Comparison in the efficacy of fesoterodine or mirabegron add-on therapy to silodosin for patients with benign prostatic hyperplasia complicated by overactive bladder: A randomized, prospective trial using urodynamic studies

Aims To compare the efficacy of fesoterodine or mirabegron add-on therapy for persistent overactive bladder (OAB) symptoms despite silodosin monotherapy in men with lower urinary tract symptoms suggestive of benign prostatic hyperplasia, in both subjective and objective aspects. Methods A total of 120 patients with persistent OAB symptoms despite silodosin monotherapy were randomized to receive add-on therapy with fesoterodine (4 mg/day) or mirabegron (50 mg/day) for 12 weeks. At week 12, changes from baseline in patients' subjective symptoms and voiding/storage functions, as assessed using the International Prostate Symptom Score (IPSS), OAB symptom score (OABSS), and urodynamic studies, were compared between the groups. Results The final analysis included 50 and 52 patients in the fesoterodine and mirabegron groups, respectively. Although the IPSS and OABSS significantly improved in both groups, the fesoterodine (vs mirabegron) group showed significantly greater improvements in the OABSS-total (-2.8 vs -1.5, P = 0.004), IPSS-QOL (-1.5 vs -1.1, P = 0.04), and OABSS-urgency score (-1.5 vs -0.9, P = 0.008) at 12 weeks. Regarding storage functions, although both groups showed significant improvements, the fesoterodine group demonstrated greater improvements in the detrusor overactivity alleviation rate (52.6% vs 28.9%, P = 0.03). Voiding functions did not deteriorate in either group at 12 weeks; no significant inter-group differences were observed. Post-void residual urine significantly increased by 16 mL only in the fesoterodine group. Conclusion Add-on therapy of fesoterodine to silodosin was more effective than adding mirabegron to silodosin for improving OAB symptoms and storage functions, without deteriorating voiding symptoms or functions.