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and assessing treatment satisfaction. Some examples of such instruments are the International
Index of Erectile Function (IIEF), 15 the modified 5-item version of IIEF (IIEF–5), 16 and the
Erectile Dysfunction Index of Treatment Satisfaction (EDITS). 17 The IIEF is a self-administered
15-item questionnaire consisting of five distinct domains: erectile function (total score range 1–
30), orgasmic function (total score range 0–10), sexual desire (total score range 2–10),
intercourse satisfaction (total score range 0–15), and overall satisfaction (total score range 2–
10). 18
Recommendations based on biochemical investigation may consist of hormonal screening to
detect hypogonadism or other underlying common diseases such as hyperprolactinemia, diabetes
and dyslipidemia. 19,20 Other methods that may be used are urine analysis, blood count, lipid
levels, or prostate-specific antigen (PSA) concentration. 1 There are also specialized evaluation
techniques such as duplex ultrasonography, penile tumescence studies, RigiScan, test injections,
audio-visual stimulation and penile brachial index measurement. 21
Epidemiology of Erectile Dysfunction
ED is a common disorder of male sexual function that affects all age groups and has a
profound impact on quality of life. 2 Given the increasing trends in life expectancy across the
Western world (i.e., the aging of the general population) and the high prevalence of diabetes and
cardiovascular disease, the impact on lifestyle and quality of life imposed by ED in men is
projected to be substantial. 1 It was estimated that, in 1995, over 152 million men worldwide
experienced ED. For 2025, the prevalence of ED is predicted to be approximately 322 million
worldwide. 22 The severity, prevalence and incidence of ED increase with age. 2,22,23 The
Massachusetts Male Aging Study 2 surveyed 1,709 men aged 40–70 years between 1987 and
1989, using a self-administered questionnaire that asked participants to rate themselves as not
having ED, or having minimal ED, moderate ED, or complete ED. There was a total prevalence
of erectile dysfunction of 52 percent when participants with minimal (17.2 percent), moderate
(25.2 percent) and complete (9.6 percent) dysfunction were combined. 2 Both the prevalence and
severity of erectile dysfunction increased proportionally with age. When adjusted for age,
patients with lower level of education, heart disease, hypertension, and diabetes had a higher
probability of ED. 2,23 In the same study, a sample of 847 men without ED at baseline (1987–
1989) was followed prospectively until 1995–1997. 23 The crude incidence rate of ED in this
population was estimated to be about 26 cases per 1,000 man-years (95% CI: 22.5–29.9). The
annual age-specific incidence rate of ED increased with each decade of age. For example, the
incidence rates (and 95% CIs) for men in two age groups of 50–59 and 60–69 years were 29.8
cases per 1,000 man-years (95% CI: 24.0–37.0) and 46.4 cases per 1,000 man-years (95% CI:
36.9–58.4), respectively. 23 In a Canadian cross-sectional survey of primary care facilities, about
50 percent of 3,921 men aged 40–88 years had ED (IIEF “EF” domain score <21). 24 The
presence of cardiovascular diseases or diabetes was associated with an increased risk of having
ED after adjustment for age and other confounders. 24
Classification of Erectile Dysfunction and Related Conditions
Today, ED is considered a disorder with multiple causes. The current evidence suggests that
about 80 percent of ED cases are of organic origin. 1 Organic causes of ED may be vascular (e.g.
cardiovascular disease, hypertension, lipid disorders, endothelial dysfunction), neurological (e.g.
spinal cord injury, Parkinson’s disease, multiple sclerosis), iatrogenic (e.g. pelvic surgery,