Non-invasive Saphenous Nerve Stimulation Therapy for Overactive Bladder

The goal of this clinical trial is to study the NiNA System and how it works to treat overactive bladder. Up to 290 participants will be enrolled in the study in the USA and Australia. The investigational NiNA System includes a wearable neurostimulator device ("NiNA" or "Device"), a flexible wrap to secure the Device to the calf during treatment of the saphenous nerve (SAFN), with smartphone-based control application with patient support features that allow users to control the stimulation therapy and receive reminder on days they are supposed to provide therapy ("NiNA App") or an enhanced smartphone-based control application which also has patient support features and educational multi-media content ("NiNA Care App"). The main questions the study aims to answer are: 1) How does the NiNA system compare to a common overactive bladder (OAB) medication; 2) How well does the NiNA system improve overactive bladder symptoms; and, 3) Does the NiNA system produce any unwanted side-effects. In the study half the participants randomly receive the NiNA system and the other half first receive the OAB medication and later are treated with the NiNA System. The Participants in the investigative Device arm (NiNA) will: Provide NiNA system treatments very day for 30 minutes during a 28 day induction/restore period. This is followed by maintenance treatments (30 minutes, 3-times a week) until 12 weeks, when the primary endpoint data are measured. Participants continue maintenance (30 minutes, 3-times a week) for the remaining 52 weeks of the study. Participants in the OAB medication arm will: Take a capsule every day (tolterodine tartrate extended release (ER) 4 mg) for twelve weeks. At 12 weeks, OAB medication arm Participants will stop taking the OAB medication and cross-over to treatment with the NiNA system. One-third of the cross-over Participants will be use a phone-based software application that allows them to control the neurostimulator and receive reminders on days