Predictors of the outcome of percutaneous nerve evaluation for faecal incontinence

Background: The aim was to identify patient-related and operative factors that might predict the outcome of percutaneous nerve evaluation (PINE). Methods: Demographic data (age, sex, body mass index), primary cause of incontinence, number and type of incontinence episodes, results of endoanal ultrasonography and manometry, and operative factors from 244 patients who underwent PNE for faecal incontinence were reviewed. Each factor was assessed according to the outcome, and explored by univariable and multivariable analysis to identify predictors. Results: Some 191 patients (78.3 per cent) had a successful PNE. A low amplitude of sensory threshold during PNE (odds ratio (OR) 0.69 (95 per cent confidence interval 0.59 to 0.81); P < 0.001) and lead placement anterior to the sacral cortex (OR 9.06 (4.70 to 17.45); P < 0.001) were positive predictive factors for successful outcome of PNE. Neither a defect nor an abnormality of either the external (OR 0.88 (0.39 to 1.97); P = 0.749) or internal (OR 0.62 (0.27 to 1.42); P = 0.255) anal sphincter was a negative predictive factor. Demographic variables, number of incontinence episodes and the motor response threshold did not predict outcome. Conclusion: No preoperative predictor of PNE outcome could be identified. Predictors were limited to operative lead placement and sensory response during PINE.