Background: To investigate the long-term efficacy and safety of sildenafil for patients with erectile dysfunction (ED).
Methods: Between March 1999 and February 2001, a total of 3168 patients visited Taipei Veterans General Hospital for prescription of sildenafil. The follow-up period was 1-3 years. A questionnaire was designed for evaluation of efficacy and safety of sildenafil via telephone survey.
Results: Of the 3168 patients, 1414 were interviewed by telephone. Data from telephone questionnaires were successfully obtained in 1074 cases. Achievement of the first penile erection after sildenafil was reported in 58.8% of our patients. The distribution of the first doses was 0.6%, 8.5%, 81.9% and 90% for 12.5 mg, 25 mg, 50 mg and 100 mg, respectively. After administration of sildenafil, 72.1% men had successful intercourses "sometimes" or "always achieving vaginal penetration", and 72.3% had "slight difficulty" or "no difficulty" in maintaining of sexual intercourses. The "sometimes/most times/always" satisfaction accounted 63.9% and 62.8%, respectively for patients and partners. The global assessment of penile erection was improved in 58.6% of the patients. The sexual confidence of the patients was moderate, high and very high in 72.4% of the patients. Of the 434 patients who failed first penile erections, 400 (92.2%) were related to improper administration of sildenafil. Discontinuation of sildenafil in the last 3 months before telephone survey was found in 852 patients (80.2%). The causes of discontinuation were loss of efficacy in 51.6% of patients, lack of sexual desire in 8.8%, and chronic diseases in 8.2%. Spontaneous erection without sildenafil was claimed in 21.5% of the patients (most times in 9.5% and always in 12.0%). The rate of adverse events after taking sildenafil were 16.6%, and the most common adverse event was facial flushing (9.2%).
Conclusions: The results of this study demonstrated that the efficacy of sildenafil was similar to the previous clinical trials. The adverse events after sildenafil were mild and tolerable. Recovery of complete or partial spontaneous erection was noted in some patients (21.5% in our study) after long-term usage of sildenafil.