Validation of the Dutch version of the International Index of Erectile Function (IIEF) in patients with erectile dysfunction and controls

Erectile dysfunction (ED) is defined as the inability to achieve or maintain an
erection sufficient for satisfactory sexual performance. Erectile dysfunction
is a fairly common disorder with a great impact on several aspects of quality
of life. In the Netherlands the prevalence of erectile dysfunction lies between
10 and 27% in men of all ages. Prevalence of ED rises with age. As a result of
the aging baby-boom population, prevalence of ED in western countries will
rise. It is estimated that in 2025 worldwide around 322 million men will have
ED to some extent. Treatment with PDE5-inhibitors is available for ED and
widely used.
ED can be a result of other conditions such as cardiovascular disease,
hypertension, hyperlipidaemia, diabetes mellitus and depression. Therefore ED
can be a possible marker for this conditions, which makes it important to
diagnose ED. ED can be diagnosed with different diagnostic instruments, the
simplest is with self-report questionnaires. The International Index of
Erectile Function (IIEF) is a 15-item self-administered questionnaire developed
by Rosen et al. as a brief and reliable measure of erectile function. The 15
items differentiate five domains of male sexual function (erectile function,
orgasmic function, sexual desire, intercourse satisfaction and overall
satisfaction).
The IIEF was developed for use by clinicians and researchers.
Different studies are done to validate the IIEF in Portuguese, Urdu, Malay and
German. It is remarkable that despite the fact that the IIEF is broadly used
both in clinical and research settings in the Netherlands, different versions
of the Dutch IIEF circulate. Moreover, a Dutch version was never validated.
Therefore this validation study will be performed. The present study is
designed to investigate the psychometric properties of the Dutch version of the
IIEF-15.

The present study is designed to validate the Dutch IIEF. The psychometric
properties of the Dutch version of the IIEF will be investigated.

We will perform an anonymous, case-control study. Patients with ED will be
recruited in the outpatient clinic of the department of urology of the LUMC.
Men coming with ED for explanation of a Nocturnal Penile Tumescence test (NPT)
will receive a questionnaire as part of the normal protocol to fill in during
this visit. At the end of this visit they will receive a second questionnaire,
which is an additional action, necessary for this study to measure test-retest
repeatability. Participants will be asked to fill in this second questionnaire
3 weeks after their visit and return it by mail in the distributed freepost
return envelope.
To constitute a control group, the male partners of sexually active women
consulting a urologist in our clinic will be asked to participate in the study
and will receive the patient information form. The urologist will provide the
questionnaire with an identification code.

Participants will fill in the questionnaire (IIEF-15) twice. This is a 15-item
self-administered questionnaire developed as a brief and reliable measure of
erectile function. This questionnaire contains questions about sexuality, an
intimate subject. The burden associated with participation however will be low
because participants voluntere to participate in the study. There are no risks
associated with participation.