Here is the design of a clinical trial:

Official Title: Transcutaneous Tibial Nerve Stimulation in Patients with Acute Spinal Cord Injury to Prevent Neurogenic Detrusor Overactivity: a Nationwide Randomised, Sham-controlled, Double-blind Clinical Trial

Included conditions:
- Spinal Cord Injury, Acute

Study Armgroups:
- {'label': 'VERUM transcutaneous tibial nerve stimulation (TTNS)', 'type': 'EXPERIMENTAL', 'interventionNames': ['Device: VERUM TTNS']}
- {'label': 'SHAM transcutaneous tibial nerve stimulation (TTNS)', 'type': 'SHAM_COMPARATOR', 'interventionNames': ['Device: SHAM TTNS']}

Interventions:
- {'type': 'DEVICE', 'name': 'VERUM TTNS', 'description': '* Daily 30-minute TTNS intervention is performed 5 days a week during a treatment period of 6-9 weeks, until 3-month post assessments\n* During a preparation phase of several minutes, sensory and motor thresholds are assessed and stimulation intensities are adjusted for the following 30-minute treatment phase', 'armGroupLabels': ['VERUM transcutaneous tibial nerve stimulation (TTNS)']}
- {'type': 'DEVICE', 'name': 'SHAM TTNS', 'description': '* Daily 30-minute SHAM intervention is performed 5 days a week during a treatment period of 6-9 weeks, until 3-month post assessments\n* During a preparation phase of several minutes, sensory and motor thresholds are assessed and stimulation intensities are adjusted for the following 30-minute treatment phase', 'armGroupLabels': ['SHAM transcutaneous tibial nerve stimulation (TTNS)']}

Primary Outcomes:
- {'measure': 'The occurrence of neurogenic DO jeopardizing the upper urinary tract', 'description': 'Defined as composite measure: Urodynamic assessment establishing DO amplitude ≥40 cmH2O; or else initiation of DO treatment (with antimuscarinics and/or intradetrusor onabotulinumtoxinA injections)', 'timeFrame': 'up to 12 months after SCI'}

Please estimate the sample size based on the assumption: 
Power of 0.8, type I error probability of 0.05, and a continuity correction for binary outcome variable to avoid type I error inflation.
Sample size
        Presuming a proportion of spontaneous success among the sham group of 0.15,23 114 participants (57 verum, 57 sham) need to be included to detect a difference of 0.25 in the proportion of participants who develop NDO, and thereby to correctly reject the null hypothesis with a probability (power) of 0.8. The type I error probability associated with the test of this null hypothesis is 0.05. Since the primary outcome variable is binary, this sample size analysis included a continuity correction to avoid type I error inflation.
        Using prospective data collected by the SwiSCI inception cohort for the years 2014â2016 and applying a modified version of the TASCI inclusion/exclusion criteria, a total of 193 eligible patients are predicted during the 3-year recruitment period of TASCI. Anticipating a recruitment rate of 66%, this implies that the requisite 114 participants can be included within 3 years. Expected participant numbers per centre during the study period are 20 for Basel, 42 for Nottwil, 13 for Sion and 39 for ZÃ¼rich. Moreover, these data imply that participants who withdraw or drop out can be replaced.