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Systematic Reviews
Susan Fowler, MLISMedical Librarian
pg: 314-360-1069
The beginnings of research synthesis• Karl Pearson is probably the first
medical researcher to use formal techniques to combine data from different studies (1904):– He synthesized data from several
studies on efficacy of typhoid vaccination
• His rationale for pooling data:– “Many of the groups… are far too small
to allow of any definite opinion being formed at all, having regard to the size of the probable error involved.”
Egger et al. Systematic reviews in health care. London: BMJ Publications, 2001.
Prof Archibald Cochrane, CBE (1909 - 1988)
• The Cochrane Collaboration is named in honor of Archie Cochrane, a British researcher.
• In 1979 he wrote, "It is surely a great criticism of our profession that we have not organized a critical summary, by specialty or subspecialty, adapted periodically, of all relevant randomized controlled trials.”
Source: http://www.cochrane.org/cochrane/archieco.htm
Bastian, H., Glasziou, P., & Chalmers, I. (2010). Seventy-five trials and eleven systematic reviews a day: How will we ever keep up? PLoS Medicine, 7(9), 1-11.
Policy and academic milestones in the development of trials and the science of reviewing trials.
The number of systematic reviews in health care, 1990 to 2007.
Bastian, H., Glasziou, P., & Chalmers, I. (2010). Seventy-five trials and eleven systematic reviews a day: How will we ever keep up? PLoS Medicine, 7(9), 1-11.
Evidence at Becker: Systematic Reviews
Reproducibility
A systematic review is just like any other kind of research which means that an independent party can read your lab notes, execute the same actions, and return the same results. If you keep this in mind from the beginning, you will have a much easier time later in the process, when you are writing the article for publication, and when you update the review in the future.
Start Out Right, Stay Organized
Plan AheadDecide as a team what tools to use to stay organized.
Keep…
• detailed records of each search in addition to saving searches in your personal accounts (like your My NCBI account in PubMed)
• all your citations in a citation management program (like EndNote) so you can easily and quickly manipulate them
• a spreadsheet organized by article and sub-organized by preliminary inclusion and exclusion criteria to track why you included and excluded articles for more in-depth review
• detailed notes of in-depth reviews for each article organized by specific criteria
Steps involved for a Systematic Review1. Develop an answerable question
2. Check to see if there is a recent systematic review on your question
3. Agree on specific inclusion and exclusion criteria
4. Develop a system to track and record search methodologies, databases searched, articles
reviewed, why articles were included/excluded in final data synthesis
5. Devise reproducible search methods
6. Launch and track exhaustive search
7. Organize search results
8. Reproduce search results
9. Abstract data into a standardized format
10. Synthesize data using statistical methods (meta-analysis)
11. Write about what you found
Develop an answerable questionPICO (T)
• Patient or problem - How would I describe a group of patients similar to mine?
• Intervention - Which main intervention, prognostic factor, or exposure am I considering?
• Comparison (if appropriate)- What is the main alternative to compare with the intervention?
• Outcome - What can I hope to accomplish, measure, improve or affect?
• Type of Study – Based on my question, what type of study will provide the best answer?
Type of Study
Type of Question Ideal Type of StudyTherapy RCTPrevention RCT > Cohort > Case ControlDiagnosis Prospective, blind controlled
comparison to gold standardPrognosis Cohort > Case Control > Case
Series/Case ReportEtiology/Harm RCT > Cohort > Case Control
How questions influence search results
Relevancy
Retrieval(# of search results)
Broad Questions
Narrow Questions
High = lots of articles
Low = very few articles
High = directly relevant articles
Low = mostly irrelevant articles
Robin Featherstone. (2010). Literature reviews for the health sciences
Access the evidence“A high level of expertise is required tounderstand the technical aspects of datastructure and databases, to narrow the searchto manageable numbers without losingrelevant citations, to access the gray literature, to manage the references, and todocument retrieval methods for the eventualwrite-up of the review. It is advisable to havea professional medical librarian or informationspecialist set up the search terms, using thekey words you have identified, and conductthe search [2,27].”
Haines, T., McKnight, L., Duku, E., Perry, L., & Thoma, A. (2008). The role of systematic reviews in clinical research and practice. Clinics in Plastic Surgery, 35(2), 207-214.
For your search to be thorough, you will need to search several databases like…
•Medline•Embase•CINAHL•CENTRAL•Health Services/Technology Assessment (HSTAT)
Grey Literature…•CADTH•Mednar•Proquest Dissertations and Thesis
Current Trials – clinicaltrials.gov
Hand search print indexes, journal table of contents, and bibliographies
Contact experts in the field
Thoroughness
Appraise the evidenceHow to appraise evidencedepends on the type ofpublication …FRISBE for Therapy…F – Follow UpR – Randomized I – Intention to TreatS – Similar baseline characteristics in
participantsB – BlindedE – Equal – aside from intervention,
were participants treated equally
Time ExpectationsOverall: The average systematic
review requires 18 months of work. “…to find out about a healthcare intervention it is worth searching research literature thoroughly to see if the answer is already known. This may require considerable work over many months…” (Cochrane Collaboration)
Searching: A minimum of two weeks should be planned for each step of the search process and for each database searched.
Resources1.Cochrane Collaboration 2.Cochrane Handbook for Systematic Reviews of Interventions 3.How to read a paper. Greenhalgh, T.; BMJ, 315 (1997) 4.Johns Hopkins Evidence-Based Practice Center 5.Systematic reviews to support evidence-based medicine : How to review and apply findings of healthcare research . Khan, K. S.; London ; Lake Forest, IL: Royal Society of Medicine Press. (2003) 6.Systematic Reviews: CRD’s guidance for undertaking reviews in health care 7.Paul Glasziou, Les Irwig, Chris Bain. (2001). Systematic reviews in health care: A practical guide Cambridge University Press. References Allen, I. E., & Olkin, I. (1999). Estimating time to conduct a meta-analysis from number of citations retrieved. JAMA, 282, 634-635. Center for Outcomes Research and Education. ResearchCORE.org. Retrieved July/27, 2009, from http://www.researchcore.org/faq/answers.php?recID=5Cochrane Collaboration. Cochrane and systematic reviews. Retrieved July 6, 2009, from http://www.cochrane.org/consumers/sysrev.htmGrant, M. J., & Booth, A. (2009). A typology of reviews: An analysis of 14 review types and associated methodologies. Health Information & Libraries Journal, 26(2), 91.Greenhalgh, T. (1997). How to read a paper: Papers that summarise other papers. BMJ, 315, 596-599. Haines, T., McKnight, L., Duku, E., Perry, L., & Thoma, A. (2008). The role of systematic reviews in clinical research and practice. Clinics in Plastic Surgery, 35(2), 207-214. Higgins, J., Green, S., Prof, Cochrane Collaboration & NetLibrary, I. (2008). Cochrane handbook for systematic reviews of interventions. http://www.cochrane-handbook.org/Jesson, J., & Lacey, F. (2006). How to do (or not to do) a critical literature review; Pharmacy Education, 6(2), 139-148. Khan, K. S. (2003). Systematic reviews to support evidence-based medicine : How to review and apply findings of healthcare research. London ; Lake Forest, IL: Royal Society of Medicine Press. Manchikanti, L., Benyamin, R. M., Helm, S., & Hirsch, J. A. (2009). Evidence-based medicine, systematic reviews, and guidelines in interventional pain management: Part 3: Systematic reviews and meta-analyses of randomized trials. Pain Physician, 12(1), 35-72. McGowan, J., & Sampson, M. (2005). Systematic reviews need systematic searchers; Journal of the Medical Library Association, 93(1), 74-80. Shell, L., Hofstetter, S., Carlock, D., & Amani, J. (2006). Survivor's guide for the novice: A simplified model for a collaborative systematic review; Journal of Hospital Librarianship, 6(4), 1-12. University of York, & NHS Centre for Reviews & Dissemination. (2009). Systematic reviews CRDs guidance for undertaking reviews in healthcare.
Questions?
