Author Contributions: Dr MacLean 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: MacLean, Khanna, Issa, Garland, Morton.
Acquisition of data: MacLean, Mojica, Khanna, Issa, Traina, Garland.
Analysis and interpretation of data: MacLean, Newberry, Khanna, Suttorp, Lim, Traina, Hilton, Garland, Morton.
Drafting of the manuscript: MacLean, Newberry, Lim, Traina, Hilton, Garland, Morton.
Critical revision of the manuscript for important intellectual content: MacLean, Newberry, Mojica, Khanna, Issa, Suttorp, Morton.
Statistical analysis: Issa, Suttorp, Morton.
Obtained funding: Morton.
Administrative, technical, or material support: MacLean, Newberry, Mojica, Issa, Traina, Hilton, Garland.
Study supervision: MacLean, Garland.
Data management: Hilton.
Financial Disclosures: None reported.
Funding/Support: Supported by the Agency for Healthcare Research and Quality (AHRQ) contract 290-02-0003. Dr MacLean is a Veterans Health Administration Health Services Research and Career Development Awardee.
Role of the Sponsor: The funding source had no role in the conduct of the study, collection of data, management, analysis, interpretation of the data or preparation of the manuscript. AHRQ did review and approve the manuscript.
Disclaimer: This research was conducted through the AHRQ Evidence Based-Practice Center program and as such followed AHRQ's guidelines for the design, collection, and presentation of data for evidence reports.
Acknowledgment: We thank Paul Shekelle, MD, PhD, of RAND Health and the Greater Los Angeles Veterans Health Care System, for his review of the manuscript.