Baseline urodynamic predictors of treatment failure 1 year after mid urethral sling surgery

Abstract

Purpose: We determined whether baseline urodynamic study variables predict failure after mid urethral sling surgery.

Materials and methods: Preoperative urodynamic study variables and postoperative continence status were analyzed in women participating in a randomized trial comparing retropubic to transobturator mid urethral sling. Objective failure was defined by positive standardized stress test, 15 ml or greater on 24-hour pad test, or re-treatment for stress urinary incontinence. Subjective failure criteria were self-reported stress symptoms, leakage on 3-day diary or re-treatment for stress urinary incontinence. Logistic regression was used to assess associations between covariates and failure controlling for treatment group and clinical variables. Receiver operator curves were constructed for relationships between objective failure and measures of urethral function.

Results: Objective continence outcomes were available at 12 months for 565 of 597 (95%) women. Treatment failed in 260 women (245 by subjective criteria, 124 by objective criteria). No urodynamic variable was significantly associated with subjective failure on multivariate analysis. Valsalva leak point pressure, maximum urethral closure pressure and urodynamic stress incontinence were the only urodynamic variables consistently associated with objective failure on multivariate analysis. No specific cut point was determined for predicting failure for Valsalva leak point pressure or maximum urethral closure pressure by ROC. The lowest quartile (Valsalva leak point pressure less than 86 cm H2O, maximum urethral closure pressure less than 45 cm H2O) conferred an almost 2-fold increased odds of objective failure regardless of sling route (OR 2.23, 1.20-4.14 for Valsalva leak point pressure and OR 1.88, 1.04-3.41 for maximum urethral closure pressure).

Conclusions: Women with a Valsalva leak point pressure or maximum urethral closure pressure in the lowest quartile are nearly 2-fold more likely to experience stress urinary incontinence 1 year after transobturator or retropubic mid urethral sling.

Trial registration: ClinicalTrials.gov NCT00325039.

Figure 1

Receiver Operator Curves (ROC) for objective failure for VLPP and MUCP values. Horizontal and vertical lines in the lower left of each part depict the sensitivity and 1-specificity when using lower quartile cut-points for the urethral function values (86 cm H₂O for VLPP, 45 cm H₂O for MUCP).

Figure 2

Objective failure rates of retropubic and transobturator mid urethral sling procedures. In each part failure rates are stratified by urethral function measures in upper 3 quartiles (light gray) or lower quartile (dark gray). Error bars represent ± 1 standard error. Low VLPP is associated with higher objective failure rates (p=0.003), which holds for both treatment groups (interaction between treatment and VLPP not significant, p= 0.64). Low MUCP is associated with higher objective failure rates (p=0.003), whilch holds for both treatments groups (interaction between treatment and MUCP not significant, p=0.19).