Published Online: April 7, 2014. doi:10.1001/jama.2014.3700.
Conflict of Interest Disclosures: All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest and none were reported.
Additional Contributions: We would like to acknowledge Scott L. Greer, PhD (Department of Health Management and Policy, School of Public Health, University of Michigan), and Colleen Grogan, PhD (School of Social Service Administration, University of Chicago), for helpful comments on the draft manuscript. Neither of these persons received compensation for their contributions.
Correction: This article was corrected online on April 8, 2014, to clarify data.