The effect of finasteride on the risk of acute urinary retention and the need for surgical treatment among men with benign prostatic hyperplasia. Finasteride Long-Term Efficacy and Safety Study Group

N Engl J Med. 1998 Feb 26;338(9):557-63. doi: 10.1056/NEJM199802263380901.


Background: Finasteride is known to improve urinary symptoms in men with benign prostatic hyperplasia, but the extent to which the benefit is sustained and whether finasteride reduces the incidence of related events, including the need for surgery and the development of acute urinary retention, is not known.

Methods: In this double-blind, randomized, placebo-controlled trial, we studied 3040 men with moderate-to-severe urinary symptoms and enlarged prostate glands who were treated daily with 5 mg of finasteride or placebo for four years. Symptom scores (on a scale of 1 to 34), urinary flow rates, and the occurrence of outcome events were assessed every four months in 3016 men. Prostate volume was measured in a subgroup of the men. Complete data on outcomes were available for 2760 men.

Results: During the four-year study period, 152 of the 1503 men in the placebo group (10 percent) and 69 of the 1513 men in the finasteride group (5 percent) underwent surgery for benign prostatic hyperplasia (reduction in risk with finasteride, 55 percent; 95 percent confidence interval, 41 to 65 percent). Acute urinary retention developed in 99 men (7 percent) in the placebo group and 42 men (3 percent) in the finasteride group (reduction in risk with finasteride, 57 percent; 95 percent confidence interval, 40 to 69 percent). Among the men who completed the study, the mean decreases in the symptom score were 3.3 in the finasteride group and 1.3 in the placebo group (P<0.001). Treatment with finasteride also significantly improved urinary flow rates and reduced prostate volume (P<0.001).

Conclusions: Among men with symptoms of urinary obstruction and prostatic enlargement, treatment with finasteride for four years reduces symptoms and prostate volume, increases the urinary flow rate, and reduces the risk of surgery and acute urinary retention.

Publication types

  • Clinical Trial
  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • 5-alpha Reductase Inhibitors*
  • Aged
  • Double-Blind Method
  • Enzyme Inhibitors / adverse effects
  • Enzyme Inhibitors / pharmacology
  • Enzyme Inhibitors / therapeutic use*
  • Finasteride / adverse effects
  • Finasteride / pharmacology
  • Finasteride / therapeutic use*
  • Humans
  • Incidence
  • Male
  • Middle Aged
  • Prostate / drug effects
  • Prostate / pathology
  • Prostatic Hyperplasia / complications
  • Prostatic Hyperplasia / drug therapy*
  • Prostatic Hyperplasia / physiopathology
  • Prostatic Hyperplasia / surgery
  • Urinary Retention / epidemiology
  • Urinary Retention / etiology
  • Urinary Retention / prevention & control
  • Urination / drug effects


  • 5-alpha Reductase Inhibitors
  • Enzyme Inhibitors
  • Finasteride