Tension-free suburethral slings are one of the most common first-line surgical treatments for stress urinary incontinence. It is well known that biomechanical and biocompatibility properties of the materials used in the slings are related to their success and complication rates. Polyvinylidene fluoride (PVDF) has been proposed as an alternative to polypropylene (PP) for its use in suburethral slings. Owing to its biocompatibility and biomechanical properties it has been hypothesized that PVDF slings could be associated with less mesh-related complications. On the short term, PVDF has shown similar effectiveness to PP along with better safety prolife [1]. However, there are still no good-quality data on long-term outcomes comparing both materials.
The objective of this study is to describe and compare the effectiveness and complication rates of PVDF and PP transobturator suburethral tapes (TOT) in the long term.

We present the preliminary results of long-term follow-up from a multicentre RCT. Women were randomized to undergo PP or PVDF TOT. A block-randomization procedure, stratified by centre, was performed. Allocation to trial group was carried out by a central computer system. Commercial kits of Amid Type‐I PP‐TOTs used were those that each center used in their daily practice. The second material studied in TOTs was PVDF (DynaMesh‐SIS direct soft; FEG Textiltechnik).Women with pure stress urinary incontinence or stress-predominant mixed urinary incontinence were eligible. Postoperative long-term follow-up was performed at six to eight years as contemplated in the protocol of the study. Outcomes were classified as cured, improved or failed defined by composite objective and subjective criteria. The main outcome was the incidence of failure of the procedure. Sandvik’s and ICIQ-SF questionnaires were completed before and at last follow-up visit. Long-term complications are also reported. 
Normal distribution for continuous variables was assessed using the Shapiro–Wilk test. Quantitative variables were compared using the unpaired Student's t test and with the Mann–Whitney U test for those variables that did not follow a normal distribution. Categorical variables were analyzed using the χ2 test or Fisher's exact test when indicated. The incidence of failure was analyzed by means of the Kaplan–Meier survival function. Cox proportional hazard models were used to analyze the relation of basal characteristics and the incidence of failure of the procedure. A two‐tailed p value <0.05 was considered to indicate statistical significance. Ninety‐five percent confidence intervals (CI) were calculated. Outcomes analyses were performed on an intention‐to‐treat basis.

From the initial cohort of 285 randomized women, 190 have completed long-term follow-up: 94 women  from PP group and 96 from PVDF one. Cure-improvement rate at last follow-up in this cohort is 87.8% and 85.7% in the PP and PVDF groups respectively. The incidence of failure is similar between both groups (adjusted hazard ratio=0.702). Changes in questionnaires scores were also similar, however patients’ satisfaction at last follow-up, according to PGI-I questionnaire, seems slightly greater in the PVDF group (table 1), although differences are not statistically significant. We observe more long-term complications in the PP group: 18.3% with PP vs. 8.2% with PVDF (p=0.041), mainly owing to more cases of persistent long-term pain in the PP group. Complications are detailed in table 2.  
We find a similar rate of de novo urge-incontinence in both groups (PP=20.2% vs PVDF=16.3%; p=0.486). Reintervention rates owing to recurrent stress incontinence or to complications were also similar.

The interim data analysis of this RCT finds that PVDF has similar effectiveness than PP in the long-term, when used in TOTs. Objective, subjective and composite outcomes are similar regarding effectiveness. However, complication rates are higher in the PP group, mainly due to a greater number of cases of persistent pain. 
These results indicates that the material used in suburethral sling play a role in clinical outcomes and should be further investigated according to its relevance.

PVDF-TOTs show similar long-term effectiveness than PP with a lower complication rate. All these observations must be nevertheless taken with caution and should be corroborated with the final complete data analysis.

Sabadell J, Pereda-Núñez A, Ojeda-de-Los-Santos F, et al. Polypropylene and polyvinylidene fluoride transobturator slings for the treatment of female stress urinary incontinence: 1-Year outcomes from a multicentre randomized trial. Neurourol Urodyn 2021 Jan;40(1):475-482. DOI: 10.1002/nau.24586