Lost in translation...?

Transferring bio-medical literature searches

between databases and across interfaces

Janette Camosso-StefinovicInformation Librarian

University of Leicester

A forum for discussion

• Sharing ideas with peers

• Learning from others’ experiences

‘Beyond MEDLINE’

• Evidence Based Medicine (EBM)

• Often need to look beyond a single source for evidence to answer a clinical question

• Having identified relevant resources…

• Develop a search strategy in one database, to then adapt it for use in other databases

Time frame for searching

• 6 months ?

• 6 weeks ?

• 2 weeks ?

• 1 week ?

• 1 day ?

• 1 hour ?

Searching for different purposes

• The purpose / question will dictate the depth and scope of a literature search

A question requiring a quick answer …

… a systematic review

• Consider time, access, other constraints

A myriad of sources: Casting your net

A myriad of sources... Where to start?

• Some sources bring different kinds of evidence together – one or two search terms suffice to get a broad picture

• At times, a more detailed search strategy may be useful to answer your question – many search terms, combined together

Searching different interfaces (platforms)

• Changes in access may mean having to transfer a search strategy from

one interface…

for example: EMBASE Ovid

to another…

for example: EMBASE Dialog

Oring (Boolean OR)

• The way search lines are ORed differs across sources:

• The Boolean ‘OR/’ shortcut is supported in MEDLINE and EMBASE (Ovid):

or/1-5

• In CINAHL (Dialog):

1 or 2 or 3 or 4 or 5…

• In Cochrane CENTRAL:

#1 or #2 or #3 or #4 or #5…

Searching different databases

• Even when searching databases via the same interface, databases may differ in underlying indexing structure

• Not always straightforward!

Getting into a MeSH!

• Indexing terms: similarities and differences - across MEDLINE (MeSH) and EMBASE (EMTREE) for example

• The case of gestational diabetes: preco-ordinated subject headings (Screenshot 1)

• Use the Notes to check the scope

Re-running versus starting from scratch

• Re-running a search (where possible)…

• What are the advantages?

• The disadvantages?

Discussion (5 minutes)

An example from urology

• Differences in indexing between MEDLINE and EMBASE

• Sometimes an indexing term does not transfer across (Screenshots 2 - 4)

• Use ‘Map Term to Subject Heading’ function to identify suitable indexing terms (Screenshot 5)

Indexing reflects database scope

• Databases differ in scope (ERIC=education-related topics; BIOSIS=biological sciences and biomedicine)

• To some extent, indexing reflects this

• EMBASE - many indexing terms for drug administration

• PsycINFO - a variety of indexing terms for mental health topics, relationships, etc.

• If they are there, and are relevant, use them

Indexing changes over time

• New terms added continuously

• E.g. MeSH “Echinacea” introduced in 2000

• New MeSH headings are not applied retrospectively to MEDLINE

• A search relying just on this indexing term would miss citations indexed before 2000

• A good reason to include a mix of free text and indexing terms in your search

In the absence of indexing…

• Some databases have no underlying thesaurus…

• Sci Citations (Web of Knowledge) is an example

• Can only be searched using free text

Example from a Cochrane Review

Title: Clarke M, Hopewell S, Juszczak E, Eisinga A, Kjeldstrøm M. Compression stockings for preventing deep vein thrombosis in airline passengers. Cochrane Database of Systematic Reviews 2006, Issue 2. Art. No.: CD004002. DOI: 10.1002/14651858.CD004002.pub2.

Objectives: To assess the effects of wearing compression stockings versus not wearing them among people travelling on flights lasting at least four hours.

‘Thought showering’ exercise

• Using the term…

“aeroplane”

…as a starting point, list as many synonyms and quasi-synonyms as you can think of which could be useful in a search for this question.

Indexing and free text terms

• Good idea to use a combination of both

• BUT - Science Citation Index has no thesaurus to aid the searcher

• So, productive results will require skillful keyword searching

• Thinking of variant and synonymous terms would be essential to search this particular source effectively

Search strategy tailored to each database

• Note the different truncation symbols:• aviation or aviator$ or airline$ or aeroplane$

(EMBASE)• aerospace* or aviation or aviator* (Sci Cit Index)• aerospace? OR aviat? OR airline? OR aeroplane?

(Dissertation Abstracts Online)• aviation OR aviator OR aviators OR airline OR

airlines OR aeroplane OR aeroplanes (OLDMEDLINE: no truncation)

Relevant indexing terms in MEDLINE

1 AEROSPACE MEDICINE/2 TRAVEL/3 AIRCRAFT/4 AVIATION/5 TRANSPORTATION/6 (aviation or aviator$ or airline$ or aeroplane$ or aircraft$ or plane$ or flying or flight$ or travel$ or passenger$).ti,ab.7 (long-haul or long haul or long-distance$ or long distance$ or non-stop…

Iterative searching

• Inserting newly uncovered terms into strategy (identified in 2nd, 3rd database searched, or spotted in relevant papers?)

• Thinking laterally / being creative

• Searching: at times as much an art as a science...

• Develop a network of experts you can call upon for advice

Ask!Part of a very useful search string, for socio-economic deprivation, provided by a colleague:

39. ((low or lower or less or poor or poorer) adj2 (socioeconomic or education:)).tw.

40. deprived communities.ti,ab.

41. minority groups/

42. (Jarman adj3 index).ti,ab.

43. (Townsend adj3 index).ti,ab.

44. (Carstairs adj3 index).ti,ab.

45. poverty.ti.

46. or/1-45

Conclusion 1: Think PICO

• Plan before you begin:

Think of your search question in terms of PICO (Population, Intervention, Comparison and Outcome)

• Keep your eye on the question:

Refer back to your PICO throughout database searching, to stay on track

Conclusion 2: Look beyond a single source

• Don’t rely on one source of evidence, unless you need an overview (e.g. NLH SSE, Hitting the Headlines)

• If time allows, searching a number of sources is good practice

• It also serves as a ‘check’

• For some types of research, it is expected

Conclusion 3: Be aware of differences...

• Between platforms - truncation, management of subheadings, etc.

• Between databases - searching functionalities, different indexing, scope... free text mapping, pros and cons of re-running strategies, running searches in 2+ databases concurrently

• Use ‘Help’ menu if unsure: changes which affect searching should be described there

Conclusion 4: Make use of indexing, don’t be blinded by it

• Don’t rely on indexing alone!

• Think of synonyms, alternative spelling, acronyms, new terminology recently introduced to the literature…

• Your collection of free text terms will serve as a ‘safety net’, and may be essential in some databases

Conclusion 5

• Check the scope notes, if available

• Practice iterative searching: feed in useful terms you uncover along the way, to improve your strategy

• Be creative

• Think laterally

• Network: share your problems, and your solutions