Author Contributions: Dr Nurnberg and 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: Nurnberg, Hensley, Paine.
Acquisition of data: Nurnberg, Hensley, Heiman, Croft, Debattista.
Analysis and interpretation of data: Nurnberg, Hensley, Paine.
Drafting of the manuscript: Nurnberg, Hensley, Heiman, Paine.
Critical revision of the manuscript for important intellectual content: Nurnberg, Hensley, Heiman, Croft, Debattista, Paine.
Statistical analysis: Nurnberg, Paine.
Obtained funding: Nurnberg.
Administrative, technical, or material support: Nurnberg, Hensley, Heiman, Croft, Debattista.
Study supervision: Nurnberg, Hensley.
Financial Disclosures: Dr Nurnberg reports having received research support from Bristol-Myers Squibb Co, Eli Lilly & Co, Lilly-Icos, Pfizer Inc, Wyeth, and Bayer; that he is or has been a paid consultant for Wyeth, Pfizer, Eli Lilly & Co, GlaxoSmithKline, and Abbott Laboratories; and that he is or has also been on the speakers bureau for Pfizer, Wyeth, GlaxoSmithKline, Abbott Laboratories, Eli Lilly & Co, Lilly-Icos, and Bayer. Dr Hensley reports having received research and grant support from Forest Pharmaceuticals, Novartis, Pfizer Inc, and Roche Pharmaceuticals; that she is a paid consultant for Forest Pharmaceuticals; and that she has served on the speakers bureau for Forest Pharmaceuticals, Takeda, Janssen Pharmaceuticals, and Wyeth. Dr Croft reports having received honoraria and/or research support from Boehringer-Ingelheim, Bristol-Meyers Squibb, Cephalon, Forest, GlaxoSmithKlein, Lilly, Merck, Organon, Pfizer, and Sanofi-Aventis. Dr Debattista reports having received honoraria and/or research support from Pfizer, Corcept, Pritzker Foundation, GlaxoSmithKline, Wyeth, Lilly, Cephalon, Pfizer, Cyberonics, Neuronetics, Novaritis, Astra Zeneca, Forest, CNS Response, Boerhinger; reports having been a speaker or consultant for Lilly, GlaxoSmithKline, Pfizer, Cephalon, Wyeth, Bristol-Meyers Squibb, Cyberonics, Corcept, Forest and reports being a stock holder of Corcept Therapeutics. Dr Heiman reports having received research support from Pfizer Inc, Bayer Pharmaceutical, and Zestra Laboratories. Ms Paine has no financial conflicts.
Funding/Support: This study was supported by an independent investigator-initiated grant from Pfizer Inc, New York, New York. Pfizer Inc provided sildenafil and matching placebo.
Role of the Sponsor: Pfizer had no other role in the design and conduct of the study; collection, management, analysis, interpretation of the data, and preparation, review, or approval of the manuscript.
Participating Sites: University of New Mexico, Albuquerque; University of Washington, Seattle; Stanford University, Palo Alto, California; University of Oklahoma, Tulsa; Robert Woods Johnson University of Medicine and Dentistry, Piscataway, New Jersey; Croft Group Research Center, San Antonio, Texas; and Massachusetts General Hospital, Boston.
Independent Statistical Analysis: The statistical analysis was performed by Dr Nurnberg and Ms Paine, an independent statistician at the University of New Mexico; both are full time employees of the University of New Mexico who receive their compensation and funding through that institution. No other compensation or funding was received for conducting the analyses.