The effects of dutasteride, tamsulosin and combination therapy on lower urinary tract symptoms in men with benign prostatic hyperplasia and prostatic enlargement: 2-year results from the CombAT study

J Urol. 2008 Feb;179(2):616-21; discussion 621. doi: 10.1016/j.juro.2007.09.084. Epub 2007 Dec 21.


Purpose: We investigated whether combination therapy with dutasteride and tamsulosin is more effective than either monotherapy alone for improving symptoms and long-term outcomes in men with moderate to severe lower urinary tract symptoms and prostatic enlargement (30 cc or greater). We report preplanned 2-year analyses.

Materials and methods: The CombAT study is an ongoing, multicenter, randomized, double-blind, parallel group study. Men 50 years or older with a clinical diagnosis of benign prostatic hyperplasia, International Prostate Symptom Score 12 points or greater, prostate volume 30 cc or greater, total serum prostate specific antigen 1.5 ng/ml or greater to 10 ng/ml or less and peak urinary flow greater than 5 to 15 ml per second or less with a minimum voided volume of 125 ml or greater were randomized to 0.5 mg dutasteride, 0.4 mg tamsulosin or the combination once daily for 4 years. Symptoms were assessed every 3 months and peak urinary flow was assessed every 6 months. The primary end point at 2 years was the change in International Prostate Symptom Score from baseline.

Results: Combination therapy resulted in significantly greater improvements in symptoms vs dutasteride from month 3 and tamsulosin from month 9, and in benign prostatic hyperplasia related health status from months 3 and 12, respectively. There was a significantly greater improvement from baseline in peak urinary flow for combination therapy vs dutasteride and tamsulosin monotherapies from month 6. There was a significant increase in drug related adverse events with combination therapy vs monotherapies, although most did not result in the cessation of therapy.

Conclusions: In men with moderate to severe lower urinary tract symptoms and prostate enlargement (30 cc or greater) combination therapy provides a significantly greater degree of benefit than tamsulosin or dutasteride monotherapy.

Publication types

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

MeSH terms

  • Adrenergic alpha-Antagonists / administration & dosage*
  • Aged
  • Azasteroids / administration & dosage*
  • Double-Blind Method
  • Drug Therapy, Combination
  • Dutasteride
  • Enzyme Inhibitors / administration & dosage*
  • Follow-Up Studies
  • Humans
  • Male
  • Middle Aged
  • Prostatic Hyperplasia / complications*
  • Prostatic Hyperplasia / pathology
  • Prostatic Hyperplasia / physiopathology
  • Sulfonamides / administration & dosage*
  • Tamsulosin
  • Time Factors
  • Treatment Outcome
  • Urination Disorders / drug therapy*
  • Urination Disorders / etiology
  • Urination Disorders / physiopathology


  • Adrenergic alpha-Antagonists
  • Azasteroids
  • Enzyme Inhibitors
  • Sulfonamides
  • Tamsulosin
  • Dutasteride