1. ¹Department of Urology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
2. ²Department of Urology, New York University School of Medicine, New York University Medical Center, New York, NY, USA
3. ³Department of Urology, Rush Medical College, Rush University, Chicago, IL, USA
4. ⁴Scott Department of Urology, Baylor College of Medicine, Houston, TX, USA
5. ⁵Sexual Health Team, Pfizer Inc, New York, NY, USA
6. ⁶Department of Urology, University Vita Salute San Raffaele, Milan, Italy
7. ⁷Department of Physical Medicine and Rehabilitation, Raymond Poincaré Hospital, Garches, France
8. ⁸Department of Urology, University of Western Ontario, London, ON, Canada

Correspondence: Dr AR McCullough, New York University School of Medicine, New York University Medical Center, 540 1st Avenue, Sirball Building, Suite 10U, New York, NY 10016, USA. E-mail: Andy.McCullough@nyumc.org

⁹R Siegel was an employee of Pfizer at the time of this research.

¹⁰The other members of the Study Group are Professor Robert Andrianne, Belgium; David Bell, Canada; Gregory Broderick, USA; Serge Carrier, Canada; Professor Beatrice Cuzin, France; Harry Jeoffrey Deeths, USA; Wayne Hellstrom, USA; Sender Herschorn, Canada; Ronald W Lewis, USA; Raymond C Rosen, USA; Ridwan Shabsigh, USA; Phillip Stricker, Australia.

Received 25 March 2007; Revised 23 May 2008; Accepted 23 May 2008; Published online 24 July 2008.

Abstract

Four weeks after bilateral nerve-sparing radical retropubic prostatectomy, men with normal erectile function before surgery were randomized to double-blind sildenafil (50 or 100 mg) or placebo nightly for 36 weeks, followed by an 8-week drug-free period before assessment of erectile function. Enrollment was prematurely ceased and only 76 men completed because, assuming a placebo response rate similar to the published literature (for example, 34% in meta-analysis), the 25% response at blinded interim review suggested a lack of treatment effect. On the contrary, spontaneous erectile function (a combined score of 8 for questions 3 and 4 of the International Index of Erectile Function and a positive response to 'Were erections good enough for satisfactory sexual activity?') occurred in only 4% of the placebo group (n=1 of 25) versus 27% (n=14 of 51, P=0.0156, Fisher's exact test) of the sildenafil group. Nightly sildenafil administration for 36 weeks after surgery markedly increased the return of normal spontaneous erections.