The effects of dutasteride or tamsulosin alone and in combination on storage and voiding symptoms in men with lower urinary tract symptoms (LUTS) and benign prostatic hyperplasia (BPH): 4-year data from the Combination of Avodart and Tamsulosin (CombAT) study.

OBJECTIVE: • To assess the effects of combined therapy with dutasteride and tamsulosin on voiding and storage symptoms compared with those of dutasteride or tamsulosin alone, using 4-year data from the Combination of Avodart and Tamsulosin (CombAT) study.

PATIENTS AND METHODS: • Men (n = 4844) aged ≥ 50 years with moderate-to-severe lower urinary tract symptoms (LUTS) due to benign prostate hyperplasia (BPH), a prostate volume of ≥ 30 mL, and a serum prostate-specific antigen level of 1.5-10 ng/mL. • CombAT was a multicentre, double-blind, parallel-group study. • Oral dutasteride (0.5 mg) or tamsulosin (0.4 mg) alone or in combination was taken daily for 4 years. • Mean changes from baseline in storage and voiding symptoms at 4 years were assessed using subscales of the International Prostate Symptom Score.

RESULTS: •  At 4 years, the mean reduction in the storage subscore was significantly greater in the combined therapy group vs the dutasteride (adjusted mean difference -0.43) and tamsulosin (adjusted mean difference -0.96) monotherapy groups (P < 0.001). • Also at 4 years, the mean reduction in the voiding subscore was significantly greater in the combined therapy group vs the dutasteride (adjusted mean difference -0.51) and tamsulosin (adjusted mean difference -1.60) monotherapy groups (P < 0.001). • The improvement in the storage subscore with combined therapy was significantly better (P < 0.001) than dutasteride and tamsulosin from 3 months and 12 months, respectively. Similarly, the improvement in the voiding subscore with combined therapy was significantly better than dutasteride (P < 0.001) and tamsulosin (P ≤ 0.006) from 3 months and 6 months, respectively. • Improvements in the storage and voiding symptom subscores with combined therapy were achieved irrespective of prostate volume, although in men with the highest baseline prostate volumes (≥ 58 mL), combined therapy was not better than dutasteride.

CONCLUSIONS: • In men with a prostate volume of ≥ 30 mL, combined therapy with dutasteride plus tamsulosin provided better long-term (up to 4 years) control of both storage and voiding LUTS compared with tamsulosin monotherapy. • Combined therapy was better than dutasteride monotherapy in men with prostate volumes of ≥ 30 to < 58 mL, but not in men with a prostate volume of ≥ 58 mL.