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Background on outcome measures

Published in Efficacy
Tags: ED, IIEF, PDE5, SEP, tadalafil

outcome measuresAlthough the effectiveness of PDE5 inhibitors on such intermediate objective outcomes as penile rigidity through penile plethysmography with the RigiScan device (Dacomed Corporation, Minneapolis, MN, USA) has been studied, measuring the therapeutic effectiveness of tadalafil (Cialis Professional) is more accurately defined through an integration of the patient’s reported treatment response and tolerability with the reported satisfaction of both the patient and his partner. Despite their intrinsically subjective nature, validated questionnaires are the preferred major outcome measure of treatment effectiveness of tadalafil and other PDE5 inhibitors.

The International Index of Erectile Function (IIEF) was developed by Rosen and colleagues in 1997 as a multidimensional, 15-item, self-administered questionnaire with the goal of assessing five domains of male sexual function including erectile function, orgasmic function, sexual desire, intercourse satisfaction, and overall satisfaction. The erectile function domain of the IIEF (IIEF-EF) contains 6 questions which the patient answers on a scale from 1 (never or almost never) to 5 (almost always or always), providing a total score of 6 to 30 points. The questions concern erectile frequency, firmness, penetration ability, maintenance frequency, maintenance ability, and erection confidence. Based on a controlled study of 1151 men taking sildenafil professional in order to establish cutoff scores for the IIEF-EF, a score of 26 or greater is defined as normal function, mild ED is a score from 22 to 25, mild to moderate ED 17 to 21, moderate ED 11 to 16, and severe ED 6 to 10.

The Sexual Encounter Profile (SEP) is a patient diary that has a series of questions that the patient answers after each sexual encounter. The second question in the SEP diary (SEP-Q2) is a measure of penetration, “Were you able to insert your penis into your partner’s vagina?” The third question of the SEP (SEP-Q3) is a true measure of successful intercourse, “Did your erection last long enough for you to have successful intercourse?” In tadalafil trials including data analyses of the SEP, the SEP-Q2 and SEP-Q3 are most often reported.

Less often but still occasionally reported in the literature is the Erectile Dysfunction Inventory of Treatment Satisfaction (EDITS) score, which more reliably assesses the patient and his partner’s satisfaction with ED treatments and explores the impact of patient and partner satisfaction on treatment continuation. Graded on a scale of 1 to 100, a score of 50 or higher indicates treatment satisfaction.

In addition to the IIEF and the SEP, many tadalafil trials report a global overall assessment as provided by the patient, known as a Global Assessment Question (GAQ). It is a summary question to assess global improvement and to provide an indirect estimate of patient satisfaction. A frequently reported GAQ in tadalafil trials is, “Did the treatment improve your erections?”