page 39: Meri Snowdon What’s all this MeSH? An introduction to Medical Subject Headings

Meri Snowdon

Truncation

This can be used to overcome some of the problems of free text searching. Different wild cards are used by different systems. Mainly * $ and ?

Can be used at the end of a word for truncation eg pregnan$ or in the middle for spelling variants eg wom?n, an?emia

Page 40: Meri Snowdon What’s all this MeSH? An introduction to Medical Subject Headings

Meri Snowdon

Textword advantages

New concepts eg new drugs British concepts eg clinical

governance, Project 2000 Tradenames

MeSH headings are updated annually

Page 41: Meri Snowdon What’s all this MeSH? An introduction to Medical Subject Headings

Meri Snowdon

Further reading

Sackett D L et al - Evidence-based medicine: how to practice & teach EBM. Churchill Livingstone, 1998

Roberts R - Information for evidence-based care. Radcliffe, 1999

Chambers R - Clinical effectiveness made easy. Radcliffe, 1998