Prevalence of Male Sexual Dysfunctions
The Massachusetts Male Aging Study (MMAS) is perhaps recognized as the first population-based study offering a determination of the prevalence rate of ED . This study, which comprised a sample of 1,800 men surveyed in a Boston, MA area from 1987–1989, reported a prevalence rate of 52% for any level of ED (including minimal, moderate, and complete presentations) and that of 35% for moderate or complete ED. The study also documented the relationship of age and ED, determining that the prevalence rates of complete ED (no ability to achieve an erection) increased from 5% to 15% for men between the ages of 40 and 70 years. The study comprised mainly of Caucasian men within this age range only, and thus, it is not useful to draw conclusions about national variations in race and ethnicity or the prevalence of ED in men over the age of 70 years.
The National Health and Social Life Survey, a cross-sectional interview survey conducted in 1992, which included 1,410 men aged 18–59 years throughout the United States, found that approximately 10% of the respondents had “trouble maintaining or achieving an erection,” and the prevalence of any form of sexual dysfunction in men was 31% . The study also evaluated sexual dysfunctions other than ED including low desire (approximate overall rate of 15%), and inability to achieve orgasm (approximate overall rate of 8%). An age-associated decline in sexual problems was also confirmed. Compared to the referent group of men aged 18–29, the oldest cohort of men (ages 50–59 years) were more than 3.5 times as likely to experience ED (95% confidence interval [CI], 1.8–7.0), nearly three times as likely to experience low sexual desire (95% CI, 1.6–5.4), and two times as likely to experience inability to achieve orgasm (95% CI, 0.79–3.83). “Climaxing or ejaculating too rapidly” was the most commonly indicated sexual dysfunction in this study, affecting approximately 30% of respondents with similar rates across age groups.
The Health Professions Follow-up Study, which involved a sample of more than 31,000 men aged 53–90 years surveyed in 1992, found that ED based on the conservative criteria of poor to very poor function was 33%, ranging from about 25% among those younger than 59 years to 61% in individuals older than 70 years . The study also demonstrated that many aspects of sexual function decreased sharply by decade after 50 years of age. For age groups 53–59 years, 60–69 years, 70–79 years, and older than 80 years, respectively, “very good” overall sexual function was 44%, 25%, 8%, and 2%; “very good” sexual desire was 34%, 24%, 12%, and 6%; and “very good” ability to reach orgasm was 51%, 33%, 13%, and 4%. The study also reported the extent to which sexual function is a “big” problem, with percentages for the respective age groups of 3%, 7%, 13%, and 19%.
A report based on the release of the 2001–2002 National Health and Nutrition Examination Survey (NHANES), a population-based survey comprising of 2,126 men from 20 to greater than 75 years of age representing broad racial and ethnic groups in the United States, established an 18.4% ED prevalence rate, based on self-reporting of being “sometimes able or never able to keep an erection adequate for sexual intercourse”. An age relationship with ED was shown, with a prevalence of ED, as previously defined, found to increase steadily from 6.5% in men aged 20–39 years to 77.5% in those 75 years and older. The percentage of the participants with the most severe ED, measured by reporting being never able to maintain an erection, increased from 2% to 47% between the indicated age categories. Hispanic men reported ED at approximately twice the rate as Caucasians (12.5% vs. 4.9%), after controlling for other ED-related factors such as diabetes, obesity, and hypertension . Modifiable risk factors independently associated with ED included diabetes mellitus (odds ratio [OR], 2.69), obesity (OR, 1.60), current smoking (OR, 1.74), and hypertension (OR, 1.56).
A separate analysis of the 2001–2002 NHANES database, corroborated the aforementioned analysis, also establishing 18.4% ED prevalence rate for the United States male population . Further analysis of the cardiovascular risk factors established age-adjusted ED prevalence rates of 38.6% (95% CI, 28.7–49.5) among men with diabetes mellitus, 15.1% (95% CI, 10.6–20.9) and 27.7% (95% CI, 21.4–35.0) among men with treated and untreated hypertension, respectively, 24.7% (95% CI, 18.1–32.7) among men with a history of cardiovascular disease, 17.0% (95% CI, 14.3–20.1) among men with hypercholesterolemia, 19.6% (95% CI, 13.9–26.8) among men with history of benign prostate enlargement, and 23.3% (95% CI, 20.0–27.0) and 12.6% (95% CI, 9.8–16.2) among men performing no physical activity and vigorous physical activity, respectively.
Another nationally representative survey, the Male Attitudes Regarding Sexual Health Survey, conducted in 2001–2002, included men older than 40 years of age and oversampled minority individuals. In this study, the estimated prevalence of moderate or severe ED, defined as a response of “sometimes” or “never” to the question, “How would you describe your ability to get and keep an erection adequate for satisfactory intercourse?” was 22.0% (95% CI 19.4–24.6) overall . ED prevalence rates were 21.9% (95% CI, 18.8–24.9) among 901 non-Hispanic white men, 24.4% (95% CI, 18.4–30.5) among 596 non-Hispanic black men, and 19.9% (95% CI, 13.9–25.9) among 676 Hispanic men. The study found that rates increased with age, diabetes, hypertension, and moderate or severe lower urinary tract symptoms.
Additional studies have recently been conducted affirming the global extent of male sexual disorders. The Global Survey of Sexual Attitudes and Behavior represented a collection of data of more than 27,000 men and women aged 40–80 years conducted between 2001 and 2002 in 29 countries . “Early ejaculation” was the most commonly reported dysfunction in men occurring at a 14% (95% CI, 14–15) rate, having the greatest frequency in Asia, Central/South America, and non-European Western countries. “Erectile difficulties” were the second most frequent dysfunction in men, reported as an overall rate of 10% (95% CI, 9–10), with the greatest rates in Asian countries. An age-dependent decline in all male sexual functions including lack of sexual interest and inability to reach orgasm was confirmed in this study.
The Men's Attitudes to Life Events and Sexuality Study, a survey conducted in 2001 of more than 27,500 randomly recruited men aged 20–75 years in eight countries including the United States, the United Kingdom, Germany, France, Italy, Spain, Mexico, and Brazil, produced an overall ED prevalence rate of 16% . Similar to prior discussed studies, the prevalence of ED increased with increasing age and the presence of comorbid conditions such as cardiovascular disease, hypertension, dyslipidemia, and depression.
Overall, notwithstanding variations in definitions, methodology and study populations, these reports substantiate the global presence and extent of sexual dysfunctions in men. ED has been the most thoroughly studied dysfunction, with an estimated overall prevalence rate that ranges between 10% and 20% worldwide. Racial/ethnic and geographic analyses affirm the significance that one in five men experience ED. However, other sexual dysfunctions are also common. The studies have also affirmed the correlates of age and comorbid health conditions with various sexual dysfunctions.
Incidence of Male Sexual Dysfunctions
Few epidemiologic studies exist which address the incidence of male sexual dysfunctions. Such studies are valuable to assess the risk and plan treatment and prevention strategies. Longitudinal results of the MMAS with follow-up through 1997 have offered population-based incidence data for ED . The crude ED incidence rate was 25.9 cases/1,000 man-years (95% CI, 22.5–29.9) among men aged 40–69 years. The annual incidence rate increased with each decade of life: 12.4 cases/1,000 for men aged 40–49 years (95% CI, 9.0–16.9); 29.8 cases/1,000 for men aged 50–59 years (95% CI, 24.0–37.0); and 46.4 cases/1,000 for men aged 60–69 years (95% CI, 36.9–58.4). The age-adjusted risk was found to be higher for men with lower education, diabetes, heart disease, and hypertension.
The MMAS database was also used to examine coronary risk factors that may predict the development of ED in a “healthy” subsample of men free of ED or vascular disease at baseline . Among several risk variables, cigarette smoking, cigar smoking, passive exposure to cigarette smoke, and overweight status were significant predictors of incident ED.
A side analysis of the recently conducted Prostate Cancer Prevention Trial has also produced incidence data for ED . The trial, which began in 1994, consisting of more than 18,800 men aged 55 years or older, was designed to assess whether finasteride would reduce the prevalence of prostate cancer over a period of 7 years. Among 9,457 men randomized to the placebo group, 2,420 men (57%) of 4,247 men without ED at study entry reported incident ED after 5 years, and this rate increased to 65% at 7 years. Interestingly, the study showed that incident or prevalent ED generated a hazard ratio of 1.45 (95% CI, 1.25–1.69) for subsequent cardiovascular events, which is estimated to be in the range of risk associated with current smoking or a family history of myocardial infarction.