Identifying Patients With Vesicovaginal Fistula at High Risk of Urinary Incontinence After Surgery

Abstract

Objective: To develop a risk score to identify women with vesicovaginal fistula at high risk of residual urinary incontinence after surgical repair.

Methods: We conducted a prospective cohort study among 401 women undergoing their first vesicovaginal fistula repair at a referral fistula repair center in Lilongwe, Malawi, between September 2011 and December 2014, who returned for follow-up within 120 days of surgery. We used logistic regression to develop a risk score to identify women with a high likelihood of residual urinary incontinence, defined as incontinence grade 2-5 within 120 days of vesicovaginal fistula repair, based on preoperative clinical and demographic characteristics (age, number of years with fistula, human immunodeficiency virus status, body mass index, previous repair surgery at an outside facility, revised Goh classification, Goh vesicovaginal fistula size, circumferential fistula, vaginal scaring, bladder size, and urethral length). The sensitivity, specificity, and positive and negative predictive values of the risk score at each cut point were assessed.

Results: Overall, 11 (3%) women had unsuccessful fistula closure. Of those with successful fistula closure (n=372), 85 (23%) experienced residual incontinence. A risk score cut point of 20 had sensitivity of 82% (95% confidence interval [CI] 72-89%) and specificity 63% (95% CI 57-69%) to potentially identify women with residual incontinence. In our population, the positive predictive value for a risk score cut point of 20 or higher was 43% (95% CI 36-51%) and the negative predictive value was 91% (95% CI 86-94%). Forty-eight percent of our study population had a risk score 20 or greater and, therefore, would have been identified for further intervention.

Conclusion: A risk score of 20 or higher was associated with an increased likelihood of residual incontinence with satisfactory sensitivity and specificity. If validated in alternative settings, the risk score could be used to refer women with a high likelihood of postoperative incontinence to more experienced surgeons.

Figures

Figure 1

Flowchart of study population of women with vesicovaginal and a measure of urinary incontinence within 120 days of fistula repair surgery.

Figure 2

Sensitivity and specificity at each risk score cut-point. The reference line at 20 indicates the risk score cut-point with sensitivity of >80% and specificity >60%.

Figure 3

Positive predictive value and negative predictive value for a risk score cut-point of 20, by prevalence. The reference line at 24% indicates the prevalence of residual incontinence in the study population.