Posterior Tibial Nerve Stimulation (PTNS) Plus Mirabegron to Treat Refractory OAB Symptoms (PTNS-M Study)

Specific Aims:

Introduction/Background: Urgency Urinary Incontinence (UUI) remains a challenging clinical problem for urogynecologists as they treat women and seek to find better therapies. There is a wealth of literature addressing individual therapies for first, second, and third line treatments for UUI. There are three main third line treatment options for UUI including percutaneous tibial nerve stimulation (PTNS), sacral neuromodulation, and intradetrusor botox. At the current time, there are limited studies that have looked at a combination of second and third-line therapy therapies for UUI. While some anticholinergic medications have been studied in combination with percutaneous tibial nerve stimulation (PTNS) such as solifenacin, tolterodine, and trospium, there is limited data on the combination of mirabegron, a beta-3 agonist, and PTNS for treatment of refractory UUI. The studies that looked at anticholinergic medications in combination with PTNS revealed improvement in UUI compared to PTNS plus placebo. However, there are patients who do not tolerate anticholinergic medications well because of side effects. A relatively new finding as reported by the American Urogynecologic Society (AUGS) about avoiding anticholinergic medications in women greater than age 70 secondary to increased risk for cognitive impairment, dementia, and Alzheimer's disease is further impetus to conduct this trial [1]. The rationale for studying mirabegron in combination with PTNS versus PTNS plus placebo is important as mirabegron does not have the significant side effect profile that anticholinergic medications have and better tolerated in the older population. Therefore, more research should be performed to evaluate the effect of the combination of mirabegron and PTNS for refractory UUI. The purpose of this study is to evaluate the combination of PTNS and mirabegron and compare that to PTNS plus placebo in the treatment of refractory UUI.

Hypothesis: Combination therapy of PTNS and mirabegron, a beta-3 agonist, will contribute to greater improvement in the number of urgency urinary incontinence episodes as measured by a 3-day bladder diary compared to PTNS plus placebo in women.

Method: This is a randomized clinical trial comparing the efficacy of combination therapy with PTNS plus mirabegron to PTNS plus placebo in women with refractory urgency urinary incontinence.

Primary Aim: The primary aim of this study is to compare the efficacy of combined treatment of PTNS and mirabegron versus PTNS plus placebo on change in the number of UUI episodes at 12 weeks.

Secondary Aims:

• Comparing urinary symptom specific distress and quality of life over a 12-week course of PTNS.
• Comparing the side effect/adverse event profile of combined treatment of PTNS and mirabegron versus PTNS plus placebo over a 12-week course of PTNS
• Comparing the treatment efficacy and adverse events of combined treatment of PTNS and mirabegron versus PTNS plus placebo in women > 70 years of age as a sub analysis within the study

Inclusion criteria

• Female patients > 18 years old at UAB facilities with refractory urgency urinary incontinence that have failed first line and second line treatments
• Ability to consent
• Ability to complete all study related items and interviews

Exclusion criteria

• Patients with a history of any known or determined urinary retention or urinary tract obstruction
• PVR > 150 ml in clinic prior to the start of PTNS
• History of bladder augmentation surgery
• Patients who are pregnant or who have the suspicion of pregnancy
• Uncontrolled hypertension
• Hypersensitivity to mirabegron
• Superficial and/or deep skin infection where PTNS intervention is required
• Spinal cord injury or clinically significant neurological disorders known to affect urgency urinary incontinence
• Bleeding diathesis
• Failure of previous third line treatment options such as sacral neuromodulation, PTNS, or Botox
• Pacemaker, implantable defibrillator
• Current use of Interstim sacral nerve stimulator or TENS in the pelvic region, back, or legs
• Coagulopathy
• Chronic swollen, infected, inflamed skin or skin eruptions (e.g., phlebitis, thrombophlebitis, varicose veins) in the region where the PTNS needles or surface electrodes would be placed
• Metal implant in foot/toes near TENS electrode location
• Marked sensory deficit (numbness) of feet or ankles in the region where the PTNS needles or surface electrodes would be placed
• Currently pregnant or planning to become pregnant during the course of the study
• Unwilling to use acceptable form of contraceptive if the participant is of childbearing potential
• Unable or unwilling to complete the 3-day bladder diary
• Visual impairment prohibiting reading the paper diary
• Inability to provide informed consent, complete questionnaires independently, or to attend intervention sessions
• Unable to speak, read, or write in English