Roehrborn, C. G. et al. The effects of combination therapy with dutasteride and tamsulosin on clinical outcomes in men with symptomatic benign prostatic hyperplasia: 4-year results from the CombAT study. Eur. Urol. 55, 461–471 (2009).

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A study of nearly 5,000 men with lower urinary tract symptoms (LUTS) secondary to benign prostatic hyperplasia (BPH) has shown that treatment with dutasteride plus tamsulosin is superior to monotherapy in the long term. “Combination therapy results in earlier improvement in symptoms and flow rate compared to monotherapy, preventing acute urinary retention in high-risk patients and enabling them to avoid surgery,” comments lead author Claus Roehrborn.

Combined regimens are known to improve patient-reported outcomes. This multicenter trial focused on hard clinical end points—time to first episode of acute urinary retention or BPH-related surgery—in a 4,844-strong cohort of patients with LUTS rated as moderate or severe. Compared with a tamsulosin plus placebo regimen, daily doses of tamsulosin (0.4 mg) plus dutasteride (0.5 mg) for 4 years significantly prolonged time to primary end point attainment. Combination therapy was not, however, superior to dutasteride plus placebo. The relative risk of clinical and symptomatic progression was reduced by administration of both drugs, relative to monotherapy with either.

The superiority of combination therapy over tamsulosin alone was evident after 8 months, persisting and becoming more pronounced over the following 40 months. This is in contrast to the results of previous trials; the Veterans Affairs Cooperative and PREDICT studies failed to detect superiority of combination therapy after 12 months, and superiority emerged during the MTOPS trial only after 4–5 years. “Our study—the CombAT trial—enrolled patients at risk, with larger gland sizes and higher PSA values. This explains the difference between our results [and those of] MTOPS,” notes Roehrborn.