The Effect of Erectile Function on the Use of Phosphodiesterase-5 Inhibitors After Radical Prostatectomy in Japanese and U.S. Men

Published In: Urology, v. 71, no. 5, May 2008, p. 901-905

Posted on on January 01, 2008

by Shunichi Namiki, Lorna Kwan, Marjorie Kagawa-Singer, Yoichi Arai, Mark Litwin

OBJECTIVES: To compare patterns of phosphodiesterase-5 (PDE-5) inhibitor use between Japanese and U.S. men after radical prostatectomy. METHODS: A total of 168 Japanese men and 205 U.S. men with localized prostate cancer who were enrolled in studies of health-related quality-of-life outcomes participated in this study. Sexual function and bother were estimated with validated English and Japanese versions of the University of California-Los Angeles Prostate Cancer Index before and after treatment. Use of PDE-5 inhibitors was self-reported. RESULTS: During the 24 months after radical prostatectomy, 71.8% of the U.S. men and 10.1% of the Japanese men used PDE-5 inhibitors. Japanese users reported significantly better sexual function than did non-users before (41 versus 29, P = 0.028) and after (31 versus 9, P = 0.040) surgery. In contrast, the U.S. users reported significantly worse sexual function than did non-users before (59 versus 77, P <0.001) and after (33 versus 54, P <0.001) surgery. Postoperative sexual bother did not differ between users and non-users in either group. CONCLUSIONS: Japanese men were much less likely to use PDE-5 inhibitors than were U.S. men after radical prostatectomy, despite reporting worse sexual function scores. Cultural differences in patterns of PDE-5 inhibitor use after prostatectomy were evident.

This report is part of the RAND Corporation External publication series. Many RAND studies are published in peer-reviewed scholarly journals, as chapters in commercial books, or as documents published by other organizations.

Our mission to help improve policy and decisionmaking through research and analysis is enabled through our core values of quality and objectivity and our unwavering commitment to the highest level of integrity and ethical behavior. To help ensure our research and analysis are rigorous, objective, and nonpartisan, we subject our research publications to a robust and exacting quality-assurance process; avoid both the appearance and reality of financial and other conflicts of interest through staff training, project screening, and a policy of mandatory disclosure; and pursue transparency in our research engagements through our commitment to the open publication of our research findings and recommendations, disclosure of the source of funding of published research, and policies to ensure intellectual independence. For more information, visit

The RAND Corporation is a nonprofit institution that helps improve policy and decisionmaking through research and analysis. RAND's publications do not necessarily reflect the opinions of its research clients and sponsors.