Prevalence of interstitial cystitis in young women

Traditional epidemiologic studies have significantly underestimated interstitial cystitis (IC) prevalence because they surveyed populations for diagnosed cases rather than screening for IC symptoms and evaluating suspected cases. Our earlier data have suggested that IC affects almost 25% of women. To test this hypothesis, we used a validated IC symptom questionnaire and intravesical potassium sensitivity testing (PST), history, and physical examination to determine the prevalence of IC in a fixed population of young women.

All female members of the University of California, San Diego, third-year medical student class were asked to complete the Pelvic Pain and Urgency/Frequency (PUF) scale. All those scoring 7 or greater were asked to undergo clinical evaluation, including urinalysis, urine culture, and PST.

Of 52 potential subjects, 49 (median age 26 years) completed the PUF scale. Of the 49, 15 (30.6%) scored 7 or greater; 5 of those 15 volunteered for PST. All 5 had negative urinalysis findings and were PST positive, for a 10% (5 of 52) rate of positive voluntary PST in the medical student population. All 15 subjects with PUF scores of 7 or greater reported being sexually active. Dyspareunia was present in 13 (87%) of the 15 women, including all 5 PST-positive subjects.

We identified probable IC in 30.6% and documented IC in a minimum of 10% of the female medical students. These data suggest the estimate of IC prevalence in the United States should be vastly increased from approximately 1.5 million to perhaps 25 to 30 million women and that IC is highly prevalent in young women. Screening for IC-specific symptoms is a useful method for identifying undiagnosed IC cases.