systematic reviews: principles and processes med 264 mary linn bergstrom nancy stimson
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Systematic Reviews: principles and processesMED 264Mary Linn BergstromNancy Stimson
“A systematic review is a review of a clearly formulated question that uses systematic and explicit methods to identify, select, and critically appraise relevant research, and to collect and analyze data from the studies that are included in the review.Statistical methods (meta-analysis) may or may not be used to analyze and summarize the results of the included studies. Meta-analysis refers to the use of statistical techniques in a systematic review to integrate the results of included studies.”PLOS Medicine v6 issue 7 July 1009 doi:10.1371/journal.pmed.1000097
Types of reviews
• narrative or integrative• systematic
• Describes the methodology in detail; includes search strategy, study selection criteria, assessment of study quality, and data synthesis
• Balancing sensitivity and specificity• meta analysis
• analysis of combined data from quantitative studies with similar methodologies
Sources
Cochrane Collaboration www.cochrane.org
EPPI-Centrehttp://eppi.ioe.ac.uk
Campbell Collaborationwww.campbellcollaboration.org
Cardiff University Library Cochrane Archive
University Hospital Llandough
Standards
IOMInstitute of Medicine of the National Academies – Standards for Systematic Reviews
http://www.iom.edu/Reports/2011/Finding-What-Works-in-Health-Care-Standards-for-Systematic-Reviews/Standards.aspx
PRISMAPreferred Reporting Items for Systematic reviews and Meta-Analyses…an evidence-based minimum set of items for reporting in systematic reviews and meta-analyses
http://www.prisma-statement.org/
Evidence Based Pyramid
http://healthinformatics.wikispaces.com/systematic_review
Formulate Question
• PICO: population, intervention, comparison, outcome
• Check for recent systematic reviews on topic
Inclusion & Exclusion Criteria
Criteria for considering studies for this review
Types of studiesAll randomized controlled trials with parallel or cross-over design, blinded or open-label with a
duration of 24 weeks or longer. Reports of which no full publication exists were considered for inclusion in this review only, if the information available would allow for a publication in accordance with all criteria of the CONSORT statement. Types of participants
People with type 2 diabetes mellitus.Types of interventions
Comparison of long-acting insulin analogues (insulin glargine or insulin detemir) to NPH insulin. In case of a combination therapy (long-acting insulin analogue combined with another antihyperglycaemic drug) the additional antihyperglycaemic agent had to be part of each treatment arm. Only studies reporting on insulin scheme with subcutaneous application were considered for inclusion in this review.Types of outcome measures….
Long-acting insulin analogues versus NPH insulin (human isophane insulin) for type 2 diabetes mellitusCochrane Database of Systematic Reviews 2007DOI: 10.1002/14651858.CD005613.pub3
Select Databases
Reduce bias and improve sensitivity by searching multiple databases PubMed, Cochrane Library, Scopus (for Embase content)
Consider other sources: Grey literature Clinical trial registers Cited reference searching Article bibliographies Hand searching Experts in the field
Develop Search Terms
Brainstorm Review controlled / structured vocabulary in selected
databases Harvest keywords and structured vocabulary indexing terms
from good database records on topic Harvest keywords and structured vocabulary indexing terms
from good articles on topic Use a harvest form (spreadsheet, Word doc, etc.)
PubMed Harvesting Process
For each concept, perform a separate “quick and dirty” search in PubMed
Enter a single concept( MeSH, textword, phrase) in the PubMed search box and run the search
Examine records: Look for MeSH that reflect your major concept Look in title and abstract for author-generated terms (i.e., text words, phrases) that reflect the concept.
Add any new MeSH and text words/phrases into harvesting form Indicate MeSH with the tag [mh]Indicate text word with the tag [tw] title word or abstract word[tiab] [ti] [ab]Use other tags as appropriate, e.g., [pa]
PubMed search field descriptions & tags: http://www.ncbi.nlm.nih.gov/books/NBK3827/#pubmedhelp.Search_Field_Descrip
Create Search Strategy
Strategies will differ in different databases Document search details & results for each database Common errors affect results
conceptualization of research question spelling errors translation of search strategy to different databases missed subject headings missed natural language search terms spelling variants and truncation irrelevant subject headings irrelevant natural language terms search limits
Run Search
Create a selective test database
Run search
Store search results
Compare search results with test database citations
Revise, re-run
Select and Assess Studies
Select studies for inclusion into SR Apply your established inclusion/exclusion criteria Usually conducted in two passes
Review title/abstract Review full-text
Use two independent reviewers with a third person available as ‘tie breaker’ for conflicts
Keep a log of excluded studies with reasons for exclusion
Assess study quality Each study meeting the inclusion criteria is assessed for quality More studies may be excluded in this process Document decisions
Analyze. Interpret, Report
Extract data from the included articles for qualitative or quantitative (meta-analysis) analysis
Analyze, synthesize results
Interpret results Comment on
Strength of the evidence Applicability of the results Benefits/costs/tradeoffs Limitations Implication for future research
Report “Publish the final report in a manner that ensures free public access”
IOM Standards for Systematic Reviews STANDARD 5.3
Meta-analysis
PRISMA
Why document?
Ensure scientific integrity, replicability Documentation is standard practice for any research project
Meet publication standards Investigator must have documentation details for final paper Utilize PRISMA checklist to structure report
Keep your sanity Searching is a complex iterative process completed over an
extended period of time Track internal decision-making affecting search construction
What to document?
The entire process:
• Define question• Formulate search terms and strategies• Select databases & sources• Run searches• Store results in a test database• Revise, re-run• Collect & compare results• Manage data selection• Evaluate evidence, conduct qualitative
and/or quantitative analysis• Prepare and publish final report
See PRISMA 2009 Checklisthttp://www.prisma-statement.org/
How to document?
MED264 course websitehttps://piazza.com/ucsd/fall2014/med264/home
Confirm documentation practices with entire research teamCitation format, etc.
Back up, back up, back up
Figure 1. Flow of information through the different phases of a systematic review
Moher D, Liberati A, Tetzlaff J, Altman DG, et al. (2009) Preferred Reporting Items for Systematic Reviews and Meta-Analyses: The PRISMA Statement. PLoS Med 6(7): e1000097. doi:10.1371/journal.pmed.1000097http://www.plosmedicine.org/article/info:doi/10.1371/journal.pmed.1000097
Mary Linn [email protected]
Nancy [email protected]
http://ucsd.libguides.com/med264_systematic_reviews