Predicting Risk of Urinary Incontinence and Adverse Events After Midurethral Sling Surgery in Women.

Objective: To construct and validate models that predict a patient's risk of developing stress and urgency urinary incontinence and adverse events 12 months after sling surgery.

Methods: This was a secondary analysis of four randomized trials. Twenty-five candidate predictors (patient characteristics and urodynamic variables) were identified from the National Institute of Diabetes and Digestive and Kidney Diseases Trial of Mid-Urethral Slings (N=597). Multiple logistic models were fit to predict four different outcomes: 1) bothersome stress urinary incontinence; 2) a positive stress test; 3) bothersome urgency urinary incontinence; and 4) any adverse event up to 12 months after sling surgery. Model discrimination was measured using a concordance index. Each model's concordance index was internally validated using 1,000 bootstrap samples and calibration curves were plotted. Final models were externally validated on a separate data set (n=902) from a combination of three different multicenter randomized trials.

Results: Four best models discriminated on internal validation between women with bothersome stress urinary incontinence (concordance index 0.728, 95% confidence interval [CI] 0.683-0.773), a positive stress test (concordance index 0.712, 95% CI 0.669-0.758), bothersome urgency urinary incontinence (concordance index 0.722, 95% CI 0.680-0.764), and any adverse event (concordance index 0.640, 95% CI 0.595-0.681) after sling surgery. Each model's concordance index was reduced as expected when important variables were removed for external validation, but model discrimination remained stable with bothersome stress urinary incontinence (concordance index 0.548), a positive stress test (concordance index 0.656), bothersome urgency urinary incontinence (concordance index 0.621), and any adverse event (concordance index 0.567). Predicted probabilities are closest to actual probabilities when predictions are less than 50%.

Conclusion: Four best and modified models discriminate between women who will and will not develop urinary incontinence and adverse events 12 months after midurethral sling surgery 64-73% and 55-66% of the time, respectively.