Published Online: March 16, 2015. doi:10.1001/jamainternmed.2015.0153.
Study concept and design: Wang, Grey.
Acquisition, analysis, or interpretation of data: All authors.
Drafting of the manuscript: Grey.
Critical revision of the manuscript for important intellectual content: Wang. Gamble.
Statistical analysis: Wang, Gamble.
Conflict of Interest Disclosures: None reported.
Funding/Support: Funding for this study was provided by the Health Research Council of New Zealand and the University of Auckland.
Role of the Funder/Sponsor: The funding sources had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.