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Locating the Evidence

Locating the Evidence. University of Maryland, Health Sciences and Human Services Library. Objectives. Define evidence-based practice Identify resources to support the practice of evidence-based health care Develop strategies for searching for evidence in primary and secondary resources.

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Locating the Evidence

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  1. Locating the Evidence University of Maryland, Health Sciences and Human Services Library

  2. Objectives • Define evidence-based practice • Identify resources to support the practice of evidence-based health care • Develop strategies for searching for evidence in primary and secondary resources

  3. Evidence WHAT IS EBM? “Evidence-based medicine (EBM) requires the integration of the best research evidence with our clinical expertise and our patient’s unique values and circumstances.” Straus SE, Richardson WS, Glasziou P and Haynes RB (2005). Evidence-Based Medicine: How to Practice and Teach EBM.

  4. Evidence-Based Practice de-emphasizes • Use of intuition and unsystematic clinical experience stresses • the examination and application of evidence from clinical research requires • efficient literature searching Centre for Health Evidence http://www.cche.net/usersguides/ebm.asp retrieved 3/24/06

  5. Evidence-Based Process • Ask a specific clinical question • Locate the evidence • Appraise the evidence for its validity and relevance • Apply the results in patient care decisions • Evaluate the process to improve it

  6. Categories of Evidence Questions • Diagnosis – blind comparison of test with gold standard • Therapy – which treatment to administer based on double-blind RCT’s • Prognosis – patient’s future health, life span based on cohort studies • Etiology/Harm – relationship between a disease and possible cause

  7. Classifications of Questions

  8. PICO Model for Clinical Questions • Patient characteristics/population • Intervention/test being considered • Comparison intervention (if any) • Outcome of clinical interest / measure.

  9. DiagnosisQuestion: In patients with suspected pulmonary fibrosis, how does high-resolution CT compare with lung biopsy for establishing the diagnosis?”http://medicine.iupui.edu/iumedpeds • P – pulmonary fibrosis patients • I – high resolution CT • C – lung biopsy • O – accuracy of diagnosis

  10. Therapy Question:Are ACE inhibitors more effective than beta blockers in controlling high blood pressure? • P – Patients with hypertension • I – ACE inhibitors • C – beta blockers • O – reduction in blood pressure http://www2.cochrane.org/reviews/en/ab002003.html

  11. Prognosis Question • Is screening mammography truly effective in detecting breast cancer early and improving mortality rates? http://www2.cochrane.org/reviews/en/ab001877.html

  12. Etiology/Harm Question • Do obstetrical complications during pregnancy increase the likelihood of schizophrenia in the child? http://medicine.iupui.edu/iumedpeds

  13. Types of Research Studies • Randomized Controlled Trial • Cohort Study • Case Control Study • Case Reports

  14. Evidence-Based Resources • Systematic review • Very structured format • Meta-analysis • Statistics used to evaluate studies • Practice guidelines • Secondary resources • BMJ Clinical Evidence, Point of care online services (e.g. Dynamed, UpToDate?, ACP Pier), ACP Journal Club, AHRQ

  15. Cochrane Database of Systematic Reviews • Review Groups – over 50 • “A systematic review identifies an intervention for a specific disease …and determines whether or not this intervention works. To do this authors locate, appraise and synthesize evidence from as many relevant scientific studies as possible. They summarize conclusions about effectiveness, and provide a unique collation of the known evidence on a given topic, so that others can easily review the primary studies for any intervention.” • From Cochrane Collaboration, http://www3.interscience.wiley.com/cgi-bin/mrwhome/106568753/ProductDescriptions.html

  16. Evidence Pyramid http://healthlinks.washington.edu/ebp/ebptools.html

  17. Resources:Where is the Evidence Found? • Evidence Based Medicine Reviews Database includes: • Cochrane Database of Systematic Reviews • Cochrane Register of Controlled Trials • DARE – Database of Abstracts of Reviews of Effectiveness • ACP Journal Club • AHRQ Evidence Reports • ACP Pier • National Guideline Clearinghouse • Clinicaltrials.gov • TRIP Database

  18. Database of Abstract of Reviews and Effects (DARE) “DARE covers a broad range of health related interventions and includes over 3000 abstracts of reviews in fields as diverse as diagnostic tests, public health, health promotion, pharmacology, surgery, psychology and the organization and delivery of health care. DARE complements the Cochrane Database of Systematic Reviews by quality-assessing and summarizing reviews that have not yet been carried out by The Cochrane Collaboration.”

  19. Cochrane Central Register of Controlled Trials (CENTRAL) “CENTRAL includes details (and abstracts) of published articles taken from…MEDLINE and EMBASE, and other published and unpublished sources.”

  20. ACP Journal Club “ACP Journal Club's general purpose is to select from the biomedical literature articles that report original studies and systematic reviews that warrant immediate attention by physicians attempting to keep pace with important advances in internal medicine.” From:http://www.acpjc.org/shared/purpose_and_procedure.htm

  21. Resources:Where is the Evidence Found? • Medline • PubMed • CINAHL

  22. Tips for Searching Medline • Search using specific publication types: • systematic review, randomized controlled trial, meta-analysis • Search Cochrane as a journal title and combine with your subject • Use the EBM Reviews limit • Use the Clinical Queries limit

  23. Tips for Searching PubMed • Use advanced search for publication types clinical trial, meta-analysis, practice guideline, randomized controlled trial or review • Use “clinical queries” for methodology filters and systematic reviews option • Narrow, specific (more precise, less retrieval) or broad, sensitive (more retrieval, may contain less relevant items)

  24. Tips for Searching CINAHL • Combine the results of your search with the subject heading Meta-analysis AND/OR • Limit the results of your search to the research, systematic review or clinical trial publication type • Search journals for Cochrane…and combine with topic

  25. Tips for Searching Cochrane • Search keywords, since not indexed with MeSH • Default is a phrase search • You can search “cochrane database of systematic reviews” as a journal title in Medline • Usual updating is quarterly • Mainly RCT’s • Meta-analysis used to statistically combine small studies

  26. Evaluating the Results • Knowledge of basic statistics useful • Therapy: best evidence found in double-blind RCT’s • Diagnosis: controlled trials that compare to the “gold standard” • Etiology: cohort studies • Prognosis: cohort or case control studies

  27. Evaluating the Clinical Literature • A Simple Method for Evaluating the Clinical Literature From American Family Physician

  28. Consider Bias • As much as 50% of studies are never published • Statistically significant, “positive” results are: • More likely to be published: publication bias • More likely to be published rapidly: time lag bias • More likely to be published more than once: multiple publication bias • More likely to be cited by others: citation bias

  29. Review • EBM Resources • Evidence Guide from HS/HSL • Types of EBM questions • Types of research studies • Search strategies in databases • Evaluation of results • Questions?

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