Author Contributions: Dr Shekelle 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: Coker, Chan, Shekelle, Takata.
Acquisition of data: Coker, Chan, Newberry, Limbos, Takata.
Analysis and interpretation of data: Coker, Chan, Newberry, Limbos, Suttorp, Shekelle, Takata.
Drafting of the manuscript: Coker, Chan, Shekelle, Takata.
Critical revision of the manuscript for important intellectual content: Coker, Chan, Newberry, Limbos, Suttorp, Shekelle, Takata.
Statistical analysis: Chan, Suttorp.
Obtained funding: Shekelle.
Administrative, technical, or material support: Newberry.
Study supervision: Shekelle, Takata.
Financial Disclosures: Dr Takata reported owning 100 shares of Pfizer stock, which he sold at the start of the study. No other authors reported disclosures.
Funding/Support: This article is based on research conducted by the Southern California Evidence-based Practice Center (EPC) under contract with the Agency for Healthcare Research and Quality (AHRQ) (contract 290-2007-10056). This work was commissioned by AHRQ as an update to an earlier report and in support of the update of practice guidelines.
Role of the Sponsor: AHRQ had a role, through its sponsorship of the EPC program, in the general methods of EPC systematic reviews and in development of the key questions for each review. However, AHRQ had no role in the specific conduct of the review; in the collection, management, analysis, and interpretation of the data; or in the preparation, review, or approval of the manuscript.
Disclaimer: The authors of this article are responsible for its contents. No statement in this article should be construed as an official position of AHRQ or the US Department of Health and Human Services.
Additional Contributions: Roberta Shanman, MLS (RAND Library), conducted the literature searches. Martha Timmer, MS (EPC, RAND Health, Santa Monica), provided scientific programming and data entry support for the evidence report prepared for AHRQ. Aneesa Motala, BA, and Breanne Johnsen, BS (EPC, RAND Health), contributed to the evidence report and the manuscript. As RAND employees, these individuals were compensated from the EPC contract for this study but none received additional compensation for their contributions.