Limitations of the Literature. The Panel proceeded with full awareness of the limitations of the IC/BPS literature. These limitations include: poorly-defined patient groups or heterogeneous groups; small sample sizes; lack of placebo controls for many studies, resulting in a likely over-estimation of efficacy; short follow-up durations; and, use of a variety of outcome measures. With regard to measures, even though the most consistently used measure was some form of patient-rated improvement scale, the scales differed across studies in anchor points, number of gradations, and descriptors. Overall, these difficulties resulted in limited utility for meta-analytic procedures. The single metaanalysis reported here was used to calculate an overall effect size for data from randomized trials that evaluated pentosan polysulfate (PPS). No comparative procedures were undertaken.