«Chapter 2 / Epidemiology of ED 47 2 Epidemiology of Erectile Dysfunction Ridwan Shabsigh, MD SUMMARY Erectile dysfunction (ED) is a highly prevalent ...»
2030. Because age has been shown to be a significant risk factor for all types of sexual dysfunction, we anticipate that with the growing population over age 65, there will be an enormous number of patients with either ED or sexual dysfunction (24).
Another key factor is treatment-seeking behavior. The marketing of sildenafil in Japan is a striking example of how aging affects treatment-seeking behavior. Despite the fact that Japan has a significant elderly population, the sales of sildenafil have been disappointing on a per capita basis. Only 800,000 (8%) of the estimated 10,000,000 patients received prescriptions for sildenafil (23). This is especially surprising because neither Caverject nor MUSE® are available in Japan. My colleagues and I (18) reported the treatment-seeking behavior in six different countries (the United States, France, Germany, Italy, Spain, and the United Kingdom). They showed that treatment-seeking rate has a peak during middle age, with the exception of in the United States. The most common reason for the older age group to not seek treatment is their impression that “ED is a natural part of aging.” Therefore, aging did not directly increase the cost of ED diagnosis and treatment. We have to estimate the cost by combining the age demographics and the treatment-seeking rate in each country or each culture. However, if we manage to eliminate this kind of stigma by educating the medical professionals and the public—especially among the older people— the cost will be much higher.
RISK FACTORS FOR ERECTILE DYSFUNCTIONAccording to the United Nations, by 2025, there will be more than 356 million men older than age 65 worldwide, an increase of 197 million from the current number. In 1995, the global proportion of men older than age 65 was 4.2%; this is expected to rise to 9.5% by
2025. Because of the correlation between ED and age, global aging will bring an increase in the number of men with ED in the future. ED is commonly associated with aging and age-related health problems, such as vascular, hormonal, neural, psychogenic factors, and side effects of therapeutic drugs. Current data on ED among the healthy population— particularly for physiological and psychosocial variables—is extremely lacking, despite the prevalence and implications of ED on quality of life (24).
ED is common in men with cardiovascular disease and is probably brought about by shared factors that impair the hemodynamic mechanisms (25,26). The majority of patients with ED have at least one significant cardiovascular risk factor (e.g., hypertension, diabetes mellitus, smoking, or hyperlipidemia). Therefore, vasculogenic ED may be the harbinger of a systemic vasculopathic state.
MMAS results showed the age-adjusted probability of the onset of moderate ED increased from 6.7 to 25% as high-density lipoprotein cholesterol decreased from 90 to 30 mg/dL in younger men (40–55 yr) and from 0 to 16% in older men (56–70 yr; refs.
18 and 24). In the study, heart disease and associated risk factors, hypertension, and lowserum high-density lipoprotein significantly correlated with ED (25,26). Oaks and Moyer reported that 8 to 10% of all untreated hypertensive patients were impotent the time that hypertension was diagnosed (26a). Furthermore, Wabrek and Burchell reported that in a group of 131 men with acute myocardial infarction between ages 31 and 86 yr, 64% were 52 Shabsigh impotent; additionally, in a study of patients who underwent coronary artery surgery, 57% were mostly impotent (26b). In a study of men in a hypertension center, ED was found to be highly prevalent and severe in men with hypertension (27). Furthermore, ED was found to be a prognostic marker of the complications of hypertension—namely, myocardial infarctions and cerebrovascular accidents (28).
Diabetes is another major illness associated with ED. In the MMAS sample, the agerelated probability of complete ED was three times greater in patients with diabetes than in those without diabetes. Other studies using diabetic populations have consistently found a high prevalence of diabetes-related ED, with estimates ranging from 35 to 50% and up to 75%. The prevalence of ED in patients with diabetes has been reported to increase from 15% in men aged 30 to 35 yr to 55% in men aged 60 yr. ED occurs at an earlier age in people with diabetes than in the general population and often follows, or leads to, the diagnosis of either insulin-dependent or non-insulin-dependent diabetes (24,25).
The exact link between ED and depression is not well defined, because its significance is twofold; depression can be both a cause and an effect of ED (29). Depression has numerous ED-correlated symptoms: changes in sleep patterns, decreased interest in and response to pleasurable activities, and anticipation of a negative outcome. However, depression brought on by episodes of ED may perpetuate erectile failure, cause deeper depression, and result in the avoidance of sexual opportunity, even with an effective treatment. In the MMAS study, patients with depression had a 1.82 higher chance of developing ED than patients who did not suffer from depression.
The link between cigarette smoking and ED is not clearly understood (30–32). The MMAS sample did not show a significant difference in cases of ED between current smokers and nonsmokers. However, the association of ED with certain risk factors was greatly amplified in current smokers. According to MMAS data analysis, the age-adjusted probability of complete ED in subjects treated for heart disease was 56% for current smokers compared to 21% for nonsmokers. Furthermore, the Vietnam Experience Study found that the prevalence of ED was 1.5-fold greater in current smokers copared to nonsmokers. A cross-sectional study conducted in Italy comparing nonsmokers and current smokers and exsmokers in 2010 men older than age 18 yr presented an odds ratio of ED of 1.7 and 1.6, respectively. The study also showed that the risk of developing ED is influenced by smoking and that the duration of the habit increases this risk.
Other important factors include heavy alcohol consumption, obesity, and physical activity. Chronic, heavy alcohol consumption may have an irreversible effect on erectile function because of neurological damage; specifically, changes in drinking habits may not influence erectile function. Chronic drug abuse, especially combined with alcohol consumption, can lead to erectile disorders, specifically because of behavioral changes (32). The link between ED and the use of certain medications is underestimated.
A close link exists between ED and pelvic surgery, with rates ranging up to 80%. In this case, radical prostatectomy, cystectomy, and radical pelvic surgery are considered. Transurethral resection of the prostate plays an unclear role (33).
The rise in the prevalence of worldwide ED, coupled with the new high-profile medical treatments, is raising policy issues (24). National health systems that are already underfunded are facing unexpected requests for resources and challenges to current government funding priorities. The wide range of treatment options available since the arrival of new oral drugs effective for the treatment of ED has, above all, re-opened the debate over rationing and funding priorities.
Chapter 2 / Epidemiology of ED 53
IMPACT OF ERECTILE DYSFUNCTIONED is highly prevalent, the incidence is strongly age-related, and it is progressive and undertreated (34). The word population is rapidly aging. In 2000, 13% of the world’s population was older than 65 yr, and it is estimated that by 2020, this population will increase to 20%. The projections made in 1998—namely, that a fourfold increase in the ED industry would occur by 2002, from about $0.9 to $5 billion—have been proven (35, 36). The impact of a condition with such escalating proportions seems obvious. The economical impact of a medical condition or disease is not limited by the cost of diagnosis and treatment, but it includes the impact on the patient and society in various ways, such as loss of time at work, decreased productivity for the patient, and the effect on the partner, the family, and co-workers. The impact is further confounded by the correlates of ED, which have a high economical impact, such as atherosclerosis, myocardial infarction, hypertension, diabetes mellitus, depression, and conditions of the prostate, such as benign prostatic hyperplasia and cancer of the prostate.
Economical An attempt was made to estimate the economical impact of ED in the United Kingdom (24,36). In this study (conducted from 1997 to 1998) on the cost of ED in the National Health Service (NHS), it was estimated that £53 million was spent to manage 113,600 patients with ED (36). The main cost driver was outpatient visits, which accounted for 65% of the cost. Drugs accounted for 25% and genito-urinary consultations, and prostheses accounted for only 4% of the cost. It was estimated that the NHS managed 35% of the population with ED. Assuming that this was representative, the total population of individuals in the United Kingdom was estimated to be approximately 325,600. It has been further estimated that these men incur £7.0 million in cost directly attributable to ED (19.63 d/yr to lost work), thus costing the society another £2.2 million in lost gross domestic product. It was concluded that ED imposes a relatively small economical burden on the UK Society (£53 million), of which 83% is borne by the NHS, 13% is borne by patients, and 4% is borne as indirect costs to society resulting from lost productivity. The authors stated that the future burden would depend largely on patient’s eligibility to receive treatment under the NHS.
In an attempt to curb expenditure, the NHS imposed prescribing restrictions for ED under Schedule 11. Wilson et al. (37) assessed the effect of these restrictions. During the period of the study (1997–2000), a 30% increase in the number of patients (79,800 to 257,984) and a 40% increase in cost (£29.4 million to £73.8 million) were observed. The actual expenditure per patient decreased by 22% from £368 to £286 and the main expenditures were ascribed to specialist consultations (30%) and drug prescriptions (25%).
The increased cost mainly resulted from a threefold increase in the number of patients presenting to general practitioners, who then referred patients to specialists because of Schedule 11 restrictions. This led to an increased use of all resources, including sildenafil.
The investigators concluded that the cost-effectiveness of transferring prescribing responsibility in cases of severe distress from specialists to general practitioners remained to be determined. In a study on the containment of costs by the implementation of the Department of Health guidelines, following the introduction of sildenafil in Portsmouth and South East Hampshire, researchers observed that specialist care and associated costs fell by 70% in the first year following the introduction of the Department of Health guidelines, 54 Shabsigh whereas prescribing costs of primary care doubled. Overall costs for providing services in 1999 to 2000 were £232,169 compared to overall costs of £225,108 (uplifted to 1999– 2000 values) incurred in 1998 to 1999 (38). These studies indicate that costs can be contained despite the escalation in the number of patients. Potential benefits of the impact of introducing oral treatment for ED have been reported (39,40). Health care systems have generally rejected treatment of ED, despite ignorance regarding the effect of nontreatment (41,42).
Quality of Life General and disease-specific quality of life in men with diseases such as cancer of the prostate and end-stage renal disease have been evaluated and reported (43–49). In a multicenter European study of men with organic ED, self-administration of intra-urethral prostaglandin E1 (MUSE) resulted in a 70% improvement in the quality of erections, a 34% improvement in relationships with partners, and statistically significant improvements in personal wellness, contentment, and self-esteem, which translates indirectly to an improvement in quality of life (50). Intracavernosal injection of prostaglandin E1 also resulted in significant improvement, as measured by the Life Satisfaction Checklist (51).
According to the Life Satisfaction Checklist, it was possible to differentiate between patients with organic, psychogenic, and no ED. The study indicated that sexual satisfaction was a major indicator for general life satisfaction. In two further studies of intracavernous injection for ED, a large percentage of patients indicated that treatment improved quality of life (52,53). Most reports from studies on various aspects of quality of life in patients with ED, such as the International Index of Erectile Function (question 13, overall satisfaction with sex life, and question 14, sexual relationship with partner), the Erection Distress Scale, and the Psychlogical General Well-Being Index, showed improvements in quality of life. However, it was unclear why some instruments as measures of self-control and anxiety, such as the Rosenburg Self-Esteem Scale and the Medical Outcome Study, did not detect improvement in quality of life (54–57). Most studies have limited and diverse quality-of-life measurements, but they all support the notion that therapy for ED improves quality of life.
Relationship Improvement in the quality of life in patients affects their partners. In studies where partners were assessed about their responses, they responded equally as well to treatment and reported significant increases in intercourse frequency, sexual arousal, orgasm, and overall sexual satisfaction (58). The mental and social domains, as measured by the Duke Health Profile, improved significantly after intracavernosal injection of prostaglandin E1 as treatment for ED (59). A 34% improvement in “relationship with partner” domain was reported in a multicenter European study of 249 men with organic ED who were treated with self-administered transurethral alprostadil (58).
Comorbid Conditions Comorbid conditions affect erectile function and quality of life negatively, and treatments of these conditions usually improve erectile function and quality of life. Interestingly, symptomatic treatment of ED with sildenafil resulted in an improvement of depression, as measured by depressive scales (60).