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Why do patients with erectile dysfunction abandon effective therapy with sildenafil (Viagra®)?


This prospective study determined the rate of abandonment of sildenafil therapy and assessed the reasons for abandonment. Between January 2001 and December 2002, 234 patients with erectile dysfunction (ED) at three independent centers successfully began therapy with sildenafil 50 or 100 mg. The rate of noncompliance was 31%. A telephone survey of these patients was conducted to determine the reasons for abandonment. The majority reported that they had had no opportunity or desire for sexual intercourse or that their partners had shown no sexual interest. Few patients stated that the high cost of the medication or that adverse events were the cause.


Erectile dysfunction (ED) is defined as the inability to attain and/or maintain penile erection sufficient for satisfactory sexual performance.1

Oral phosphodiesterase 5 (PDE5) inhibitors such as sildenafil, vardenafil and tadalafil have become the treatment of choice for men with ED, with up to 73.8% of men in one study indicating a preference for oral treatment.2 These oral PDE5 inhibitors have proven to be efficacious in approximately 60–80% of unselected patients with ED. In a recent international survey of 27 838 men, the MALES study, 64% of men who had used sildenafil more than once reported being satisfied with this treatment.3,4 However, despite the reported efficacy of and satisfaction with sildenafil, long-term satisfaction with sildenafil use in patients initially satisfied with treatment have not yet been determined in a real-life situation.

The aim of this study was to determine the rate of abandonment of therapy in patients who had begun treatment with sildenafil and had reported good treatment efficacy, and to assess the reasons for abandonment of therapy.

Patients and methods

This prospective study included men with mixed ED longer than 6 months as defined by the WHO at three independent centers in Germany (private urologist's office, private general practitioner's office, outpatient clinic), who, from January 2001 to December 2002 (23 months) had begun oral therapy for their ED with sildenafil 50 or 100 mg. Examinations of the hormonal status (testosterone, prolactin) were not done in every patient. After receiving the first prescription (four tablets) patients were asked whether they have used the medication and whether or not they were able to successfully complete sexual intercourse more than once with vaginal penetration after intake. Those who answered positively were considered to have successfully begun medication with sildenafil.

Of a total of 234 patients included in the study, the etiology of ED was determined to be organic in nature in 202 (86%) of these patients. The mean age was 60.5 y, mean weight 86.5 kg and mean BMI 27.5 kg/m2. In all, 40% of the patients had hypertension, 51% were active or former smokers and 16% had diabetes. The mean IIEF Erectile Function (EF) Domain score was 17, indicating mild-to-moderate ED.

The rate of therapy abandonment of these patients was determined, with abandonment of therapy defined as not asking for a second prescription within 6 months of receiving the first prescription for sildenafil. Afterwards, the reasons for abandonment were determined by a telephone survey, in which the prescribing physician asked these patients to name the reasons why they had not asked for a new prescription of sildenafil.


Although treatment with sildenafil in these 234 patients had been determined to be successful, only 161 of these patients (69%) asked for a refill prescription within 6 months of receiving the first prescription. The remainder, 73 patients (31%), had not requested any refill within 6 months of receiving the first prescription, and were considered to have abandoned therapy.

Results of the telephone survey of the 73 patients who abandoned therapy are shown in Figure 1. In total, four (5%) patients were unable to be reached by telephone or by mail, three (4%) patients reported newly arisen relevant comorbid conditions (malignant tumors, hip prostheses), and one patient had died due to pancreatic carcinoma. Lack of opportunity or desire for sexual intercourse was cited as the reason for abandonment in 33 (45%) of the 73 patients, which resulted in them not having administered all of the doses in the first prescription. Overall, 19 (23%) patients reported that their partners had shown no sexual interest during this time frame. The high cost of the medication was given as the reason for abandonment in only nine (12%) patients. Adverse events such as headache and rhinitis were stated to be the cause of therapy abandonment by only four (5%) of the patients.

Figure 1

Reasons of abandonment of sildenafil therapy (n=73).


It has been estimated that in 1995 over 152 million men worldwide were affected with ED, and that in 2025 its prevalence worldwide will be approximately 322 million men.5 Men who experience ED may feel depressed, stressed, or anxious. The psychological consequences of erectile dysfunction are well documented.6

In a population-based studies, it was shown that the prevalence of ED was 19.2%, with prevalence increasing with increasing age.7 The proportion of men requiring such treatment for ED was highest in the age group 60–69 y.7 Public interest in sexual dysfunction, and ED in particular, has been increasing ever since the approval by the FDA in the USA of sildenafil (Viagra®) in 1998.8 Indeed, the coverage by the mass media of this indication and treatment after approval in the USA resulted in an increase in weekly doctors’ visits by men with the symptoms of this condition.8,9

The results of this and other studies, however, indicate that not only the amount of media coverage has an influence on patient behavior, but that other factors play a role in patient behavior. In the present study, approximately 30% of 234 patients with ED did not ask for a second prescription of sildenafil despite its efficacy, further illustrating that the need for treatment for ED is modulated by numerous outside factors. These patients tended to be older (mean age 62.7 y) and cited mainly situational and partner-related reasons for their abandonment. The high cost of the medication was a less important reason for noncompliance, substantiating findings from the Cologne study, in which almost half of the total sample were willing to pay 25 Euro per month for ED treatment, and 8% were willing to pay any amount.7 Side effects were rarely cited as the reason for the noncompliance, which is not surprising considering the favorable tolerability profile of this class of drugs.

Limitations of this study were the lack of a libido questionnaire and hormonal examinations before starting treatment with sildenafil. But our aim was to elucidate the reasons for the abandonment of a effective therapy with sildenafil in normal daily clinical practice. Further studies are necessary to focus on libido before and after a therapy with PDE5-inhibitors.

It is possible that the general increase in public awareness of sexual dysfunction and the availability of the PDE5 inhibitors, more convenient, noninvasive therapy for ED, led to many of the men in the current study to seek medical advice and successfully begin therapy, but that in approximately 30% of these men, factors not related to the actual condition led to abandonment of sildenafil treatment, despite the fact that it was efficacious in these men.

In addition, ‘abandonment’ as it was defined in this study included those who have cited lack of occasion (or desire) for sexual intercourse and so have a reduced frequency of administration and have not necessarily completely abandoned therapy, which is also the case for patients whose partners had shown no interest in sexual activity.

In the Cologne Study, when treatment need was defined as the co-occurrence of ED and dissatisfaction with one's sex life, 6.9% of men were determined to be in need of ED treatment, which is significantly less than the prevalence of ED (19.2%).7 This illustrates that not every man with sexual dysfunction experiences the distress and unhappiness leading to a need for therapy. However, the men in this study, who had all initiated treatment with sildenafil and then abandoned it, had been assured that an effective medication for their ED was available, in the case that they would like to engage in sexual activity. This may have effectively reduced the distress associated with their ED. After this, although, other factors may have begun to play a more important role in their therapy decisions, with a large proportion of these patients lacking the need to engage in sexual intercourse at all, or very rarely.

We conclude that a large proportion of patients with ED are satisfied with the knowledge that they have access to efficacious PDE5 inhibitors, even if they do not engage in sexual intercourse.


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We would like to thank Thomson Physicians World GmbH for their help in writing this manuscript.

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Correspondence to T Klotz.

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Klotz, T., Mathers, M., Klotz, R. et al. Why do patients with erectile dysfunction abandon effective therapy with sildenafil (Viagra®)?. Int J Impot Res 17, 2–4 (2005).

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  • erectile dysfunction
  • sildenafil
  • PDE5 inhibitor
  • therapy abandonment
  • compliance

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