«Chapter 2 / Epidemiology of ED 47 2 Epidemiology of Erectile Dysfunction Ridwan Shabsigh, MD SUMMARY Erectile dysfunction (ED) is a highly prevalent ...»
Chapter 2 / Epidemiology of ED 47
2 Epidemiology of Erectile Dysfunction
Ridwan Shabsigh, MD
Erectile dysfunction (ED) is a highly prevalent condition among men all over the
world. It has a significant negative impact on the quality of life of the patients and their
partners. Its prevalence and incidence are associated with aging as well as important
comorbidities, such as cardiovascular disease, diabetes, metabolic syndrome, hyperlipidemia, depression, pelvic surgery, side effects of medications, neurological disorders, trauma, symptoms of benign prostate hyperplasia, and psychological and interpersonal problems. Furthermore, lifestyle choices of major public health impact are also associated with ED. These include preventable causes of disease such as obesity, smoking, alcohol abuse, and sedentary lifestyle. Recent studies have revealed that ED is not only a correlate of cardiovascular disease, diabetes, and metabolic syndrome; it is rather an early warning symptom. Studies on treatment-seeking behavior revealed significant barriers to seeking treatment for this condition and its important correlates.
Key Words: Erectile dysfunction; metabolic syndrome; risk factors for endothelial dysfunction; Massachusetts Male Aging Study; global sexual dysfunction.
PREVALENCE AND INCIDENCE OF ERECTILE DYSFUNCTIONED is defined by a National Institutes of Health consensus panel as the inability to achieve or maintain an erection sufficient for satisfactory sexual performance (1). Worldwide estimates of ED prevalence range from 2% in men younger than 40 yr to 86% in men 80 yr or older (2). Prins et al. (2) systematically reviewed 23 studies (including 15 from Europe, 5 from the United States, 2 from Asia, and 1 from Australia) and reported
From: Current Clinical Urology:
Male Sexual Function: A Guide to Clinical Management, Second Edition Edited by: J. J. Mulcahy © Humana Press Inc., Totowa, NJ 48 Shabsigh the prevalence of ED in population-based studies. They reported the drawbacks of some studies—namely, prevalence rates without classifying patients with ED into different age groups or without referring to the severity of ED and its nomenclature: mild/partial/ minimal, moderate/intermediate, complete/severe. Prevalence rates of ED among specific age groups were not reported in every study. This makes it difficult to draw solid conclusions regarding the prevalence of different degrees of severity of ED among different age groups. ED prevalence and severity increase with age. ED prevalence has been reported as 7% among men aged 18 to 29 yr, 2 to 9% among men aged 30 to 39 yr, 9 to 11% among men aged 40 to 49 yr, 16 to 18% among men aged 50 to 59 yr, 34% among men aged 60 to 69 yr, and 53% among men aged 70 to 80 yr (2).
The large variation in reported prevalence rates reflects differences in methodology, definitions of ED, regional and cultural perceptions of ED, age, and extent of concomitant medical conditions (2,3). Risk factors for ED include aging, comorbid disease, certain medications, obesity, and lifestyle behaviors (e.g., alcohol and tobacco use; ref. 4).
The prevalence of ED is not the same among different countries or continents nor among different ethnic groups. The prevalence rates for mild and severe ED has been reported as 35% in the United States, 26% in Finland, 21% in Italy, 12% in France, and 11% in Spain (5–9). In Malaysia, Low et al. (8) reported a difference in the concept of ED and its prevention and treatment among males from three different ethnic groups living in the country (Malay, Chinese, and Indian) without reporting the percentages of each group.
Among men consulting for ED in Israel, a multi-ethnic country, 13% were born in Israel, 33% were immigrants from North African (Morocco, Libya, Yemen) or other Middle East countries (Iraq, Iran), and 54% came from North and South America and Europe (9). The Cologne study shows an important difference between an overall ED prevalence of 19.2% among 71.3 to 96% men involved in regular sexual activity and 31.5 to 44% of responders who were dissatisfied with their current sex life (5). The prevalence of ED may be different, depending on the system used to perform the evaluation. ED prevalence has been reported as 12 to 25% on the basis of self-evaluation compared to 19 to 31.6% according to International Index of Erectile Function criteria (7–9).
Although much data exist regarding the prevalence of ED, there is little information regarding the incidence of dropout from treatment programs or discontinuation of followup visits. Among 4489 responders in the Cologne study, 46.2% were willing to contribute financially toward the cost of a regular treatment for ED (5). On the other hand, 9 to 25% of sildenafil responders discontinued successful treatment because of medication cost (10,11).
The Massachusetts Male Aging Study (MMAS), the first large-scale, population-based study of ED, found that the prevalence of ED correlated highly with age (12). This study also found that ED correlated with heart disease, hypertension, diabetes, and low levels of high-density lipoprotein cholesterol, independent of age. Using a large claims database of 28 million heath plan members in the United States, Seftel et al. (13) found that hypertension, hyperlipidemia, diabetes, and depression were prevalent in men with ED, suggesting that ED shares common etiological risk factors with these comorbidities.
Esposito et al. (14) showed that lifestyle changes, such as weight loss and increased physical activity, were associated with improvement in sexual function in about one-third of men with ED.
Many of the diseases associated with ED appear to affect the vascular system (e.g., atherosclerosis, hypertension, lipid disorders, myocardial infarction, cerebrovascular accidents, peripheral vascular disease, and diabetes mellitus; refs. 4 and 12). The erectile Chapter 2 / Epidemiology of ED 49 response involves a complex interaction between neurological, vascular, and hormonal processes. Accordingly, disorders that impair processes common to those that underlie the erectile mechanism (e.g., neural transmission, blood flow, or smooth muscle response) may play a role in ED (4). Recently, considerable attention has been given to the correlation between lower urinary tract symptoms (LUTS) and ED (5,15,16). LUTS— frequently caused by benign prostatic hyperplasia—is an aggregate of related voiding symptoms, including urinary frequency, urgency, nocturia, and slow stream. Although the pathophysiological link between LUTS and ED is not understood, the findings from several studies suggest that LUTS is a risk factor for ED, independent of age and other comorbidities (5,10,17).
The Cross-National Survey on Male Health Issues was a population-based, international survey for men regarding their health issues. The study was unique because it primarily measured the prevalence of ED in men who used health care systems. The objectives of the survey were to investigate the prevalence of ED, to evaluate treatment-seeking behaviors among these men, to assess their attitudes toward the condition, and to identify the barriers and motivators of seeking treatment for ED. The treatment-seeking behaviors of men with ED have been reported (18). The results have confirmed other populationbased reports that only a minority of men with ED seek treatment. Common barriers to seeking treatment included the belief that the condition would resolve on its own (primarily younger men) and the perception that ED was a normal part of aging (primarily older men). The study also confirmed the association of ED with age, overall health, and comorbidities such as hypertension, hyperlipidemia, diabetes, depression, and LUTS.
Men who currently or formerly suffered from ED comprised 19% of the population in the Cross-National Survey on Male Health study, which is consistent with reports from other population-based surveys(2,3), yielding an overall worldwide prevalence rate of 19%. Age was the primary variable that correlated with ED in this study. Respondents in the oldest age group (70–75 yr) had a 14-fold higher relative risk of experiencing ED than respondents in the youngest age group (20–29 yr). Across the six countries, ED prevalence rates increased from 4 to 6% in men younger than age 40 yr to 39 to 73% in respondents age 70 to 75 yr. These findings are consistent with those from another population-based study (2).
Information on the screening questionnaire allowed the assessment of the correlation between ED and overall health. The results of the analysis showed a significant positive correlation between ED and increasingly poor health, with respondents who reported poor health experiencing a fivefold higher risk for ED than respondents who reported excellent health. The results of the screening analysis showed a significant association between ED and LUTS, which is consistent with findings from other studies. The followup questionnaire completed by men who reported ED included several items related to demographics, comorbidities, and medication use. The most frequently reported comorbidities in this sample population of men in the health care system were hypertension and hyperlipidemia. Diabetes was also cited as a frequent comorbidity by a large number of men. These findings are consistent with reports from other population-based surveys (12, 17,19–21). In the MMAS, total serum cholesterol did not correlate with prevalence of ED, but high-density lipoprotein cholesterol was inversely correlated with ED (12). The prevalence of comorbidities for ED in our survey increased with increasing severity of ED when severity was based on either the International Index of Erectile Function or self-report. With the exception of anxiety, depression, and spinal cord injury, the rates of comorbidities increased with age. In our survey of men with ED in six countries, approx 50 Shabsigh 10 to 20% were taking β-blockers. Only a small percentage (2–8%) of men with ED used nitrates for comorbid cardiac disorders, which is important because many men with ED receive phosphodiesterase-5 inhibitors as first-line therapy, and this class of agents is contraindicated with nitrate use. Similarly to all epidemiological studies, there were inherent biases in the survey methodology and data analyses. The analyses performed using the data were post hoc and exploratory. As expected, because of the sensitivity of the subject matter and the fact that respondents answered in private and could leave blanks, large amounts of data were missing from the survey.
Results from the Cologne Male Survey of 8000 men in Germany revealed that the prevalence of LUTS was approx 72% in men with ED vs 38% in men without ED (odds ratio:
2.11; ref. 17). Multivariate analyses showed that the association of LUTS with ED occurred independently of age and other comorbidities such as diabetes, hypertension, and history of pelvic operations. Similarly, the results of the Multinational Survey of the Aging Male, which was conducted on approx 14,000 men in the United States and six European countries (United Kingdom, France, Germany, the Netherlands, Italy, and Spain), found that ED was strongly associated with LUTS severity (p 0.001), independently of age- and vascular-related comorbidities (15).
A noteworthy observation in the Cross-National Survey on Male Health Issues was that the prevalence of comorbidities increased with the severity of ED. This finding, in addition to data showing that ED correlated with overall health, indicates that ED is a prognostic marker of overall health and important diseases. Presentation of diseases such as hypertension, hyperlipidemia, diabetes, depression, and urinary problems should alert the primary care physician, urologist, cardiologist, or endocrinologist to the possibility of ED. For example, practitioners who see men with urinary symptoms have an opportunity to inquire about the possibility of ED, thereby providing a means for overcoming barriers to discussion and treatment. Conversely, the presence of ED should alert practitioners to the likelihood of other common comorbidities. Men with comorbid conditions, such as vascular diseases and LUTS, should be screened for ED, and men with ED should be screened for comorbid conditions. The results from this and similar surveys will improve identification and disease management as well as treatment paradigms for ED.
AGING AND ERECTILE DYSFUNCTION“A man is as old as his arteries”—Sir William Osler Because the penis is a vascular organ, it is true that a man is as old as his penis. The classical work by Kinsey (22) revealed that aging is a key risk factor for the development of male ED. In his pioneering work, Kinsey showed that the prevalence of ED increased with age from 0.1% at 20 yr to 75% at 80 yr. A half century later, the MMAS (12) showed the same trend—namely, the prevalence of ED increased from 39% in men in their 40s to 67% for men in their 70s. Using the same questionnaire as the MMAS study, the Cross-National Epidemiological Study was conducted in four different countries with varying cultures: Brazil, Italy, Japan, and Malaysia (23). The results confirmed the findings of the MMAS with an age-dependent increase in the prevalence of ED in these different countries.
The world is getting older and older, especially in developed countries. Japan is the most aged and still aging country in the world. We see the future of the rest of the world by studying what happens in Japan. The ministry of the Health and Welfare of Japan has Chapter 2 / Epidemiology of ED 51 projected that the percentage of the population over 65 yr will represent as much as 20% by the year of 2010. The French, German, and Swedish populations will have a similar distribution based on age by the year 2020. The British and American populations are lagging and, therefore, will not reach 20% of the population over age 65 until the year