Author Contributions: Dr Werner 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: Werner, Goldman, Dudley.
Acquisition of data: Werner.
Analysis and interpretation of data: Werner, Goldman, Dudley.
Drafting of the manuscript: Werner, Dudley.
Critical revision of the manuscript for important intellectual content: Werner, Goldman, Dudley.
Statistical analysis: Werner.
Obtained funding: Werner, Dudley.
Administrative, technical, or material support: Werner.
Study supervision: Werner, Dudley.
Financial Disclosures: None reported.
Funding/Support: Dr Werner is supported in part by a Veterans Administration Health Services Research and Development Career Development Award. Dr Dudley's work on this project is supported by a Robert Wood Johnson Foundation Investigator Award in Health Policy and by the Agency for Healthcare Research and Quality.
Role of the Sponsors: The study sponsors had no role in the design and conduct of the study; the collection, management, analysis, and interpretation of the data; or the preparation, review, or approval of the manuscript.
Additional Contributions: We thank Janell Olah, MFA, for her research assistance and help in manuscript preparation. Ms Olah was employed by the University of Pennsylvania School of Medicine as a research assistant during this project.