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Placebo and nocebo effects in randomized trials with phosphodiesteraze type 5 inhibitors
Article published in Urologia Polska 2005/58/2.

authors

Jakub Dobruch, Andrzej Borówka, Artur A. Antoniewicz
Oddział Urologii Międzyleskiego Szpitala Specjalistycznego w Warszawie
Ordynator oddziału: prof. dr hab. Andrzej Borówka

keywords

erectile dysfunction, phosphodiesteraze type 5 inhibitors, nocebo, placebo

summary

introduction and objectives
Efficacy of phosphodiesteraze type 5 inhibitors in the treatment of erectile dysfunction has been proved in many randomized, placebo controlled trials. The purpose of the study was to evaluate the role of placebo and nocebo effects in randomized trials concerning treatment of erectile dysfunction with phosphodiesteraze type 5 inhibitors.
material and methods
Results of randomized, placebo controlled trials concerning efficacy and safety of phosphodiesteraze type 5 inhibitors (sildenafil, vardenafil and tadalafil) in the treatment of erectile dysfunction were analyzed. The placebo effect was estimated basing on the changes of International Index of Erectile Function (IIEF) and Global Assessment Questions (GAQ) symptoms scores. Placebo effect was presented as percent change of mentioned above indexes comparing final and initial values. Nature and frequency of observed adverse events and percentage of men who discontinued the study were also evaluated.
results
Erectile function was improved in the placebo groups. Mean IIEF-5 questions 3 and 4 increased even by 50% and 44% respectively. The percentage of men who claimed that erectile function improved reached 37%. 0-81% of patients within the placebo groups discontinued the study. Adverse events were the reason of discontinuation in 0% to 2.6% cases.
conclusions
The placebo effect was observed in each study however its intensity varied among studies. It was less evident in men with proved organic etiology of erectile dysfunction.

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correspondence

Jakub Dobruch
Międzyleski Szpital Specjalistyczny
ul. Bursztynowa 2
04-749 Warszawa
tel. 0 503072230
kubadobr@amwaw.edu.pl