Factors associated with percutaneous nerve evaluation and permanent sacral nerve modulation outcome in patients with fecal incontinence.

Purpose: Sacral nerve modulation is an established treatment for fecal incontinence. Little is known about predictive factors for successful percutaneous nerve evaluation (or test stimulation) and permanent sacral nerve modulation outcome. The purpose of this retrospective study was to discover predictive factors associated with temporary and permanent stimulation.
Methods: We analyzed data from test stimulations performed in patients with fecal incontinence from March 2000 until May 2007. Successful outcome was defined as >50% improvement of incontinence episodes in three weeks. Patients with a successful test stimulation were eligible for permanent sacral nerve modulation implantation. All patients who subsequently had permanent sacral nerve modulation were analyzed. Logistic regression was used to determine the predictive power of baseline demographics and diagnostic variables.
Results: Test stimulations were performed in 245 patients (226 females; mean age, 56.6 (standard deviation, 12.8) years). Our analysis showed that older age (P = 0.014), external anal sphincter defects (P = 0.005), and repeated procedures after initial failure (P = 0.001) were significantly related to failure. One hundred seventy-three patients (70.6%) were eligible for permanent sacral nerve modulation implantation. The analysis showed no significant predictive factors related to permanent sacral nerve modulation.
Conclusion: Three predictive factors were negatively associated with the outcome of test stimulation: older age, repeated procedures, and a defect in the external anal sphincter. These factors may indicate lower chances of success for test stimulation but do not exclude patients from sacral nerve modulation treatment. Although assessed in a selected patient group, no factors were predictive of the outcome of permanent stimulation.