Author Contributions: Dr Chang 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: Chang, Asch, Werner.
Acquisition of data: Chang.
Analysis and interpretation of data: Chang, Asch, Werner.
Drafting of the manuscript: Chang.
Critical revision of the manuscript for important intellectual content: Chang, Asch, Werner.
Statistical analysis: Chang, Werner.
Obtained funding: Chang.
Administrative, technical, or material support: Chang.
Study supervision: Chang.
Financial Disclosures: None reported.
Funding/Support: This work was supported by a Veterans Administration Health Services Research and Development Merit Award (IIR 06-096); the Robert Wood Johnson Foundation Physician Faculty Scholars Program; and a Veterans Administration Health Services Research and Development Career Development Award (to Dr Werner).
Role of the Sponsor: The funding organizations did not have any role in the design or conduct of the study; in the collection, management, analysis, or interpretation of the data; or in the preparation, review, or approval of the manuscript.
Disclaimer: The content of this article does not reflect the views of the Veterans Health Administration or of the US government.
Additional Contributions: We are extremely grateful to Ying Huang, MS (University of Pennsylvania, Philadelphia), and Anne Canamucio, MS (Philadelphia VA Medical Center, Philadelphia, Pennsylvania) for assistance with data programming. Ms Huang and Ms Canamucio were compensated for their contributions. We would also like to thank Theodore J. Iwashyna, MD, PhD (University of Michigan, Ann Arbor) for invaluable comments and suggestions. Dr Iwashyna did not receive compensation for his contribution to this article.