Single Centre Randomised Pilot Study of Two Regimens (30mins Daily or Weekly for 12 Weeks) of Transcutaneous Tibial Nerve Stimulation of Patients With Overactive Bladder (OAB) Syndrome

In this single centre pilot study, 48 patients with OAB (24 with neurogenic and 24 with idiopathic OAB) were randomized to use a self-applicating ambulatory skin-adhering device to transcutaneously stimulate the tibial nerve for 30 minutes, either once daily or once weekly, for 12-weeks. Changes in lower urinary tract (LUT) OAB symptoms and QoL were measured at baseline, weeks 4, 8, and 12 using standardized validated scoring instruments (ICIQ-OAB and ICIQ-LUTSqol) and a Global Response Assessment (GRA) at week 12. Weekly phone calls and a usage diary captured patient-reported experiences with the device and compliance.

The primary study outcomes were to assess safety and acceptability of the device. In addition, treatment response was assessed using the Global Response Assessment (GRA) at week-12, and the International Consultation on Incontinence Questionnaire Overactive Bladder and LUTS-quality of life (ICIQ-OAB and ICIQ-LUTSqol) at baseline, week 4, 8 and 12. In the GRA patients were asked to assess their response to treatment using an ordinal scale of 0 to 3, referring to none, mild, moderate or marked improvement, respectively 1. Patients reporting moderate or marked improvement were considered to have responded to treatment 1. The ICIQ-OAB score is a 4-item questionnaire that assesses OAB symptom severity and bother whereas the ICIQ-LUTSqol score is a 20-item health related quality of life questionnaire. In both questionnaires, part A assesses symptom severity and part B reflects the accumulative bother to the patient. High scores suggests worse symptom profiles and negative impact on QoL, respectively.

Patients recorded use of the device in a customized compliance diary which also included entries for their experiences in using the device and any adverse effects. Additionally, weekly phone calls were made by a member of the research team to assess compliance.

Statistical analysis A feasibility sample size of 48 patients was adopted and no formal power calculation was performed as is the convention for pilot studies. All data were presented as means with SDs. Paired student t-tests were used to provide an estimate of within group responses between baseline and 12 weeks.