Author Contributions: Dr Stevens had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
Study concept and design: Stevens, Douketis.
Acquisition of data: Johnson, Stevens, Woller, Lake, Donadini.
Analysis and interpretation of data: Johnson, Stevens, Donadini, Cheng, Labarère, Douketis.
Drafting of the manuscript: Johnson, Stevens, Woller, Lake, Douketis.
Critical revision of the manuscript for important intellectual content: Johnson, Stevens, Woller, Donadini, Cheng, Labarère, Douketis.
Statistical analysis: Johnson, Donadini, Cheng.
Administrative, technical, or material support: Stevens, Woller, Douketis.
Study supervision: Stevens, Douketis.
Financial Disclosures: Dr Douketis reported receiving consulting fees from AGEN Biomedical, Janssen-Ortho, Boehringer-Ingelheim, Sanofi-Aventis, and AstraZeneca; and receiving speaker's fees from Pfizer, Leo Pharma, and Sanofi-Aventis. No other financial disclosures were reported.
Additional Contributions: We thank John Nord, MD, and Cheryl Pirozzi, MD (University of Utah, Salt Lake City) for performing the quality assessment review of included studies; C. Gregory Elliott, MD (Intermountain Medical Center, Murray, Utah) for literature review adjudication and manuscript review; and Shannon M. Bates, MD (McMaster University Medical Center, Hamilton, Ontario, Canada) for critical manuscript review. None of the above individuals received financial compensation for their work.