Better Classification Systems Needed for Genitourinary Fistulas

The current genitourinary fistula classification systems have poor to fair prognostic value, as does an empirically derived scoring system that predicts fistula closure 3 months after surgery, according to the findings of a new prospective cohort study.¹
   
The study sample included 1274 women from sub-Saharan Africa and Asia. Half the sample was used as a derivation cohort to create scoring systems that represented the 5 existing classification systems-developed by Lawson, Tafesse, Goh, Waaldijk, and the World Health Orgainization-and an empirically derived scoring system that was created by the study authors. The other half of the study sample was used as a validation cohort to test the scores. The primary study goal was to ascertain how well the current classification systems can predict fistula closure 3 months after surgery.
   
After determining which factors were significant predictors of failed closure in other classification systems and assessing factors that had predictive value for the failure of fistula closure but were not included in other classification systems, the researchers developed an empirically derived prognostic scoring system. This system was based on the following factors: more than 1 fistula, moderate or severe scarring, partial urethral involvement, and complete destruction of the urethra or transection/circumferential injury. The Lawson classification system was not included in the final analysis because only 1 component-mid-vaginal location-was significantly associated with repair outcome and at least 2 operating points are needed to establish an area under the curve (AUC).
   
Overall, none of the classification systems or the empirically derived prognostic scoring system had an AUC of more than 0.70, the baseline for good predictive accuracy. The Goh, Tafesse, and WHO classification systems and the empirically derived score had the highest predictive accuracy, but their corresponding AUCs were 0.63, 0.62, 0.60, and 0.62, respectively.
   
“The low AUCs suggest that factors other than fistula characteristics, such as surgeon’s skill or preoperative procedures and care, are at least as important in the determination of fistula closure,” wrote the study authors.¹
   
Additional assessment of the utility of the existing classification systems to predict fistula closure is needed, according to the study authors. They also suggest that these results highlight a need for a simple, easy-to-use, evidence-based prognostic score. Such a score could aid surgeons’ decision-making regarding patient triage and their surgical approach to planning the fistula repair. A standard score also could facilitate research efforts by making outcomes data more uniform across facilities.

Pertinent Points:
- Neither 4 tested classification systems for genitourinary fistula nor an empirically derived score developed by the study authors had good discriminatory value for predicting the prognosis of fistula repair 3 months after surgery.
- Existing classification systems could be simplified through the elimination of overlapping or nonpredictive components.
 

References:

1. Frajzyngier V, Li G, Larson E, et al. Development and comparison of prognostic scoring systems for surgical closure of genitourinary fistula. Am J Obstet Gynecol. 2013;208:112.e1-11.