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.