Locating studies for your Systematic review
Transcript of Locating studies for your Systematic review
Locating studies for your systematic review
Ruth Mitchelland Gail Higgins
What are we trying to achieve?
● Up-to-date, relevant, unbiased systematic reviews of the effects of interventions for particular health care problems
How do we achieve this?
● Locate all possible randomised controlled trials of interventions for these health care problems
Locating all possible RCTs
● Sources◆ electronic databases◆ handsearching◆ reference lists◆ personal communication
Use a strategic approach
● Start at highest yield source and work down● Electronic databases
◆ Cochrane Review Group register◆ Cochrane Controlled Trials Register◆ MEDLINE◆ EMBASE◆ Other appropriate databases
● Handsearching (reference lists, conference proceedings)
● Personal communication
Minimise bias
● Sources of bias◆ language◆ source (which journal, database etc)◆ publication status (full article, conference
abstract, unpublished etc)
Designing a search strategy
● Two-stage process:
◆ Formulate your question
◆ Identify your key concepts
Formulate your question● Translate the clinical problem into a
structured question and identify key concepts
e.g. Is cannabis effective in treating pain?
Standard Rx or placebo
CannabisPainComparisonInterventionClinical Problem
Identify your search terms (i)● Select database e.g. MEDLINE, and
identify the subject headings that match your key concepts
Standard Rx or placebo
CannabisPainComparisonInterventionClinical Problem
Identify your search terms (ii)
● Use “text words” for
◆ synonyms – e.g. bed sore (decubitus ulcer)
◆ spelling – e.g. fetal (foetal)– marijuana or marihuana
Identify your search terms (iii)
● Add the type of study you want ◆ e.g. randomised controlled trial
● For Cochrane systematic reviews ◆ use the Cochrane highly sensitive search
strategy for randomised controlled trials in MEDLINE
RandomisedControlled Trials
Cochrane SearchStrategy506,604
Pain(MeSH headings
OR text words)
201,806
Cannabis(MeSH headings
ORtext words)
10,507
ANDAND
AND
31
Tips for saving time and effort
● Look at the terms used in citations you know are relevant
● Add search terms to your strategy, use on part of a database, and see what you get back
● Don’t search before an intervention was invented
● Get up-to-date advice from someone who knows
When do we stop searching?
● No right answer, be guided by◆ The return you’re getting◆ Resources◆ Time constraints
Documenting your search● Important so you can remember what
you’ve done● Important for users of your review● Document
◆ what you searched ◆ when you searched ◆ how you searched
Anticoagulants for heart failure in sinus rhythm
Managing references
● Use specialised software e.g. ProCite, EndNote, IdeaList, Reference Manager
◆ saves typing ◆ reduces transcription errors◆ helps identify duplicates◆ helps keep track of studies
Don’t be shy – ask for help!
● Retrieving studies is not simple● Ask your Collaborative Review Group’s
Trials Search Coordinator for advice● Section 5 of the Reviewers’ Handbook● Medical librarians