Cost-effectiveness of dutasteride-tamsulosin combination therapy for the treatment of symptomatic benign prostatic hyperplasia: A Canadian model based on the CombAT trial

Introduction: Benign prostatic hyperplasia (BPH) is common in men 50 years old and older. The main treatment options are alpha-blockers (such as tamsulosin), which reduce symptoms, and 5-alpha reductase inhibitors (such as dutasteride), which reduce symptoms and slow disease progression. Clinical studies have demonstrated that dutasteride-tamsulosin combination therapy is more effective than either monotherapy to treat symptomatic BPH. We studied the cost-effectiveness in Canada of the dutasteride (0.5 mg/day) and tamsulosin (0.4 mg/day) combination compared with tamsulosin or dutasteride monotherapy. Methods: A Markov model was developed which follows a cohort of male BPH patients >= 50 with moderate to severe lower urinary tract symptoms (LUTS). The model estimates costs to the Canadian health care system and outcomes (in terms of quality adjusted life years [QALYs]) at 10 years and over a patient's lifetime. The dutasteride-tamsulosin combination was compared to each of tamsulosin monotherapy and dutasteride monotherapy. Results: Compared with tamsulosin, the combination was more costly and produced better patient outcomes. Over a lifetime, the incremental cost-effectiveness ratio was CAN$25 437 per QALY gained. At a willingness to pay CAN$50 000 per QALY, the probability of combination therapy being cost-effective was 99.6%. Compared with dutasteride, the combination therapy was the dominant option from year 2, offering improved patient outcomes at lower cost. The probability that combination therapy is more cost-effective than dutasteride was 99.8%. Conclusion: Combination therapy offers important clinical benefits for patients with symptomatic BPH, and there is a high probability that it is cost-effective in the Canadian health care system relative to either monotherapy.