Validity of a scored urological history in detecting detrusor instability in female urinary incontinence

Background. Kauppila and co-workers published in 1982 a detrusor instability score (DIS) for women with urinary incontinence. The aim of this study was to determine the validity of the DIS in an outpatient clinic for urogynecology. Methods. The DIS questionnaire was incorporated as part of an independent history at the first consultation. The DIS was compared with clinical diagnosis in 250 patients consecutively referred for evaluation. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and overall accuracy of the DIS in diagnosing genuine stress incontinence (GSI) were calculated using the gynecologist's clinical diagnosis based on urodynamic findings as the gold standard. An ROC-curve was constructed for determining the optimum cut-off point for the DIS for women with GSI. Results. A cut-off point at 7 for the DIS, yielded sensitivity=0.77, specificity=0.52, PPV=0.74, NPV=0.52 and an overall accuracy=0.68. Optimum cut-off point for GSI according to the ROC-curve was at a DIS-value of 5, yielding sensitivity=0.60, specificity=0.77, PPV=0.82, NPV=0.52 and overall accuracy=0.66. Conclusions. A cut-off point at 7 diagnosed 159 women (64%) as having GSI, 41 of them (16% of 250) having a false positive DIS. Similarly a cut-off point at 5 diagnosed 112 women (45%) as having GSI, 20 of them (8% of 250) having a false positive DIS. These women, if otherwise feasible and indicated, might perhaps undergo continence surgery without preoperative urodynamics. A lower cut-off point than originally proposed ought therefore to be used if the DIS is to become a useful preoperative tool for this kind of surgery.