RAND Interstitial Cystitis Epidemiology Study

The RAND Interstitial Cystitis Epidemiology Study (RICE) is an observational study that sought to develop a case definition for Bladder Pain Syndrome (BPS)/Interstitial Cystitis (IC) with known sensitivity and specificity and to estimate the prevalence of the condition, which at the time had never been done using a large-population model. BPS/IC, which is clinically diagnosed based on patient-reported symptoms, is a poorly understood condition that can cause significant disability.

An expert panel developed a case definitions of BPS/IC based on a review of medical literature. This definition was tested on 599 adult women diagnosed with BPS/IC or other conditions characterized by pelvic symptoms. Testing revealed that no single epidemiological definition demonstrated both high sensitivity and high specificity, so two definitions were developed: one of high sensitivity/low specificity and one of low sensitivity/high specificity.
Using these two definitions, researchers then screened 96,995 US households to identify women who had bladder symptoms. Those with symptoms underwent a secondary, more intensive screening and were asked to provide more information regarding symptoms, medical history, medical treatments, impact on daily life, physical and mental health, and demographic information. Multivariate modeling was used to construct population and non-response weights. Weighted data was used to calculate prevalence estimates for both definitions and estimate the number of women affected.