Author Contributions: Drs O’Connell and Wood 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: O’Connell, Wood, Braun.
Acquisition of data: O’Connell, Wood.
Analysis and interpretation of data: O’Connell, Wood, Wise, Lozier, Braun.
Drafting of the manuscript: O’Connell, Wood, Wise, Lozier.
Critical revision of the manuscript for important intellectual content: O’Connell, Wood, Wise, Lozier, Braun.
Statistical analysis: Wood.
Administrative, technical, or material support: O’Connell, Braun.
Study supervision: O’Connell, Wise, Braun.
Financial Disclosures: None reported.
Disclaimer: This report reflects work by the coauthors in their capacity as federal employees of the US Food and Drug Administration (FDA). They received no additional funding or support and have no conflicts of interest to report.
Acknowledgment: We thank FDA colleagues Jay Epstein, MD, Mary Foulkes, PhD, Charles Maplethorpe, MD, PhD, and Craig Zinderman, MD, MPH, for critical reading of the manuscript. There was no reimbursement for this work.