Prospective Study of a Single Incision Sling vs. a Transobturator Sling in Women with Stress Urinary Incontinence: 3 Year Results

Abstract Background Long-term safety and efficacy data on use of single incision slings in stress urinary incontinence are limited. Objective Determine if the single incision sling Solyx (Boston Scientific, Marlborough, MA) is non-inferior to the transobturator sling Obtryx II (Boston Scientific, Marlborough, MA) in efficacy and safety for treatment of stress urinary incontinence. This 522 post-market surveillance study has been designed in response to an FDA request to evaluate improvement in stress urinary incontinence at 36 months following single incision sling compared to baseline, as well as provide an assessment of mesh-related complications and subject-reported outcomes, relative to the transobturator sling control. Study Design This prospective, non-randomized, parallel cohort, multi-center post-approval enrolled subjects to receive single incision sling or transobturator sling. Study sites were assigned to a cohort group based on documented competency with the cohort device. Patient follow-up was 36 months to compare efficacy and adverse events for noninferiority. Inclusion criteria included stress predominant urinary incontinence, a positive cough stress test, and post-void residual ≤ 150cc. Participants were ineligible if they had undergone prior stress urinary incontinence surgery or had a prior mesh complication. Primary endpoint was treatment success defined by composite negative cough stress test and subjective improvement in stress urinary incontinence using Patient Global Impression of Improvement at 36 months. Secondary endpoints included adverse events and indications for retreatment. Non-inferiority margins of 15% and 10% were prespecified for the primary efficacy and safety endpoints. Data analysis was performed using intent-to-treat and per protocol methods. Due to the observational nature of the study, a propensity score methodology was applied to account for differences in patient and surgeon characteristics between treatment groups. The study design and variables to be included in the propensity score model were reviewed and approved by FDA reviewers before outcome analyses were performed. Results No evidence of imbalance in baseline characteristics was observed between groups after propensity score stratification in the 281 subjects. Estimated blood loss (72.3 ± 92 vs. 73.1 ± 63.9 mL, p = 0.786), time to spontaneous void (1.1 ± 2 vs. 0.8 ± 2.8 days, p = 0.998), and time to discharge (0.7 ± 0.7 vs. 0.6 ± 0.6 days, p =0.524) were similar between groups. At 36 months, treatment success was 90.4% in the single incision sling group and 88.9% in the transobturator sling group (p = 0.93). At 36 months, mesh related complications were similar between groups (mesh exposure: 2.8% vs 5.0%, p=0.38). Serious adverse events including pain during intercourse (0.7% vs. 0%, p=1.00), pelvic pain (0.7% vs. 0%, p =1.00) and urinary retention (2.8% vs. 4.3%, p =0.54) were similar between groups. Conclusions Single incision sling was not inferior to transobturator sling for long-term treatment success of stress urinary incontinence. The rates of serious adverse events were acceptably low and similar between groups.