Author Contributions: Dr Vinck 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: Vinck, Pham.
Acquisition of data: Vinck.
Analysis and interpretation of data: Vinck, Pham.
Drafting of the manuscript: Vinck, Pham.
Critical revision of the manuscript for important intellectual content: Vinck, Pham.
Statistical analysis: Vinck, Pham.
Obtained funding: Vinck, Pham.
Study supervision: Vinck, Pham.
Financial Disclosures: None reported.
Funding/Support: The work was supported by grants from the John D. and Catherine T. MacArthur Foundation, Chicago, Illinois, and Humanity United, Redwood City, California.
Role of the Sponsor: The funding organizations had no role in the design and conduct of the study; in the collection, analysis, and interpretation of the data; or in the preparation, review, or approval of the manuscript.
Additional Contributions: The study was part of the Vulnerable Populations Initiative at University of California, Berkeley. We thank the respondents, interviewers, and partners in the field for their support. Neil Hendrick, BA, contributed to field supervision. Roger Sherwin, MD, Tulane University; Jennie Sherwin, BA; and Alexander Truong, MD, MPH, Johns Hopkins University, provided invaluable comments on the manuscript. Mr Hendrick was paid to assist with field work. Dr Sherwin, Ms Sherwin, and Dr Truong did not receive compensation for their contributions.