Prevalence of erectile dysfunction among middle-aged men in a metropolitan area in Germany

Abstract

The comparison of results of previous studies on the prevalence of erectile dysfunction is hampered due to differences in study design and research instruments including definitions used. The aim of the study was to determine the prevalence of erectile dysfunction/erectile disorder (ED) using different definitions. An epidemiological cross-sectional study was conducted between May and November 2002 in Berlin, Germany. A total of 6000 men between 40 and 79 years of age were randomly selected by the Berlin Office of Vital Statistics and were sent a questionnaire by mail. The prevalence of ED was determined using five different methods. A total of 1915 questionnaires were eligible for analysis. The five different definitions yielded age-adjusted ED prevalence rates between 18 and 48%. Age was strongly correlated with all five definitions (P<0.001). These results indicate the need for standardized criteria when conducting future studies on ED and may aid in designing public health and clinical management strategies.

Full text

ORIGINAL ARTICLE
Prevalence of erectile dysfunction among middle-aged men
in a metropolitan area in Germany
H Englert
1
, G Schaefer
2
, S Roll
1
, C Ahlers
2
, K Beier
2
and S Willich
1
1
Charite
´
-University Medical Center, Institute of Social Medicine, Epidemiology and Health Economics, Berlin, Germany
and
2
Charite
´
-University Medical Center, Institute of Sexology and Sexual Medicine, Berlin, Germany
The comparison of results of previous studies on the prevalence of erectile dysfunction is hampered
due to differences in study design and research instruments including definitions used. The aim of
the study was to determine the prevalence of erectile dysfunction/erectile disorder (ED) using
different definitions.An epidemiological cross-sectional study was conducted between May and
November 2002 in Berlin, Germany. A total of 6000 men between 40 and 79 years of age were
randomly selected by the Berlin Office of Vital Statistics and were sent a questionnaire by mail. The
prevalence of ED was determined using five different methods. A total of 1915 questionnaires were
eligible for analysis. The five different definitions yielded age-adjusted ED prevalence rates between
18 and 48%. Age was strongly correlated with all five definitions (Po0.001). These results indicate
the need for standardized criteria when conducting future studies on ED and may aid in designing
public health and clinical management strategies.
International Journal of Impotence Research (2007) 19, 183–188. doi:10.1038/sj.ijir.3901510;
published online 3 August 2006
Keywords: erectile dysfunction; prevalence rates; men and health; epidemiology; public health;
age
Introduction
Erectile dysfunction is defined as the inability to
achieve or maintain an erection sufficient for
satisfactory sexual function,
1
whereas erectile dis-
order (ED) is the recurrent inability to achieve or
maintain an adequate erection until completion of
sexual activity while simultaneously causing dis-
tress and interpersonal problems.
2
Despite the fact
that investigating erectile dysfunction/ED is diffi-
cult due to the nature of the topic, the amount of
epidemiological research has increased over the past
five decades. However, the prevalence rates found
in these studies have varied widely.
3–10
The first
epidemiological study of male sexual behavior was
published in 1948 by Kinsey et al.
11
They recruited
a total of 15 781 men up to 80 years of age and found
a prevalence of erectile dysfunction ranging from
o1% for young men to 80% in the uppermost age
group. The Massachusetts Male Aging Study, a
community-based observational study of a random
sample of men between 40 and 70 years of age,
showed a 52% overall prevalence rate for impo-
tence.
12
The German ‘Cologne Male Study’
(n ¼ 4489) found an overall prevalence of erectile
dysfunction of 19%, which increased dramatically
with age: while the prevalence in men aged 30–39
years was 2%, it was 53% in men aged 70–79
years.
13
A recent study in Finland (n ¼ 3787)
reported an overall prevalence of 77% in men
between 50 and 75 years of age.
14
In other studies,
prevalence rates of erectile dysfunction have ranged
from 61% in Belgium, 69% in Italy to about 80%
in Japan.
15–18
The variability in various aspects of
previous investigations such as ED definitions,
questionnaire used, study design, age distribution,
study population and sample size make a compar-
ison of ED prevalence rates difficult. Quantitative
data on the effect of different definitions of ED on
the prevalence are lacking, because precise informa-
tion on the used definition and questionnaire is
often absent. Boer et al.
19
quantified the effect of
using different questionnaires for ED on the pre-
valence estimates and conducted a difference of
16.8% between International Index of Erectile
Function (IIEF), WHO, KEED and one question.
Received 7 February 2006; revised 5 May 2006; accepted
29 June 2006; published online 3 August 2006
Correspondence: Dr H Englert, Charite
´
-University Medical
Center, Institute of Social Medicine, Epidemiology and
Health Economics, Luisenstr 57, Berlin 10117, Germany.
E-mail: heike.englert@charite.de
International Journal of Impotence Research (2007) 19, 183–188
&
2007 Nature Publishing Group All rights reserved 0955-9930/07 $30.00
www.nature.com/ijir

In addition, knowing the prevalence of erectile
dysfunction does not provide any information about
the distress experienced by affected patients; nor
does it give any insight into the clinical relevance of
the condition.
In a meta-analysis, Simon and Cary
20
observed
that previous studies had not taken the DSM-IV
criteria into account, which resulted in a lack of
prevalence data on ED.
Therefore, the aim of the present study was to
determine the prevalence of erectile dysfunction/ED
using five different definitions.
Methods
Study design and subjects
This epidemiological cross-sectional study, called
the Berlin Male Study, was conducted in Berlin,
Germany between May and November 2002. The
sample was selected as follows: out of all 680 000
Berlin men between the ages of 40 and 79, 16 210
men were selected randomly. This resulted in the
following distribution, which was representative
(with respect to age) of the general male population
in the city: 40–49 years of age, n ¼ 5000 (31%); 50–
59 years of age, n ¼ 4685 (29%); 60–69 years of age,
n ¼ 4606 (28%); and 70–79 years of age, n ¼ 1919
(12%). From each of these four age groups, 1500
men were selected randomly to guarantee a mini-
mum sample size in each age group. The total
sample (n ¼ 6000) was then contacted by standard
mail. Nonresponders were contacted by standard
mail a second time and asked to return the
questionnaire. The addresses were provided by the
Berlin Office of Vital Statistics. The ethics commit-
tee of the Charite
´
University Medical Center, Berlin
granted approval for the study, which was con-
ducted according to the stipulation of the German
Data Protection Act.
Research instrument
The developed questionnaire was tested in a pilot
phase and modified for improved feasibility, clarity
and understandability on a group of 30 male
patients above 30 years of age, who had presented
with urological conditions. This research instru-
ment consists of six sections: (1) socio-demo-
graphics (including nationality, age, marital status,
highest level of education, current occupational
status), (2) health history (including medical condi-
tions, medications, operations), (3) health status
(EuroQol Visual Analog Scale), (4) lifestyle vari-
ables, quality of life (SF-12), (5) satisfaction with
current state of relationship and (6) sexuality
(including: sexual orientation, relationship status,
frequency of sexual activity, importance of and
satisfaction with sex life, erectile function).
Every section starts with a brief instruction how to
answer the questions. The sexuality section addi-
tionally begins with the definitions of sexual
intercourse, sexual activity (including sexual inter-
course, caresses and masturbation) and sexual
stimulation (including all stimulating situations
with the partner).
The presence of ED was determined using five
different definitions. The first three definitions used
the erectile function (EF) domain. The EF domain is
comprised of a six-item checklist (five items of the
IIEF, a standard sexual function questionnaire that
includes questions about the ability to achieve and
maintain erections to the completion of sexual
intercourse and one item about the confidence to
achieve and maintain an erection) consistent with
NIH guidelines for the definition of erectile dysfunc-
tion, concerning erectile function over the past 4
weeks.
1
The EF domain demonstrates favorable
statistical properties as a diagnostic tool not only
in distinguishing between men without erectile
dysfunction (EF scores between 26 and 30) and with
erectile dysfunction (EF scores between 1 and 25),
but also in categorizing erectile dysfunction into
four levels of severity. An EF score between 25 and
22 indicates ‘mild’ severity, between 21 and 17 ‘mild
to moderate’ severity, and between 16 and 11
‘moderate’ severity of erectile dysfunction.
21,22
The
categorization of the fourth level ‘severe’ erectile
dysfunction is dependent on whether the sexually
inactive men are included in the analysis or not.
When sexually inactive men are included, an EF
score of 10–1 leads to a rating of ‘severe’ erectile
dysfunction – and when sexually inactive men are
not included, a rating of ‘severe’ erectile dysfunction
is reached by an EF score between 10 and 6.
23
Prevalence rates based on the EF domain were
assessed in this study according to the following
three definitions:
Definition 1: includes all men, whether sexually
active (over the last 4 weeks) or not,
and is thus referred to as ED ‘EF all’.
Definition 2: includes only sexually active men
(over the last 4 weeks), and is thus
referred to as ED ‘EF active’.
Definition 3: includes all sexually active men
(over the last 4 weeks) as well as
those sexually inactive men (over
the last 4 weeks) who have low
confidence in their ability to achieve
and/or maintain an erection, and is
thus referred to as ED ‘EF confi-
dence’. (‘Low’ summarizes the cate-
gories ‘moderate’, ‘low’ and ‘very
low’ confidence). Men were classi-
fied as sexually inactive if they
reported ‘no sexual activity’ on all
five questions of the EF domain for
Prevalence of erectile dysfunction and ED in men
H Englert et al
184
International Journal of Impotence Research

which this answer was possible. The
sixth question of the EF domain
addressed the participants’ confi-
dence in their ability to achieve
and/or maintain an erection and
did not offer the option ‘no sexual
activity’. To be classified as suffering
from ‘severe ED’, a participant’s EF
score had to lie between 1 and 10
according to the ED ‘EF confidence’
criteria.
The fourth approach was used to determine
prevalence rates based on participant self-assessment:
Definition 4: The participants’ answer to the one-
item question ‘Do you think you have
erectile dysfunction?’ was used to
determine the prevalence of the con-
dition. As the prevalence rates deter-
mined here rely solely on the
participant self-assessment, this group
is referred to as ED ‘subjective’.
The fifth approach was used to determine the
prevalence rates for ED:
Definition 5: ED ‘DSM-IV’ was determined according
to the Diagnostic and Statistical Manual
of Mental Disorder criteria (DSM-IV).
When determining the prevalence of ED
according to DSM-IV, both the lack of
erectile function (criterion A) and the
emotional distress associated with it
(criterion B) must be established before
adiagnosiscanbemade.
24
Criterion A
was met when at least one of the six
items addressing erectile function was
answered with ‘sometimes’ or less.
Criterion B was met when the presence
of suffering was confirmed, or one of
the six items addressing the frequency
and severity of suffering was answered
with ‘seldom’/‘low’ or more. Indivi-
duals were only assigned to the category
ED in cases where both criteria A and B
were met.
In addition, participants with self-reported ED
were asked to state whether they had at any time
sought treatment. They were given various answers
to choose from: ‘No, I’m not interested’, ‘No, but I
am interested’, ‘Yes, medical’, ‘Yes, psychological’,
‘Yes, alternative’, ‘Yes, with spouse’, ‘Yes, with
success’, and ‘Yes, but I cancelled treatment’.
Data management and statistical analyses
The completed questionnaires were scanned with a
high-speed scanner. To ensure reliability and qual-
ity, all scanned data were checked for plausibility,
verified manually if necessary, and transferred to an
SPSS file. The statistical analyses were performed
with SAS version 8.2 (used for logistic regression)
and SPSS version 11.0 (used for the remaining
analyses). Overall age-adjusted prevalence rates
were weighed according to the general population.
For univariable analyses t-test was used for contin-
uous variables and w
2
-test for categorical variables.
Statistical significance was stated at the 0.05-level.
Results
Of 6000 mailed questionnaires, 1927 were returned.
A total of n ¼ 1915 of these were eligible for analysis,
12 having been excluded due to a large amount of
missing data. Thus, the overall response rate was
32%. However, not all 1915 men answered every
question, and not all questionnaires were included
in each of the five approaches. Therefore, the sample
sizes for the various variables varied from n ¼ 1915
(for ‘nationality’) to n ¼ 1233 (for ED ‘EF active’
approach). Table 1 shows the socio-demographic
profile of the sample.
With regard to medical history, 75% reported one
or more conditions (Table 2). The five different
definitions yielded the following overall age-ad-
justed prevalence rates: 48% (ED ‘EF all’), 31% (ED
‘EF active’), 44% (ED ‘EF confidence’), 24% (ED
‘subjective’) and 18% (ED ‘DSM-IV’). Our findings
regarding the prevalence of erectile dysfunction/ED
by age groups are shown in Figure 1. In the ED ‘EF
all’ definition, prevalence ranged from 28% in the
lowest age group to 82% in the uppermost age
group. In the ED ‘EF active’ definition, however, the
prevalence of erectile dysfunction range from only
17 to 63% depending on the age group. The rates in
the ED ‘EF confidence’ definition ranged from 22%
for the lowest to 81% for the uppermost age group.
The lowest prevalence for each age group was found
in the ED ‘DSM-IV’ (between 7 and 26%) and the
ED ‘subjective’ definition (between 9 and 51%).
Important to note, however, is that the rates increased
from age group to age group, regardless of the
approach used to determine the prevalence rate.
Table 3 shows the 490 men who were sexually
inactive over the past 4 weeks and, thus, excluded
from the ED ‘EF active’ definition. Out of these 490
men, 125 (24%) reported their confidence in
achieving and/or maintaining an erection to be high
(62% in the lowest age group, 45% in the second,
25% in the third and 6% in the uppermost age
group). The remaining 365 men (74%) reported their
confidence in achieving and/or maintaining an
erection to be low.
The distribution of the severity levels based on the
ED ‘EF confidence’ approach is shown in Table 4.
The percentage of ‘severe ED’ cases increased from
the lowest to the uppermost age group from 16 to
61%, whereas the amount of ‘mild ED’ cases
decreased from 51 to 18%.
Prevalence of erectile dysfunction and ED in men
H Englert et al
185
International Journal of Impotence Research

Among those who self-reported having erectile
dysfunction/ED, 39% were not interested in treat-
ment, whereas 26% were interested in treatment
and 35% had obtained treatment previously.
Discussion
In the Berlin Male study the prevalence rates were
assessed using five different definitions, yielding
overall prevalence rates between 18 and 48%.
Prevalence rates of erectile dysfunction/ED differed
widely depending on the definition used. The main
difference between the three definitions using the
well established and validated EF domain.
21–23
was
the inclusion of the subgroup men who had been
Table 1 Socio-demographic characteristics of the study popula-
tion
Variables n
a
%
Nationality (n ¼ 1915)
German 1878 98
Other 37 2
Age categories (n ¼ 1905)
40–49 473 25
50–59 474 25
60–69 478 25
70–79 480 25
Current marital status (n ¼ 1892)
Single 209 11
Married 1287 68
Widowed 85 5
Divorced 311 16
Partnership status (n ¼ 1746)
No partner 271 15
Female partner 1446 83
Male partner 29 2
Sexual orientation (n ¼ 1888)
Heterosexual 1812 96
Homo/bisexual 76 4
Current occupational status (n ¼ 1608)
Employed 737 46
Not employed 871 54
Unemployed 180 18
Retired 634 64
Sick leave 179 18
School/training 4 0.2
Highest level of education (n ¼ 1781)
No graduation 45 3
Graduated 9th grade 554 31
Graduated 10th grade 401 22
Graduated 13th grade (high school) 211 12
University degree 570 32
a
Total ‘n’ vary due to missing information.
Table 2 Prevalence of various medical conditions
Conditions (N ¼ 1915)
a
n %
No condition 486 25
High blood pressure 536 28
Vertebral disease 431 23
Hypercholesterolemia 375 20
Heart disease 224 12
Prostate disease 216 11
Diabetes mellitus 152 8
Depression 87 5
Tumor 75 4
Stroke 60 3
a
Multiple answers were possible.
Figure 1 Prevalence of erectile dysfunction/ED according to
various approaches and age categories (in percent). ED ‘EF all’:
based on the erectile function (EF) domain (including all men).
ED ‘EF confidence’: based on the EF domain (including only
sexually active men plus inactive men with a low confidence
of achieving and maintaining an erection). ED ‘EF active’: based
on the EF domain including only sexually active men. ED
‘subjective’: based on participant’s subjective judgment on the
presence of ED. ED ‘DSM-IV’: as defined in the Diagnostic and
Statistical Manual of Mental Disorders-IV (DSM-IV). Confidence
intervals of the proportions.
Table 3 Confidence in achieving and maintaining an erection
among those who reported no sexual activity in the past 4 weeks
Age categories
Confidence
(n ¼ 490)
40–49%
(n ¼ 57)
50–59%
(n ¼ 95)
60–69%
(n ¼ 139)
70–79%
(n ¼ 199)
Very high
a
35 13 6 1
High
a
27 32 19 5
Moderate
b
26 25 25 20
Low
b
5161319
Very low
b
7143755
a
Very high and high were summarized to high and excluded in
the ED ‘EF confidence’ approach.
b
Moderate, low and very low were summarized to low and
included in the ED ‘EF confidence’ approach.
Prevalence of erectile dysfunction and ED in men
H Englert et al
186
International Journal of Impotence Research

‘sexually inactive’ during the previous 4 weeks.
Simply excluding these men from the analysis
resulted in a decrease in overall prevalence from
48% (ED ‘EF all’) to 31% (ED ‘EF active’). Doing so,
however, is clearly problematic, as clinical experi-
ence has shown that sexual inactivity is often a
consequence of low confidence in achieving and/or
maintaining an erection due to having experienced
a dysfunctional erection in the past.
25
In contrast,
sexually inactive men with high confidence are
presumably inactive for reasons unrelated to sexual
functioning.
23
In order to address this subtle
distinction, data from these 490 sexually inactive
men were analyzed with regard to their confidence
in achieving and/or maintaining an erection. The
results showed that only 26% were highly positive,
while 74% had only low confidence in achieving
and maintaining an erection. Boer et al.
25
stated that
men with erectile dysfunction were less content
with their sexual life and had less confidence in
sexual performance. With this in mind, the third
definition (ED ‘EF confidence’) was designed to
categorize sexually inactive men with low confi-
dence as eligible for analysis, whereas sexually
inactive men with high confidence in achieving
and maintaining an erection were excluded. Report-
ing low confidence justifies the inclusion of respon-
ders when determining the prevalence of erectile
dysfunction, as their inactivity may well be due to
having experienced a dysfunctional erection at some
point in the past. While prevalence following the ED
‘EF all’ definition might be overestimated, preva-
lence rates following the ED ‘EF active’ method
might be underestimated. A fourth method involved
self-assessment of ED (‘ED subjective’). Compared to
the results of all three EF domain approaches, ED
prevalence may be underreported in self-assess-
ment. This finding is consistent with other stu-
dies.
10
Hence, in the authors’ view, the ED ‘EF
confidence’ approach will yield the most realistic
prevalence rates of erectile dysfunction.
However, none of the studies mentioned above
considered DSM-IV criteria when determining pre-
valence of ED. Neither the prevalence rate of erectile
dysfunction reported in this study using the three
different definitions based on the EF domain, nor
the self-reported prevalence rates allow us to
evaluate the clinical relevance of the condition. As
erectile dysfunction is not a life-threatening disease,
the most important reason for possible treatment
might be emotional distress or interpersonal pro-
blems. Research projects investigating the impact of
different chronic diseases on sexuality and partner-
ship based on the DSM-IV criteria clearly reveal that
sexual dysfunctions are not necessarily associated
with emotional distress.
26–28
Thus, using a fifth definition based on DSM-IV
criteria, men with erectile dysfunction associated
with emotional distress (measured over the last 6
months) were identified. This approach allows us to
differentiate between erectile dysfunction (without
consideration of emotional distress) and ED (with
consideration of emotional burden).
29
Following the
DSM-IV criteria, the age-adjusted total was only
18%. The data obtained with the different methods
show a high proportion of men with erectile
dysfunction but without distress and thus without
clinical relevance. This may explain the varying
attitudes towards treatment between men diagnosed
using the EF domain-based approach and those
diagnosed with the DSM-IV-based approach. From a
clinical point of view, it seems essential to incorpo-
rate in a standardized instrument the question of
whether erectile dysfunction is associated with
emotional distress. Further discussion is required
about how long the observation period should be
(e.g. 1, 3 or 6 months) and how to measure emotional
distress in an effective and reliable fashion.
Limitations
Some general weaknesses of the study should be
pointed out. The reponse rate was only 32%. To
evaluate the different categories of erectile dysfunc-
tion and ED, the questionnaire was quite long,
thereby perhaps reducing the response rate. Boer
et al.
19
stated that the number of questions appears
to affect the response rate. Therefore, we suggest the
use of shorter instruments for further studies. In
addition, the sensitive nature of the topics in general
may have reduced participation rates. As the
response rate in each age categories was similar
(approximately. 25% in each age group), it was
possible to adjust prevalence rates in each category
for overall prevalence rates. A selection bias cannot
be excluded and no statement can be made regard-
ing the applicability of our data to the German
population and for other populations of the world.
As the study was conducted anonymously, parti-
cipants who did not answer every question could
not be contacted again. Thus, it was impossible to
reduce the amount of missing data. As data was
collected solely via self-completed questionnaire,
the assessment was limited to self-report and, as a
consequence, may have led to some biased results.
Table 4 Severity of ED in age categories (in percent, based on the
ED ‘EF confidence’ definition)
Age categories
Severity 40–49 (%) 50–59 (%) 60–69 (%) 70–79 (%)
Mild 51 44 33 18
Mild–moderate 23 17 16 13
Moderate 10 11 7 8
Severe 16 28 44 61
Prevalence of erectile dysfunction and ED in men
H Englert et al
187
International Journal of Impotence Research

Conclusions
In this study, we focus on the marked influence of
different definitions on the prevalence rates. As one
data set produced five different prevalence rates
of erectile dysfunction/ED, depending on the defini-
tion used, it is important to agree upon a uniform
way of assessing erectile dysfunction and ED to
make prevalence rates comparable across studies.
There is a need for a standardized concise ques-
tionnaire including the definition of sexual activity,
the timeline investigated (4 weeks or 6 months), the
self-report question, the length of the questionnaire
and the impact of distress. Comparability of pub-
lished prevalence rates will be important to assess
the epidemiological magnitude of the disorder as
well as for designing adequate therapeutic and
public health strategies.
Acknowledgments
This study was supported by grants from Bayer Vital
GmbH and GlaxoSmithKline, Germany.
None of the authors had competing interests.
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