Systematic Review Krit Pongpirul, MD, MPH. Johns Hopkins University

Why not just read a few papers?

Hierachy of Evidence Source: rahc/EBM/step2.htmlwww.library.uthscsa.edu

What is Systematic Review?

“A review of existing knowledge that uses explicit, scientific methods”

Steps Form team Question Search Selection Evaluation Synthesis

Question Types Y? X Y X Y

Formulating Question Population: Age, Race, Sex Setting: Community, Hospital, Outpatients Condition of interest Intervention (X) Outcome (Y)

Does drug decrease mortality in older persons with hypertension? X X Y Y

Y Y X X

Search Protocol Sources databases & hand searching Strategies Scope language, date, etc.

Where to search? PubMED, Cochrane Thai Index Medicus “Grey Literature”: theses, internal reports References of primary sources Unpublished sources

Reporting Bias Publication Bias Selective Outcome Reporting Language Bias Grey Literature Bias Impact Factor Bias Funding Bias Citation Bias

Selection Inclusion/exclusion criteria Review abstracts & titles Tracking

Databases 545 Hand Search 23 Retrieved 568 Duplicates 20 Abstract Review 548 Exclude 128 Article Review 400 Eligible Articles 200 Exclude 200

Evaluation Eligibility screen Assess quality of studies Abstraction of relevant data

Synthesis Qualitative Quantitative Grading of evidence