Study concept and design: Leventhal, Strong, Unger, Sussman, Audrain-McGovern.
Acquisition, analysis, or interpretation of data: Leventhal, Strong, Kirkpatrick, Unger, Riggs, Stone, Khoddam, Samet, Audrain-McGovern.
Drafting of the manuscript: Leventhal, Sussman, Stone, Khoddam, Samet, Audrain-McGovern.
Critical revision of the manuscript for important intellectual content: Strong, Kirkpatrick, Unger, Riggs, Samet, Audrain-McGovern.
Statistical analysis: Leventhal, Unger, Stone, Khoddam, Audrain-McGovern.
Obtained funding: Leventhal, Strong, Riggs, Audrain-McGovern.
Administrative, technical, or material support: Kirkpatrick, Sussman, Stone, Khoddam, Samet.
Study supervision: Leventhal, Kirkpatrick, Unger, Samet, Audrain-McGovern.
Conflict of Interest Disclosures: The authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest and none were reported.
Funding/Support: This research was supported by grants R01-DA033296 and P50-CA180905 from the National Institutes of Health.
Role of Funder/Sponsor: The National Institutes of Health 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.