A randomized controlled study of the efficacy of tadalafil monotherapy versus combination of tadalafil and mirabegron for the treatment of persistent overactive bladder symptoms in men presenting with lower urinary tract symptoms (CONTACT Study)

AIM: To evaluate efficacy and safety of combination of tadalafil + mirabegron for overactive bladder/benign prostatic hyperplasia (OAB/BPH). METHODS: Male patients with lower urinary tract symptoms (50 to 89 years), with remaining OAB symptoms even after administering tadalafil for more than 8 weeks were randomly assigned to either tadalafil monotherapy group (5 mg/day) or tadalafil/mirabegron combination therapy group (5 mg/50 mg/day). The primary endpoint was change from baseline in total OAB symptom score (OABSS) at week 12. The secondary endpoints were changes in International Prostate Symptom Score (IPSS), NIH‐chronic prostatitis symptom index (NIH‐CPSI), and micturition chart parameters at weeks 4 and 12. RESULTS: A total of 176 patients were randomized to either monotherapy (87 patients) or combination therapy (89 patients). The baseline characteristics of patients in the two groups were similar. The total OABSS (95% confidence interval) of combination therapy was significantly decreased by 1.78 (1.05‐2.50) points compared with that of monotherapy (P < .001). Changes from baseline in OABSS nighttime voiding score, urgency score, urgency incontinence score, IPSS storage subscores, NIH‐CPSI total score, and numbers of voids, nighttime‐voids, and urgency episodes/day in micturition chart were significantly reduced in combination therapy (all P < .001). Patient‐reported outcome was significantly more satisfactory in combination therapy than in monotherapy (P < .001). One moderate adverse event (pain in hip joint) with hardly presumed causal relationship with therapy and seven mild adverse events were noted in monotherapy and combination therapy group, respectively. CONCLUSIONS: The effect of tadalafil/mirabegron combination therapy on relieving OAB symptoms appeared to be greater than that of tadalafil monotherapy and can be safely used.