Mirabegron as adjuvant treatment for patients with interstitial cystitis/bladder pain syndrome.

INTRODUCTION: Interstitial cystitis/bladder pain syndrome (IC/BPS) patients represent a heterogeneous group with pain and urinary storage symptoms and varying responses to current treatment options. The novel beta-3 agonist, mirabegron, has been shown to improve storage symptoms of patients with bladder overactivity; however, its effect on symptoms in the IC/BPS population has yet to be studied.

METHODS: Patients diagnosed at a single IC centre with IC/BPS undergoing standard therapy were treated with additional daily mirabegron 25 mg and seen in followup post-treatment. Patients completed the Interstitial Cystitis Symptom Index and Problem Index (ICSI/ICPI), and the Pelvic Pain and Urgency/Frequency Patient Symptom Scale (PUF) prior to and following mirabegron treatment. Global (NRS) and symptom-specific outcomes were assessed by comparing the pre- and post-treatment mean scores using tailed-t test (p<0.05 considered statistically significant).

RESULTS: A total of 23 patients were available for review pre- and post-mirabegron treatment. There was no significant difference in ICSI (p=0.448), ICPI (p=0.352), or PUF (p=0.869) pre- and post-treatment. Analysis of symptom-specific outcomes show statistically significant improvements in urgency (p=0.048); however, no statistically significant improvements in frequency (p=0.951) or pain (p=0.952) were observed with mirabegron therapy.

CONCLUSIONS: IC/BPS patients treated with mirabegron had improvement of urinary urgency, but no significant benefit in terms of pain or urinary frequency. This data suggests that mirabegron's role in the IC/BPS patient should be that of adjuvant treatment to ameliorate urgency.