Hypothesis / aims of study
Single-incision midurethral slings (SIMS) were introduced with the aim of offering similar efficacy to transobturator suburetrhral tapes (TOT) with reduced morbidity for the treatment of female stress urinary incontinence (SUI). However, the effectiveness of SIMS in the long term is not well established. The objective of this study is to compare the long term effectiveness and complications of the SIMS Ajust™ and Align-TO™ transobturator tape.
Study design, materials and methods
We have performed a secondary analysis in a subset of patients from a multicentre randomized controlled trial. All patients attended at the coordinating centre were included in this analysis. Women with pure SUI or stress-predominant mixed urinary incontinence were eligible. The primary outcome was the cure/improvement rate at one year, defined by combined objective and subjective criteria. Initial sample size calculation was based on a cure rate of 90% for the reference procedure (full-length TOT), and a non-inferiority limit of - 15% was established based on previous literature and clinical relevance . Rate difference (RD) for cure/improvement with both procedures was calculated along with its 95% confidence interval. The Sandvik incontinence severity index and the International Consultation on Incontinence Questionnaire-Short Form (ICIQ-SF) were completed before surgery and at every follow-up visit. Complications were also reported.
In the present cohort 20 women were randomized to the SIMS Ajust™ and 19 to the TOT Align™. Both groups were similar regarding their initial characteristics (Table). The median follow-up was 48.5 months in the Ajust™ group and 56.3 months in the Align™ group. Regarding the main outcome at the last follow-up visit of every participant, 5 women were regarded as failures in the SIMS group (25%) while none (0%) in the TOT group. Of these failures 2 were because of SUI, 2 because severe de novo urge-incontinence and 1 because of mixed urinary incontinence. It could also be observed in the survival functions a higher incidence of failures in the SIMS group (Figure). Both the ICIQ-SF and Sandvik scores improved after the surgery with the standard TOT and the SIMS (score median difference-ICIQ: Ajust™ =-12 , Align™ =-14; score median difference-Sandvik: Ajust™ =-6.5 , Align™ =-8). The subjective improvement assessed with those questionnaires was similar in both groups (score difference, p between groups = 0.704 and 0.569 for the ICIQ-SF and Sandvik scores respectively). Two patients required a new surgery for recurrent SUI, all in the Ajust™ group. No intraoperative complications were observed in this cohort. Postoperative complication rates do not differ either between the two groups (Ajust™=6 (30%) vs. Align™=1 (5.3%); p=0.09). During the follow-up 4 women complaint of persistent pain in the Ajust™ group (20%) whilst one was reported in the Align™ one (5.3%), however those differences were not statistically significant (p=0.17). One case of the novo dyspareunia occurred and was related to an anchor vaginal displacement of the Ajust™ sling that was resolved by removing the anchor. No women were found to have an erosion of the sling during the follow-up period. Sling division was needed in one woman in the Align™ group owing to obstructive symptoms.
Interpretation of results
The present analysis is underpowered to establish a conclusion of inferiority of the SIMS Ajust™ compared with the Align™ TOT. However, the results seem to point that the effectiveness of the SIMS Ajust™ decreases over time more than that for standard TOTs. These observations should be confirmed with larger cohorts. In addition, similar to our short-term results , we have observed more cases of persistent pain in the Ajust™ group.