Six-year follow up of silodosin monotherapy for the treatment of lower urinary tract symptoms suggestive of benign prostatic hyperplasia: What are the factors for continuation or withdrawal?

Objectives: To investigate the factors for continuation or withdrawal as an extension of a prospective study of silodosin monotherapy for the treatment of lower urinary tract symptoms suggestive of benign prostatic hyperplasia for more than 6 years. Methods: A total of 104 patients (age 71.5 +/- 8.2 years) were enrolled in the present study. The mean prostate volume was 44.1 +/- 23.9 mL. International Prostate Symptom Score, quality of life index, maximum flow rate, and postvoid residual urine volume were determined at baseline, and at 1, 3, 6 and 12-72 months after treatment. Results: Adverse events were noted in 14 patients (13.5%), and the most frequent adverse event was ejaculatory dysfunction (5.8%). Withdrawal was noted in 78 patients, and 26 patients (25.0%) were still taking silodosin at 72 months (continuing group). The reasons for withdrawals were: unknown in 27 patients (26.0%), adverse events in nine patients (8.7%), unsatisfactory effects in 30 patients (28.8%) and satisfied with the current condition for six patients (5.8%). In 30 patients who withdrew because of unsatisfactory effects, surgery was carried out in 21 patients (surgery group). The baseline total International Prostate Symptom Score did not differ between the continuing group and the surgery group. However, patients with the continuing group had significantly smaller baseline prostate volume, and lower baseline quality of life index and prostate-specific antigen, than in the surgery group. The mean total International Prostate Symptom Score, quality of life index and maximum flow rate improved significantly at 1 month, and remained stable up to 72 months. Conclusions: The withdrawal rate was higher in patients with a larger prostate. The effects of silodosin for lower urinary tract symptoms was immediate and stable up to 72 months.