The use of the simplified International Index of Erectile Function (IIEF-5) as a diagnostic tool to study the prevalence of erectile dysfunction

Abstract

The purpose of this research was to determine the prevalence of erectile dysfunction (ED) in a non-selected population using the abridged 5-item version of the International Index of Erectile Function (IIEF-5) as a diagnostic tool. In a non-institutionalized population and during a free screening program for prostate cancer (Prostate Cancer Awareness Week of Santa Casa Hospital, Porto Alegre, Brazil), from 26 to 30 July 1998, all men who were attending were invited to complete a sexual activity questionnaire (the abridged 5-item version of the International Index of Erectile Function-IIEF-5) as a diagnostic tool for ED. The possible scores for the IIEF-5 range from 5 to 25, and ED was classified into five categories based on the scores: severe (5–7), moderate (8–11), mild to moderate (12–16), mild (17–21), and no ED (22–25). Of the 1071 men who participated in the program, 965 (90.1%) were included in this study. Of the responding men 850 were Caucasian (88%) and 115 were black (12%). The mean age of the men was 60.7 y, ranging from 40 to 90 y old. In this sample the prevalence of all degrees of ED was estimated as 53.9%. In this group of men, the degree of ED was mild in 21.5%, mild to moderate in 14.1%, moderate in 6.3%, and severe in 11.9%. According to age the rates of ED were: 40–49 (36.4%); 50–59 (42.5%); 60–69 (58.1%); 70–79 (79.4%), and over 80 y (100%) showed ED (P<0.05). The Pearson coefficients between the variables age and IIEF-5 showed a statistically significant inverse (negative) relation (r=−0.3449; P<0.05). ED is highly prevalent in men over 40 and this condition showed a clear relationship to aging, as demonstrated in other studies published. The simplified IIEF-5, as a diagnostic tool, showed to be an easy method, which can be used to evaluate this condition in studies with a great number of men.

Introduction

Erectile dysfunction (ED) is defined as the persistent inability to achieve and maintain an erection sufficient to permit satisfactory sexual intercourse.1,2,3

Incidence and prevalence of ED are considerable and awareness is growing that the condition is treatable.1,4 Despite the increasing demand for clinical services and the potential impact of ED and other sexual disorders, on interpersonal relationships and quality of life, epidemiological data are relatively scarce.5,6,7

The prevalence of ED depends on the population studied and the definition and methods used. Since ED often accompanies aging and is associated with chronic illness, such as diabetes mellitus, heart disease, hypertension, and a variety of neurological diseases, very few studies have been carried out to establish the incidence and prevalence of this condition in a healthy population.8 In a community-based survey of men between the ages of 40 and 70 y, 52% of the respondents reported some degree of erectile difficulty. Based on these data it is estimated that ED affects 20–30 million men in the USA.2

Although laboratory-based diagnostic procedures are available, it has been proposed that sexual function is best assessed in a naturalistic setting with patient self-report techniques, particularly in multicenter, multinational and epidemiological clinical trials.9

The objective of the present study is to use the abridged 5-item version of the International Index of Erectile Function (IIEF-5)10 as a diagnostic tool for establishing the prevalence of ED in a normal healthy population.

Materials and methods

The ethics committee at our hospital approved this study. Patients were previously informed of the research details and they agreed to participate in the study. Informed consent was obtained at the interview.

All the men attending a screening program for prostate cancer (Prostate Cancer Awareness Week of Santa Casa Hospital-Porto Alegre, Brazil) from 26 to 30 July 1998 were asked to answer the 5-item version of the IIEF10 to determine the prevalence of ED. This was a non-institutionalized population and included 1071 men.

As previously described this questionnaire consists of only five questions and each IIEF-5 item is scored on a five-point ordinal scale where lower values represent poorer sexual function.10 Thus, a response of 0 for a question was considered the least functional, whereas a response of 5 was considered the most functional. The possible scores for the IIEF-5 range from 1 to 25 (one question has scores of 1–5), and a score above 21 was considered as normal erectile function and at or below this cutoff, ED. According to this scale, ED is classified into four categories based on IIEF-5 scores: severe (1–7), moderate (8–11), mild to moderate (12–16), mild (17–21), and no ED (22–25). Trained physicians from the urology staff interviewed each of the men in an individual room with a total guarantee of confidentiality.

The screening was advertised in print and electronic mass media and participants were self-selected, according to order of arrival at the evaluation site, after responding to media publicity. The media was only directed to prostate evaluation. All men who were patients of the hospital Institutional Division of Urology or Andrology, as well as, those who were using intracavernous pharmacology therapy, oral drugs for ED, penile prothesis and patients with major psychiatric disorders or penile anatomical disorders or who reported no sexual activity during the last 6 months were excluded from the study analysis. Men who did not speak Portuguese were excluded from the study.

The Chi-square test was used for statistical analysis as well as the Pearson correlation which was calculated for the variables age and IIEF-5 in the study. A value of P<0.05 was considered statistically significant.

Results

Of the 1071 individuals seen, 965 (90.1%) were included in the present study. One hundred and six men were excluded (9.9%) because of failure to complete all of the criteria in the protocol. The frequency distribution of the men according to the different age groups is shown in Figure 1. Of the responding men 850 were Caucasian (88%) and 115 were black (12%).The mean age was 60.7 y, ranging from 45 to 90.

Figure 1
figure1

Distribution of the subjects according to the age groups included in the study of erectile function.

In this sample the prevalence of all degrees of ED was estimated at 53.9%. In this group of men, the degree of ED was mild in 21.5%, mild to moderate in 14.1%, moderate in 6.3%, and severe in 11.9% (Table 1). According to age the ED rates were: 40–49 (36.4%); 50–59 (42.5%); 60–69 (58.1%); 70–79 (79.4%), and over 80 y (100%) showed ED, which was statistically different among all the age groups (P<0.05), except between 40–49 and 50–59 y (P>0.05; Table 2).

Table 1 Prevalence of erectile dysfunction in the population studied
Table 2 Prevalence of erectile dysfunction (ED), in the different age groups

The relationship between different degrees of ED probabilities and age of the subjects studied is illustrated in Figure 2. We can observe that the normal erectile function declines with advancing age and ED, mainly severe, was progressively more likely in the aging male. Subjects aged 70 have more than double the ED when compared with men aged 40 y. An estimated 63.6% of the men have no ED at the age of 40, with a decrease to 20.6% at 70 y and 0% at age 80. Mild and intermediate degrees of ED have a similar prevalence in the different age groups.

Figure 2
figure2

Association of subject age with probability of erectile dysfunction imputed by discrimination analysis in 965 respondents to the abridged 5-item version of the International Index of Erectile Function.

The Pearson coefficient between age and incidence of ED showed a significant inverse correlation (r=−0.3449; P<0.05) (Figure 3).

Figure 3
figure3

Correlation between erectile function and age of the population studied.

Discussion

The present study was based on a cross-sectioned outline of non-institutionalized men with ages distributed between 40 and 90 y, from a center designated for the treatment of urological diseases. These men were invited to participate in a free screening program for prostate cancer. Completing a sexual activity questionnaire was only mentioned during the interview at the office.

The data in this study do not represent a randomly selected population from within a community but are from men seeking medical attention in a free screening program. It is possible, therefore, that these data might not represent the country or even regional status. People seeking medical attention in a screening program may be more concerned with their own health that the general population but, on the other hand, patients with co-morbidity and low quality of life might have no interest in participating in this type of program.

The erectile function in this study was based on subject responses to a privately administered questionnaire by a physician. Recently, Lehmann et al.11 demonstrated that ED could not be defined by pharmacostimulated erection but relevant ED was honestly reported. As referred by Rosen et al.10 the IIEF-5 is intended to complement, not supplant, clinical judgment and useful diagnostic assessments. It may be particularly useful as an initial screening instrument in the general practice setting, mainly when we consider the progressive advent of recently available oral therapeutics for the treatment of ED. In epidemiological studies, when many people are assessed, a simple, practical and valid questionnaire is essential.

The IIEF is a multidimensional validated questionnaire with 15 questions in the five domains of sexual function (erectile and orgasmic functions, sexual desire, satisfaction with intercourse and overall sexual satisfaction) approved by the National Institutes of Health (NIH).1 Its purpose to unify the language used in studies with the intention of defining the prevalence of ED in different populations and countries.9 More recently, to simplify the IIEF an abridged 5-item version of this (IIEF-5) was developed as a diagnostic tool for ED.10 It consists of five selected items to clearly discriminate between subjects with and without ED, as well as address the NIH1 definition of this condition. This simplified version, proved to be a valid specific and sensitive scale for use in the clinical setting.10,12

ED has been described as an important public health problem by the NIH Consensus Panel,1 which identified an urgent need for population-based data concerning the prevalence, determinants, and consequences of this disorder.6

As previously observed, the prevalence of ED depends on the population studied and the definition of this condition and methods used.5,13,14,15 These aspects can explain the varied data of the 52% prevalence from a study in the USA,2 32% from a study in the UK, 26% in Japan and 19% from a study in Denmark.10

Studies performed in a select population with pathological conditions such as diabetes mellitus, heart disease or in institutions which provide attention for patients with specific andrologic diseases do not represent the true prevalence of ED in the general population. Another aspect is the fact that many studies using different questionnaires and definitions of ED have significant influence on the data obtained.

Potency, defined as satisfactory functional capacity for erection, may coexist with some degree of ED in the sense of submaximal rigidity or submaximal capability to sustain the erection.16,17,18 Therefore, erectile function is best defined by the individual as assessment of his own situation in simple terms of minimal, moderate or complete as presented to a physician for treatment.9,17

Although ED can be primarily psychogenic in origin, most patients have an organic disorder (vascular, neurologic, endocrine disorders), commonly with some psychogenic overlay.19,20,21 Some men assume that erectile failure is a natural part of the aging process and tolerate it; for others it is a devastating condition. Withdrawal from sexual intimacy because of fear of failure can damage relationships and have a profound effect on the overall relationship of the couple. The decrease of sexual activity has been frequently associated with the aging process.22,23,24 Normally, several causes had associated ED with aging, which include, vascular insufficiency, hormonal disturbances, neuropathies, diabetes mellitus, psychological factors and side effects of drugs usually used more by this population.25

Sexual function progressively declines in healthy aging men. For example, the latent period between sexual stimulation and erection increases, erections are less turgid, ejaculation is less forceful, the ejaculatory volume decreases, and the refractory period between erections lengthens.26 There is also a decrease in penile sensitivity to tactile stimulation, a decrease in the serum testosterone concentrations, and an increase in cavernous muscle tone.26

In this cross-section study, with men who were invited to participate in a screening program for prostate cancer, and who were not informed previously that their sex life would be assessed, the prevalence of all degrees of ED was 54.5%, similar to the results obtained by Feldman et al.2 in the ‘Massachusetts Male Aging Study’ (MMAS), which was 52%, although several considerations have to be made regarding methodological aspects.

As demonstrated in Table 2, the mean values of the IIEF-5 scores, in all age groups, decreased progressively with age.

We can observe that the rates of ED were 37.5% in the group aged 40–49, 43.3% in the 50–59 group, 60% in the 60–69 group, 81% in the group aged 70–79 y and 100% of the men had been classified with ED (all degrees) when ages over 80 y were considered. The absence of a statistical difference between the groups aged 40–49 and 50–59 can be attributed to the small number of subjects in the fourth decade of life evaluated in the present study. This aspect is explained by the fact that in the media campaign men over 50 y were invited to participate of the screening program.

Although, again data very similar to ours were observed by Feldman et al2 in the epidemiological study of MMAS, in which the rate of ED was 39% in the age group 40–49 y, 48% in those aged 50 y, 57% in those aged 60 and 67% in the 70-y group. Very few studies evaluated ED in men over 70. Some authors, such as Morley,3 referred to a 75% rate of ED in men 80 or over.

In the present study an interesting aspect is the high prevalence of ED in men over 70 y old. This aspect is very important because very few studies in the literature have reported the erectile condition in this select aged population.

Another significantly relevant aspect observed in the present study showed a high rate of severe degree and decrease in frequency of mild degree of ED with aging. This aspect can be best explained when we observe, for instance, that in the age group 40–49, nearly 90% have a mild degree of ED, but 70% have a severe degree of ED when we select the population over 80 y old. On the other hand, in these same groups 62.5% of the men mentioned normal erectile function in the fourth decade, although this rate fell to 19% and 0% in the ages groups 70–79 y and over 80 y, respectively.

The characteristic relationship between the probability of complete ED and the age of the individuals could also be observed in the MMAS,2 so between 40 and 70 y it increases 3-fold, from 5.1 to 15%, and the moderate degree of ED increased 2-fold, 17 to 34%, although, the mild degree of ED was similar, 17%, presented the two extremes. Around 60% of men have normal erectile function at 40 y but only 33% presented the same condition when men of aged 70 were considered.

In our experience, the simplified 5-item IIEF-5 used in this study was shown to be a simple and easy method for the evaluation of ED mainly when we consider epidemiological studies with a great number of individuals. This aspect is reinforced when we observe the low number of men excluded (9%) from the study, as well as, the characteristics of the results obtained. Another relevant aspect is the fact that the erectile condition or the severity of ED could be established when we used the questionnaire and probably easier than other methods. The evaluation of the erectile function with this method and the investigation of the association with risk factors for ED in others studies can establish health strategies and medical orientations to change the factors associated with this clinical condition and which will result in significant improvement for the difficult problems related to the aging process.

Conclusions

In conclusion, we and other authors observed that ED is more common with advancing age, data on prevalence being similar to those found in other countries.

From the data obtained in this population we can observe that ED is a condition highly prevalent in men over the age of 40, and that it is clearly related to advancing age in the different stratifications considered. Furthermore, age is thought to be the factor which has the strongest influence on erectile function and, therefore, can be considered to be an important risk factor for ED. Finally, the IIEF-5 was shown to be a useful instrument to evaluate the prevalence of ED and its degree in this unselected population and we agree that this method can be used in the future to establish the prevalence of this condition in epidemiological features with more uniform language.

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Rhoden, E., Telöken, C., Sogari, P. et al. The use of the simplified International Index of Erectile Function (IIEF-5) as a diagnostic tool to study the prevalence of erectile dysfunction. Int J Impot Res 14, 245–250 (2002). https://doi.org/10.1038/sj.ijir.3900859

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Keywords

  • erectile dysfunction
  • aging
  • erectile function
  • diagnostic tests
  • IIEF
  • epidemiology of erectile dysfunction

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