Over the last 20 years, a number of studies that have examined the incidence of erectile dysfunction (ED) have been conducted worldwide. The results are sometimes very different. That’s not surprising though. The determination of the frequency of erectile dysfunction is sometimes much more complicated than, for example, the determination of the number of motor vehicles per capita of the population.
The following factors strongly influence the outcome of such a study:
- The study’s definition of erectile dysfunction
- The type of data collection (e.g. interview or questionnaire)
- The unambiguousness and significance of the questions
- The selection of the sample (culture, urban population, rural population)
For important articles that address the differences and diverging outcomes of erectile dysfunction prevalence studies, you should consult specific literature. In the following paragraphs we present you some selected studies.
Massachusetts Male Aging Study (MMAS)
One of the first studies on erectile dysfunction is the MMAS of the New England Research Institute. The study was conducted between 1987 and 1989 and involved men aged between 40 and 70. The presence of ED of varied severity was estimated to be at 52% in sum, with triple prevalence of erectile difficulty in subjects closer to the upper end of the age spectrum.
The aim of the study was to provide a comprehensive picture of physiological and psychosocial factors that influence men’s erectile function. For this, a random group of men from the Boston area were selected. The age of the men was between 40 and 70 years. The survey period was between 1987 and 1989. In a first step, the subjects collected physiological, medical, psychological and social variables from interviewers.
- blood samples
- physiological measurands
- sociodemographic information
- psychological variables
- health information
- lifestyle information (such as smoking).
In the second step, the subjects were questioned by questionnaire about information on sexual activity including erectile dysfunction. As a result, 52% of men reported at least occasional erectile dysfunction. The frequency of a full erectile dysfunction was between five and 15%, depending on the age. The number of men with erectile dysfunction increased with age.
The study then examines further influences on erectile dysfunction and corrects for the age effect. The authors found links between erectile dysfunction and cardiovascular disease, high blood pressure, diabetes, medication, and stress and depression. Men who smoke and have a disease are also more likely to be affected by erectile dysfunction. Men with high sex hormone levels or a more dominant personality were less likely to be affected by erectile dysfunction.
Men’s Attitudes to Life Events and Sexuality (MALES)
This is one of the most inclusive studies among Caucasian men of varied age; the study involved male population from North and South America, as well as Europe. The number of participants was 27,839 men aged between 25 and 75 in the Phase I of the study, with additional contingent of 2912 in Phase II.
The study showed that 16% respondents in both phases were affected by ED, but the results varied from one country to another. The highest incidence of ED was reported in the US (22%) and the lowest in Spain (10%).
In a second step, men with erectile dysfunction were interviewed in more detail. These men are made up of some of the previously interviewed men and men with erectile dysfunction from other interviews.
In total, 16% of men said they had erectile dysfunction. The frequency varies considerably between countries – in Spain it was ‘only’ 10%, in the US it was 22%. The incidence of erectile dysfunction increases significantly with age. Furthermore, erectile dysfunction is more likely to be associated with conditions such as cardiovascular problems, diabetes, hypertension or depression.
Other findings include that only 58% of men with erectile dysfunction seek medical treatment. Of these men, only a part is treated with PDE5 inhibitors such as Viagra – extrapolated to all men with erectile dysfunction 16% take a sexual enhancer.
A specially developed and previously tested questionnaire (Cologne ERECT for Erectile Dysfunction, short KEED) was sent in 1998 to a representative sample of 8000 men between 30 and 80 years from the district of Cologne. 4883 completed questionnaires were returned, of which 4489 could be used.
In addition to determining the prevalence of erectile dysfunction, the study should also identify the major comorbidities. Here we limit ourselves to the results regarding the prevalence. The main finding is that 19.2% of all men between the ages of 30 and 80 experienced erectile dysfunction. But only about one third of these men (6.9% of all men) suffer from erectile dysfunction and therefore need treatment. The rest have no problem with their potency disorder. With age, the frequency of erectile dysfunction increases significantly.
The decision on the presence of an erectile dysfunction is based on clear questions. Only question 16 (‘Are you able to reach an orgasm?’) Is not clearly aimed at erectile dysfunction. The answer to this question is probably more information about a possibly existing orgasm disorder (anorgasmia). Overall, the Cologne study is a painstaking work, based on a large number of men surveyed compared to other studies.