Third-line treatment for overactive bladder: should mirabegron be tried before intravesical botulinum toxin A therapy?

Introduction and hypothesis Mirabegron is a new beta 3 agonist for the treatment of overactive bladder (OAB). Although there are extensive data from randomised controlled trials, there is little real world evidence about its effectiveness and side effects. We conducted a prospective cohort study to evaluate the effectiveness of mirabegron as third-line treatment in patients with refractory OAB who did not benefit from antimuscarinic therapy and bladder drill. Methods The study was a prospective consecutive cohort of 67 women treated with mirabegron 50 mg. All the patients had symptoms of urgency with or without urgency incontinence and had failed to improve with bladder drill and at least one antimuscarinic medication. The outcomes were assessed after 6 weeks using the International Consultation of Incontinence Modular Questionnaire Short Form (ICIQ-SF), Patient Global Impression of Improvement (PGI-I) scale and Kings Health Questionnaire (KHQ). Results The mean number of previous antimuscarinics was 2.81 (range 1–6). Forty out of 67 patients (60 %) described an improvement in their OAB. Responders demonstrated a significant improvement in 5 out of 10 domains of the KHQ. Similarly, the ICI-Q score improved from a mean of 12.7 (±5.3) to 9.2 (±5.3; p ≤ 0.008). Seven women (10 %) stopped mirabegron because of side effects. Conclusions This post-marketing surveillance study confirms that mirabegron improves clinical and quality of life outcomes in patients with OAB. The rate of side effects was low. This study supports mirabegron use as a third-line treatment for overactive bladder.