Mirabegron Add-On Tamsulosin for Men with Overactive Bladder Symptoms: A Pooled Analysis of Four Randomized Controlled Trials

Introduction: Overactive bladder symptoms (OABSs) affect patients' quality of life (QOL) worldwide. This pooled analysis compared the efficacy and safety of mirabegron add-on tamsulosin with those of tamsulosin add-on placebo in OABS treatment. Methods: PubMed, Embase, MEDLINE, and the Cochrane Controlled Trial Register databases were searched for randomized controlled trials (RCTs) examining the efficacy of mirabegron add-on therapy to tamsulosin in the treatment of OABS. Moreover, references from the selected studies were screened. Review Manager 5.4 was used to analyze data. Results: Four RCTs involving 1,397 patients with OABS were selected. Of the total, 697 patients receiving mirabegron add-on tamsulosin constituted the experimental group, and 700 patients receiving tamsulosin add-on placebo constituted the control group. The efficacy endpoints were as follows: mean number of micturition per day (mean difference [MD] = -0.26, 95% confidence interval [CI] = -0.41 to -0.10, p = 0.0001), urgency episodes per day (MD = -0.67, 95% CI = -1.02 to -0.32, p = 0.0002), urgency urinary incontinence (UUI) episodes per day (MD = -0.42, 95% CI = -0.66 to -0.19, p = 0.0005), mean volume voided/micturition (MD = 10.84, 95% CI = 4.97-16.71, p = 0.0003), total International Prostate Symptom Score (IPSS) (MD = -2.01, 95% CI = -4.02 to -0.01, p = 0.05), and IPSS QOL index (MD = -0.65, 95% CI = -0.94 to -0.35, p < 0.0001). Mirabegron therapy, an add-on therapy to tamsulosin, was effective in treating patients with OABS. Moreover, mirabegron might reduce the total IPSS (MD = -2.01, 95% CI = -4.02 to -0.01, p = 0.05). The safety endpoint, treatment-emergent adverse events (odds ratio = 0.94, 95% CI = 0.78-1.13, p = 0.49), suggested that although mirabegron was well-tolerated, it possibly increased the post-void residual urine volume (MD = 10.28, 95% CI = 1.82-18.75, p = 0.02). Conclusion: Combination therapy using mirabegron and tamsulosin may be effective in treating patients with non-neurogenic OABS in terms of UUI episodes, total IPSS, and IPSS QOL index. However, its effectiveness must be verified by analyzing additional factors for OABS through further RCTs.