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

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.

Key Words: prostate, prostatic hyperplasia, drug therapy, combination, tamsulosin, dutasteride

Abbreviations and Acronyms: 5-ARI, 5α-reductase inhibitor, AUR, acute urinary retention, BPH, benign prostatic hyperplasia, CombAT, Combination of Avodart and Tamsulosin, I-PSS, International Prostate Symptom Score, LUTS, lower urinary tract symptoms, MTOPS, Medical Therapy of Prostatic Symptoms, PSA, prostate specific antigen, Qmax, peak urinary flow, TRUS, transrectal ultrasound