Locating studies for your Systematic review


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  • Bias mitigates against good systematic reviews - you will be covering its causes and detection in more detail tomorrow, but briefly: reports in languages other than English are less likely to be published, or read once they are. There is a tendency to read only reports in journals with high impact factors, and which are indexed in easily accessible databases such as MEDLINE As mentioned before, many reports fail to make it past the conference presentation stage due to funding problems, the fact that they are reporting negative or “uninteresting” results, or the fact that the authors first language is not English, so making it difficult for them to write a full paper for English language journals.
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  • Locating studies for your Systematic review

    1. 1. Locating studies for your systematic review Ruth Mitchell and Gail Higgins
    2. 2. What are we trying to achieve? <ul><li>Up-to-date, relevant, unbiased systematic reviews of the effects of interventions for particular health care problems </li></ul>
    3. 3. How do we achieve this? <ul><li>Locate all possible randomised controlled trials of interventions for these health care problems </li></ul>
    4. 4. Locating all possible RCTs <ul><li>Sources </li></ul><ul><ul><li>electronic databases </li></ul></ul><ul><ul><li>handsearching </li></ul></ul><ul><ul><li>reference lists </li></ul></ul><ul><ul><li>personal communication </li></ul></ul>
    5. 5. Use a strategic approach <ul><li>Start at highest yield source and work down </li></ul><ul><li>Electronic databases </li></ul><ul><ul><li>Cochrane Review Group register </li></ul></ul><ul><ul><li>Cochrane Controlled Trials Register </li></ul></ul><ul><ul><li>MEDLINE </li></ul></ul><ul><ul><li>EMBASE </li></ul></ul><ul><ul><li>Other appropriate databases </li></ul></ul><ul><li>H andsearching (reference lists, conference proceedings) </li></ul><ul><li>Personal communication </li></ul>
    6. 6. Minimise bias <ul><li>Sources of bias </li></ul><ul><ul><li>language </li></ul></ul><ul><ul><li>source (which journal, database etc) </li></ul></ul><ul><ul><li>publication status (full article, conference abstract, unpublished etc) </li></ul></ul>
    7. 7. Designing a search strategy <ul><li>Two-stage process: </li></ul><ul><ul><li>Formulate your question </li></ul></ul><ul><ul><li>Identify your key concepts </li></ul></ul>
    8. 8. Formulate your question <ul><li>Translate the clinical problem into a structured question and identify key concepts </li></ul><ul><li>e.g. Is cannabis effective in treating pain? </li></ul>Standard Rx or placebo Cannabis Pain Comparison Intervention Clinical Problem
    9. 9. Identify your search terms (i) <ul><li>Select database e.g. MEDLINE, and identify the subject headings that match your key concepts </li></ul>Standard Rx or placebo Cannabis Pain Comparison Intervention Clinical Problem
    10. 10. Identify your search terms (ii) <ul><li>Use “text words” for </li></ul><ul><ul><li>synonyms </li></ul></ul><ul><ul><ul><li>e.g. bed sore (decubitus ulcer) </li></ul></ul></ul><ul><ul><li>spelling </li></ul></ul><ul><ul><ul><li>e.g. fetal (foetal) </li></ul></ul></ul><ul><ul><ul><li>marijuana or marihuana </li></ul></ul></ul>
    11. 11. Identify your search terms (iii) <ul><li>Add the type of study you want </li></ul><ul><ul><li>e.g. randomised controlled trial </li></ul></ul><ul><li>For Cochrane systematic reviews </li></ul><ul><ul><li>use the Cochrane highly sensitive search strategy for randomised controlled trials in MEDLINE </li></ul></ul>
    12. 23. Randomised Controlled Trials Cochrane Search Strategy 506,604 Pain (MeSH headings OR text words) 201,806 Cannabis (MeSH headings OR text words) 10,507 AND AND AND 31
    13. 24. Tips for saving time and effort <ul><li>Look at the terms used in citations you know are relevant </li></ul><ul><li>Add search terms to your strategy, use on part of a database, and see what you get back </li></ul><ul><li>Don’t search before an intervention was invented </li></ul><ul><li>Get up-to-date advice from someone who knows </li></ul>
    14. 25. When do we stop searching? <ul><li>No right answer, be guided by </li></ul><ul><ul><li>The return you’re getting </li></ul></ul><ul><ul><li>Resources </li></ul></ul><ul><ul><li>Time constraints </li></ul></ul>
    15. 26. Documenting your search <ul><li>Important so you can remember what you’ve done </li></ul><ul><li>Important for users of your review </li></ul><ul><li>Document </li></ul><ul><ul><li>what you searched </li></ul></ul><ul><ul><li>when you searched </li></ul></ul><ul><ul><li>how you searched </li></ul></ul>
    16. 27. Anticoagulants for heart failure in sinus rhythm
    17. 29. Managing references <ul><li>Use specialised software e.g. ProCite, EndNote, IdeaList, Reference Manager </li></ul><ul><ul><li>saves typing </li></ul></ul><ul><ul><li>reduces transcription errors </li></ul></ul><ul><ul><li>helps identify duplicates </li></ul></ul><ul><ul><li>helps keep track of studies </li></ul></ul>
    18. 30. Don’t be shy – ask for help! <ul><li>Retrieving studies is not simple </li></ul><ul><li>Ask your C ollaborative Review Group ’s Trials Search Coordinator for advice </li></ul><ul><li>Section 5 of the Reviewers’ Handbook </li></ul><ul><li>Medical librarians </li></ul>