Published Online: November 4, 2013. doi:10.1001/jamainternmed.2013.11901.
Study concept and design: Ederhof.
Analysis and interpretation of data: Both authors.
Drafting of the manuscript: Both authors.
Critical revision of the manuscript for important intellectual content: Both authors.
Statistical analysis: Ederhof.
Administrative, technical, or material support: Ederhof.
Study supervision: Both authors.
Conflict of Interest Disclosures: None reported.
Funding/Support: Dr Chen is supported by a Career Development Grant Award (K08HS020671) from the Agency for Healthcare Research and Quality.
Role of the Sponsor: The funding source had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; and preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.
Previous Presentation: The study was presented at the AcademyHealth Annual Research Meeting; June 26, 2012; Orlando, Florida.
Additional Contributions: John Z. Ayanian, MD, MPP, provided comments on an earlier version of this manuscript. Mary Jane Giesey, BA, provided research assistance. She was compensated for her work.