Author Contributions: Mr Ding and Dr Liu had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.
Study concept and design: Ding, Liu.
Acquisition of data: Ding, Malik, Liu.
Analysis and interpretation of data: Ding, Song, Malik, Liu.
Drafting of the manuscript: Ding, Song, Malik, Liu.
Critical revision of the manuscript for important intellectual content: Ding, Song, Liu.
Statistical analysis: Ding, Song, Liu.
Obtained funding: Liu.
Administrative, technical, or material support: Liu.
Study supervision: Song, Liu.
Financial Disclosures: None reported.
Funding/Support: This study was funded in part by National Institutes of Health (NIH) grant DK066401-02; support for Mr Ding was provided by NIH grant CA009001-29.
Role of the Sponsor: The NIH 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.
Acknowledgment: We would like to thank Fang Tian, MD, MPH, Yeong-Liang Li, MD, and Emily Levitan, MS, Harvard School of Public Health, for their assistance on an early version of this project.