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RAND Interstitial Cystitis Community Epidemiology Study (RICE) Validated Through Comparison Study With IC/BPS Diagnosed Community Cohort
The RICE survey, the most comprehensive population-based study of IC/BPS done in the United States, estimated that between 2.7% and 6.5% of American women have bladder symptoms consistent with a diagnosis of IC/BPS. Specificity varied from 54% to 83% as sensitivity of the population assay diminished with more specific diagnostic criteria.
Katy S. Konle and co-authors from the University of Michigan and the Rand Corporation examined the demographic and clinical characteristics of the large community based RICE cohort, and compared them with those of a smaller, clinically managed, expert-physician diagnosed IC/BPS cohort typical of study populations traditionally used in clinical and basic research studies. Was the RICE population, from which inferences of an extremely high prevalence of the disorder have been drawn, similar enough in terms of demography and clinical characteristics to a defined IC/BPS patient population to confer face-validity to the prevalence data obtained? The important answer appears to be yes.
While RICE patients were considerably more likely to be uninsured (to be expected given the differences in how the 2 cohorts were recruited), both groups had an average symptom duration of 14 years. Baseline pain and maximum pain were slightly worse in the clinical cohort, but the Interstitial Cystitis Problem Index was significantly higher in the RICE cohort indicating that the symptoms identified in the telephone survey were not incidental and not clinically irrelevant. Naturally, the clinical cohort group had undergone far more IC/BPS diagnostic tests and received many more condition-specific treatments. About a quarter of both groups had been diagnosed and treated for overactive bladder. The authors went on to compare the high sensitivity and high specificity RICE cohorts and found only small differences.
This is an important addition to the urologic literature and worth reviewing in detail in the publication. My only thought is that the groups are not totally comparable, as we would expect that the rate of misdiagnosis in the clinical cohort (given how we define the syndrome) would be extremely low, and the rate of false attribution of the symptoms to IC/BPS in the RICE cohort is about 33%, given the calculated specificity assumptions. Nevertheless, it appears we have a large reservoir of undiagnosed, unrecognized IC/BPS. Should we develop truly effective therapies in the future, it would behoove us to find these patients.
Konkle KS, Berry SH, Elliott MN, Hilton L, Suttorp MJ, Clauw DJ, Clemens JQ.
Reference: J Urol. 2012 Feb;187(2):508-12.
doi: 10.1016/j.juro.2011.10.040
PubMed Abstract
PMID: 22177158
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