Men with lower urinary tract symptoms (LUTS) treated with α-blockers (eg, tamsulosin) may experience overactive bladder (OAB) symptoms and receive add-on antimuscarinics. Mirabegron (a β3-adrenoreceptor agonist) is an alternative add-on therapy.
To evaluate the efficacy of mirabegron versus placebo in men with OAB symptoms receiving tamsulosin for LUTS.
Design, setting, and participants
Japanese and Korean men with OAB treated with tamsulosin for LUTS (January 2016–July 2017).
Single-blind, 4-wk screening: tamsulosin plus placebo orally once daily; double-blind, 12-wk treatment: patients randomized (n = 568) to mirabegron 50 mg or placebo, as add-on to tamsulosin.
Outcome measurements and statistical analysis
Primary endpoint: baseline to end of treatment (EoT) change in the mean number of micturitions/24 h, based on a 3-d voiding diary. Secondary endpoints: change in other diary variables and patient-reported outcomes from baseline to EoT. The primary endpoint was analyzed by analysis of covariance, including treatment group and region as fixed factors and baseline as a covariate.
Results and limitations
Mirabegron add-on therapy was superior to placebo in improving the primary endpoint (adjusted mean difference [95% confidence interval] vs placebo –0.52 [–0.82 to –0.21]) and secondary endpoints, including mean volume voided/micturition (12.08 [6.33–17.84]), OAB symptom score (–0.65 [–1.04 to –0.26]), International Prostate Symptom Score total (–1.19 [–1.94 to –0.44]), storage (–0.78 [–1.13 to –0.43]), quality of life scores (–0.29 [–0.51 to –0.07]), OAB symptom bother (–4.52 [–6.91 to –2.13]), and total health-related quality of life (2.79 [1.13 to 4.44]). Differences, compared with placebo, in urgency, urgency urinary incontinence, and nocturia were not statistically significant. Mirabegron was well tolerated, with no major safety concerns. Limitations included a lack of antimuscarinic comparison.
The mirabegron add-on therapy to tamsulosin for 12 wk in men with LUTS and OAB symptoms demonstrated superior efficacy to placebo and was well tolerated.