Author Contributions: Dr Baillargeon 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: Baillargeon, Giordano, Wu, Wells, Paar.
Acquisition of data: Baillargeon, Paar.
Analysis and interpretation of data: Baillargeon, Rich, Wu, Wells, Pollock, Paar.
Drafting of the manuscript: Baillargeon, Giordano, Wu, Wells.
Critical revision of the manuscript for important intellectual content: Baillargeon, Giordano, Rich, Pollock, Paar.
Statistical analysis: Baillargeon, Giordano, Wu, Pollock.
Obtained funding: Baillargeon, Giordano, Wu, Paar.
Administrative, technical, or material support: Baillargeon, Wells, Paar.
Study supervision: Baillargeon, Paar.
Financial Disclosures: Dr Giordano reports receiving research grants from Tibotech Therapeutics and Pfizer. Dr Paar reports serving on the speaker's panel for and serving on the Scientific Advisory Board of GlaxoSmithKline, Abbott Laboratories, Gilead Sciences, and Tibotech Therapeutics; serving on the speaker's panel for Virco Lab; and serving on the Scientific Advisory Board of Schering-Plough. No other authors reported financial disclosures.
Funding/Support: This study was supported by grant R03DA023870-02 from the National Institute on Drug Abuse. Dr Rich was supported by National Institute on Drug Abuse grant K24DA022112.
Role of the Sponsor: The funding organizations had no role in the design or conduct of the study; the collection, analysis, or interpretation of data; or the preparation, review, or approval of the manuscript.
Additional Contributions: We thank Leonard Pechacek (University of Texas Medical Branch [UTMB]) for editorial and writing assistance, Suzanne Graham and DeeAnn Novakosky (UTMB) for data management assistance, and Gwen Baillargeon, MS (UTMB), for statistical analysis assistance. None of these individuals received direct compensation for their contributions.