Evidence Based Review

Evidence Based Review
Introduction to Evidence Based Reviews
• Systematic reviews comprehensively examine the
medical literature,
– seeking to identify and synthesize all relevant information
– formulate the best approach to diagnosis or treatment. Examples
are many of the systematic reviews of the Cochrane
Collaboration or BMJ's Clinical Evidence compendium.
• The best clinical review articles base the discussion on
existing systematic reviews and meta-analyses,
– incorporate all relevant research findings about the management
of a given disorder.
– provide readers with powerful summaries and sound clinical
Am Fam Physician 2002;65:251-8.
Key Elements of Evidence Based Reviews
• Topic Selection
• Searching the Literature
• Patient-Oriented vs. Disease-Oriented
• Evaluating the Literature
• Levels of Evidence
Am Fam Physician 2002;65:251-8.
Topic Selection
• Choose a common clinical problem and avoid
topics that are rarities or unusual manifestations
of disease or that have curiosity value only.
• Whenever possible, choose common problems
for which there is new information about
diagnosis or treatment.
• Emphasize new information that, if valid, should
prompt a change in clinical practice.
Am Fam Physician 2002;65:251-8.
Patient-Oriented (POEM) vs. DiseaseOriented Evidence (DOE)
• Concept of Patient-Oriented Evidence that Matters (POEM), in
distinction to Disease-Oriented Evidence (DOE).
– POEM deals with outcomes of importance to patients, such as changes
in morbidity, mortality, or quality of life.
– DOE deals with surrogate end points, such as changes in laboratory
values or other measures of response.
– Although the results of DOE sometimes parallel the results of POEM,
they do not always correspond
• When possible, use POEM-type evidence rather than DOE.
• When DOE is the only guidance available, indicate that key clinical
recommendations lack the support of outcomes evidence.
Am Fam Physician 2002;65:251-8.
Levels of Evidence
Am Fam Physician 2002;65:251-8.
Systematic review and Meta-analysis
• Systematic review: Comprehensive literature
search and critical appraisal of individual
studies and uses appropriate statistical
techniques to combine these valid studies.
• Meta-analysis: Studies with relevant data are
identified. Eligibility criteria for inclusion and
exclusion of the studies are defined. Data are
abstracted. Abstracted data analyzed
• … systematic literature review with various search terms and
hand searched online journals and scanned reference lists of
identified citations. We restricted the search to Medline (Ovid),
Embase, CINAHL, Global Health, Web of Science, WHOLIS,
LILACS, IndMed, grey literature (SIGLE), and Chinese
language databases and to studies published between 1995,
and 2010. Panel 1 shows study eligibility criteria. No language
or publication restrictions were applied.
• Two authors independently did the literature search and
extracted data. Any disagreements were resolved after
discussion. We invited participation of other researchers and
contacted authors of published studies who had done similar
population-based studies of paediatric influenza….
Comments by Zambon M, Health Protection Agency,
London NW9 5HT, UK
www.thelancet.com Published online November 11, 2011
• …. Nair and colleagues present a rigorous
systematic review and meta-analysis of a
surprisingly weak evidence base. The investigators
assessed ..40 different studies between …with
different methodologies …Unsurprisingly in view of
the studies’ heterogeneity, estimates for global
hospitalisation and for overall mortality owing to
influenza in 2008 (28 000–111 500 deaths) in
children younger than 5 years need elaborate
statistical imputation…..

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