Why is erectile dysfunction so clinically important?

It is not always easy for men to discuss erectile dysfunction, but ED is a significant indicator of men's health and merits investigation and treatment

Erectile dysfunction (ED) is defined as the inability to attain and/or maintain an erection sufficient for sexual intercourse. It is estimated to affect 40% of men at the age of 40, and 67% of men at 70.1 Not only is ED important from the perspective of sexual function and wellbeing, but also because it is often associated with other serious diseases. (Box 1) ED may precede the diagnosis of cardiovascular diseases (CVD), including angina, myocardial infarction, stroke and transient ischaemic attack.² CVD and ED share many of the same risk factors — smoking, hypertension, hypercholesterolaemia, lack of exercise and obesity.² These risk factors are associated with the development of endothelial dysfunction, which affects the arteries supplying the penis just as much as the coronary arteries.

ED is also commonly associated with diabetes. Men with diabetes tend to develop ED at an earlier age than men who do not have diabetes,1 and their ED is often more severe and less responsive to conventional oral treatments. The association between the two conditions may be linked to a number of factors, including:3

• Macrovascular disease
• Microvascular disease
• Endothelial dysfunction
• Hyperlipidaemia
• Neuropathy
• Testosterone deficiency syndrome
• Depression

Because ED can be the presenting sign of many significant health problems, (Box 1) it is important that nurses routinely enquire about sexual function: men may not volunteer this information. If ED is diagnosed, risk factors for CVD and diabetes should be assessed and if the patient has CVD or diabetes, it is appropriate to ask about sexual function.

For men with suspected ED, initial evaluation should include a clear assessment of the nature of the sexual problem, including a full medical history — including current medication; focused physical examination; and appropriate investigations.

MEDICAL HISTORY

Careful history taking may reveal the cause of ED, or uncover other problems such as premature ejaculation, reduced libido or relationship issues. It may also identify psychiatric problems, including:

• Generalised anxiety states
• Depressive illness
• Psychosis
• Body dysmorphic disorder
• Gender identity issues

These conditions should be addressed before ED can be treated.

The checklist on page 12 may point to whether a patient's ED is caused by physical or psychological factors. (Table 1)

Current medication

Many commonly prescribed drugs can increase the risk of ED, including antihypertensives (diuretics, ß-blockers) and antidepressants:9 look for a temporal association between the initiation of drug therapy and the onset of ED. If the problem arose several years after the patient started on a diuretic, for example, their ED is less likely to be drug-related than if the ED coincided with the start of medication.

Excessive alcohol use can lead to long term ED, and also disorders of ejaculation or arousal. Other recreational drugs associated with ED include cocaine, heroin and methadone.⁹

Physical examination

It is important not to neglect a physical examination of men who present with suspected ED. A general physical examination should focus on any signs of systemic conditions associated with ED, in particular the presence or absence of normal secondary sexual characteristics.

One clear area of concern is cardiovascular disease and recent myocardial infarction or stroke: in such cases, sexual activity may not be appropriate without a full cardiovascular risk assessment, which may affect the treatments or advice that can be offered. Problems with mobility or manual dexterity may also be factors in ED.

Investigations

Some laboratory investigations are necessary in all men with ED, if not to reveal the cause of ED, then to assess risk factors for other conditions associated with ED, especially diabetes (fasting blood glucose) and CVD (fasting lipids).

Both the British Society of Sexual Medicine (BSSM)¹⁰ and the European Association of Urology11 recommend that testosterone levels should be measured routinely in men with ED. Up to one-in-three men with ED may have testosterone levels below normal.

TREATMENT OPTIONS

The management of ED has been transformed in the last decade since the introduction of oral PDE5 inhibitors. These are now well-established as first line treatments, despite continuing prescribing restrictions. Other therapeutic options are also available, including some that require specialist referral: consideration of these is warranted when oral therapies are contraindicated (e.g. men taking nitrates), ineffective due to aetiology of ED (e.g. spinal cord injury), or have become less effective (e.g. progression of diabetes). Patient choice is also an important consideration, and ED of psychogenic origin may respond to psychosexual therapy alone.

Available treatments for ED

• Oral PDE5 inhibitors: sildenafil (Viagra®), tadalafil (Cialis®), vardenafil (Levitra®)
• Transurethral pellet: alprostadil (MUSE®)
• Intracavernosal injection: alprostadil (Caverject®)
• Vacuum devices: manual or battery operated
• Penile prosthesis: surgical insertion of prosthetic corpus cavernosum
• Psychosexual therapy

All three PDE5 inhibitors are highly effective in the management of ED, with most studies showing success rates of 80% or higher.

There is good evidence that PDE5 inhibitors are effective in ED of various aetiologies and severities, and in the presence of comorbidities, including diabetes and hypertension, and following radical prostatectomy. They are considered the treatment of choice for most men with ED because of their efficacy and safety profiles, together with the convenience of oral administration. Since the launch of Viagra in 1988, media attention has led patients to have high — and sometimes unrealistic — expectations that PDE5 inhibitors are a universal 'cure' for ED.

However, not all men find that PDE5 inhibitor treatment is successful or that it is successful on every occasion.

Patients for whom treatment is initially unsuccessful should be encouraged to continue treatment for at least four doses, because the cumulative probability of success increases with additional doses. In patients who do not respond to PDE5 inhibitor therapy, the BSSM recommends:10

• Re-counselling on proper use
• Optimal treatment of concurrent disease and re-evaluation for new risk factors
• Treatment of concurrent low testosterone levels
• An alternative drug — occasionally patients may respond to one drug when another has failed
• More frequent dosing regimes

Approximately 25% of men with ED do not respond to PDE5-inhibitors alone. Factors predicting a poor response to treatment included uncontrolled diabetes, testosterone deficiency, current smoking and a low pre-treatment erectile function score. Addressing reversible risk factors, such as replacing testosterone, may increase the effectiveness of PDE5-inhibitor treatment.

CONCLUSION

ED becomes an increasingly common problem as men grow older, especially in those with diabetes or cardiovascular disease. Not only is it a symptom of these conditions, but can also be an early warning of their presence. Practice nurses can have a valuable role in enquiring about sexual function and encouraging patients to obtain help and treatment where it is needed. -

REFERENCES

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