Receiver operating characteristic curves of symptom scores in the diagnosis of interstitial cystitis/painful bladder syndrome

Study Objective: Chronic pelvic pain is often a manifestation of interstitial cystitis (IC), for which several symptom scoring measures exist. However, the receiver operating characteristic (ROC) curves for these scores have not been described, even though such analysis could identify an optimal noninvasive test and suggest diagnostic test thresholds. The objective of this study was to develop ROC curves for IC symptom scores based on the standard of pain relief after cystoscopy with hydrodistention (HD). Design: This is a retrospective analysis of IC symptom index (ICSI) and visual analog scale (VAS) bladder pain (VASb) scores recorded at initial patient visit. Patients underwent a diagnostic algorithm leading to selected HD. The ROC curves were calculated based on the presence of diagnostic criteria for IC found at HD (Canadian Task Force classification III). Setting: A multidisciplinary chronic pelvic pain referral center. Patients: A total of 277 women with chronic pelvic pain were evaluated. The mean duration of pain was 54 months; mean pelvic pain VAS score was 7.5. Those proved to have IC had a VASb score of 7 and an ICSI score of 11. Interventions: Initial symptom score tabulation followed by a symptom-based diagnostic algorithm consisting of alkalinized lidocaine instillation with HD offered to responders. Measurements and Main Results: The ROC curve for the VASb was shifted to the upper left compared with the ICSI, which was closer to the diagonal. Area under the curve was significantly greater for VASb (0.860) than ICSI (0.773) (p =.045). The maximum diagnostic accuracy for the ICSI was at a value of 14 or more (0.88) and for the VASb at a value of 7 or more (0.94). Conclusion: The most accurate symptom score for detecting IC based on this analysis was the VASb with a threshold of 7. Although the ICSI may have use, in this setting it is not as useful as the VAS for identifying patients who eventually prove to have IC.