Does obesity impact the success of an InterStim test phase for the treatment of refractory urge urinary incontinence in female patients?

OBJECTIVES: Some providers believe obesity may be a relative contraindication for InterStim; however, the relationship between obesity and treatment outcome has not been evaluated. Our objectives were to compare the test phase (stage 1) success and complications of obese versus nonobese women undergoing a 2-stage InterStim procedure for refractory urge urinary incontinence (UUI). METHODS: We conducted a retrospective cohort study of obese and nonobese women who underwent stage 1 InterStim for refractory UUI. We compared the stage 1 success, defined as undergoing stage 2 generator implantation after demonstrating improvement of 50% or greater during test phase and intraoperative and postoperative complications within 1 year between obese and nonobese cohorts. RESULTS: Of 149 subjects, 80 (53.7%) were obese (body mass index, 37.3±5.87 kg/mg), and 69 (46.3%) were nonobese (body mass index, 25.6±2.82 kg/m). The overall stage 1 success was 81%. No statistically significant difference existed in stage 1 success between obese and nonobese cohorts (83% vs 78%, P=0.52). In a logistic regression model controlling for obesity, age, preoperative incontinence episodes per 24 hours, psychiatric diagnoses, arthritis, and diabetes mellitus, age per decade was the only variable significantly associated with stage 1 InterStim success (odds ratio, 0.61; 95% confidence interval, 0.39-0.96). Complications were also similar between cohorts (obese 20% vs nonobese 13%, P=0.26). CONCLUSIONS: In women undergoing staged InterStim therapy, stage 1 success and complications were similar between obese versus nonobese women. These data suggest that obesity should not be considered a limiting factor when determining whether a patient is a candidate for InterStim therapy for treatment of refractory UUI.