In female stress urinary incontinence (SUI) treated with mid-urethral slings (MUS), reducing morbidity and failure rate need assessing modifiable determinants related to surgical practice or sling properties (weight, elasticity). Clarifying whether surgical volume influences complication risk could inform potential regulation.
Our aim was to analyse the modifiable determinants of complications and recurrences based on known or identified risk factors in our registry, which was linked to health insurance data.

This analysis covers patients included in our registry  who received a midurethral sling for female stress urinary incontinence by the retropubic or transobturator route [1]. The data used in the main analysis were drawn from the registry [1] for the identification of the sling and from the health insurance database for the outcomes. Risk factors will be categorised into three domains (medical history / index surgery and characteristics of the implanted sling / surgical centre; see Table 1). 
A complication was defined as any surgical procedure to transect or remove the sling. A recurrence was defined as any further surgical procedure for urinary incontinence.
The explanatory analysis of surgical complications and recurrences is based on a Cox model with frailty, allowing for intra-centre correlation and the prioritisation of variables according to their individual level (level 1) or centre-related level (level 2, see Table 1). 
Prior to variables selection, a dimension reduction and variable pre-selection step is carried out using Principal Component Analysis performed for each domain. This will identify relevant combinations to include in the multivariate analyses and reduce the dimensionality of correlated variables, particularly those describing the characteristics of the sling. 
The analysis is conducted in three stages: 1) univariate models adjusted for age and the Charlson score for level 1 variables; 2) univariate models for centre (level 2) variables; 3) final multivariate model.

We identified 3,671 MUS insertions across 37 surgical centres between 2017 and 2020. The mean age of the women at surgery was 57 years. Eleven women were transferred to a continuous care unit following sling insertion; no deaths were reported during their hospital stay. The median follow-up period was 1,082 days (almost 3 years). The prevalence of complications leading to sectioning or removal of the sling was 4.0% (148/3671), and the prevalence of SUI recurrence requiring further surgery was 4.2% (156/3671). 
Level 1 univariate analyses (patient characteristics, sling properties and surgical procedure) showed that the following variables significantly increased the risk of complications: chronic disease, a history of surgery for SUI or POP, continue use of pain medication, the retropubic route, the weight and the elasticity of the sling. 
The following variables increased the risk of recurrence: the woman’s age at surgery, a history of surgery for SUI or POP, the retropubic route, and associated surgical procedures (hysterectomy or prolapse repair).
Further multivariate analyses are currently underway and will be presented at the congress.

Our work in routine clinical practice should help to identify the modifiable risk factors for complications and recurrence.

Our analysis could help to inform patients, guide the choice of surgical unit and regulate surgical activity.

Armengaud et al. Serious complications and recurrences after retropubic versus transobturator midurethral sling procedures for 2682 patients in the VIGI-MESH register. Am J Obstet Gynecol 2024;230:428.e1-428.e13. doi: 10.1016/j.ajog.2023.11.124
Bannay et al. The Best Use of the Charlson Comorbidity Index With Electronic Health Care Database to Predict Mortality. Med Care 2016;54:188–94.