Design of Transurethral Bulking Agent Injection Versus Single-Incision Sling Trial

Transurethral bulking agent (TBA) injections and single incision slings (SIS) are low risk, minimally invasive options increasingly being used in the treatment of primary stress urinary incontinence (SUI); however, comparative trials are lacking.

We describe the study design and rationale for the Transurethral Bulking Agent Injection versus Single-Incision Sling for Stress Urinary Incontinence (BASIS) trial.

The study methods, inclusion criteria, assessments, safety and efficacy outcomes, and follow-up are reported. We also present methods for selection of surgical devices and public private partnerships for product donation. The engagement of anesthesia co-investigators to develop an office-based protocol is also described.

The BASIS trial is a multicentered, double-blind, randomized controlled, superiority study of up to 2 injections of TBA (Bulkamid) versus SIS (Solyx) at 12 months, with follow-up through 36 months. Women with primary, stress-predominant urinary incontinence without indication for general or regional anesthesia are eligible. A patient-centered primary outcome of Patient Global Impression of Improvement was used to calculate the sample size of 358. Secondary efficacy and safety outcomes of objective and subjective success, retreatment, and adverse events (including de novo pelvic floor muscle tenderness and dyspareunia), and cost-effectiveness analyses are planned. The feasibility of an office-based anesthesia protocol with sedation and local anesthesia will also be evaluated.

Results from the BASIS study will provide level 1 evidence on the comparative-effectiveness of 2 minimally invasive office-based treatments. Important safety data and 3-year outcomes will help clinicians and patients make informed decisions about primary SUI procedure options.