Volume 7: No. 6, November 2010

SYSTEMATIC REVIEW
Quality of Systematic Reviews of Observational Nontherapeutic Studies

This flow chart shows 3 boxes. The top box reads

Total references — 1,053

• Medline via PubMed — 904
• Related publications — 14
• WorldCat — 2
• Scirus — 28
• Manual search — 70
• Guidelines, textbooks, consensus statements — 23
• Published by the authors — 11
• Cochrane Library — 1

It is connected by a vertical line to 2 additional boxes. The left box reads

Included studies — 397

• Systematic reviews for the present article — 145
• Tools (scales and checklists) — 96
• Working groups — 13
• Methodologic studies about bias in observational research — 143

The right box reads

Excluded studies — 656

• Ethical guidelines — 3
• Reviews — 23
• Centers for Disease Control and Prevention study — 4
• Related to interventions — 209
• Related to diagnostic studies — 54
• Not relevant to research questions — 363

Figure. Study flow to identify systematic reviews of observational studies, scales and checklists for planned, formal internal quality evaluation, and studies about bias in observational research.

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The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention.

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