PURPOSE: Interstitial cystitis is a chronic and debilitating syndrome but surprisingly little is known about its epidemiology. This study was designed to estimate the prevalence of interstitial cystitis among women in the United States. MATERIALS AND METHODS: Female participants in the Nurses' Health Study (NHS) I and II (184,583) were asked by mailed questionnaires whether they had ever been diagnosed with interstitial cystitis. We requested and reviewed medical records of women self-reporting interstitial cystitis. The accuracy of self-reports was evaluated using standardized criteria. RESULTS: Among the 93,428 women who responded to the NHS II questionnaire and 91,155 women who responded to the NHS I questionnaire 1,354 (1.4%) and 357 (0.4%), respectively, self-reported interstitial cystitis. Based on medical record review 63 cases of interstitial cystitis were confirmed in NHS II and 47 in NHS I. The prevalence of interstitial cystitis was 67/100,000 women in NHS II and 52/100,000 in NHS I. There was no substantial variation in prevalence by age. CONCLUSIONS: The prevalence of interstitial cystitis in the United States is more than 50% greater than previously reported and 3-fold greater than that reported in Europe.
PURPOSE:Interstitial cystitis is a chronic and debilitating syndrome but surprisingly little is known about its epidemiology. This study was designed to estimate the prevalence of interstitial cystitis among women in the United States. MATERIALS AND METHODS: Female participants in the Nurses' Health Study (NHS) I and II (184,583) were asked by mailed questionnaires whether they had ever been diagnosed with interstitial cystitis. We requested and reviewed medical records of women self-reporting interstitial cystitis. The accuracy of self-reports was evaluated using standardized criteria. RESULTS: Among the 93,428 women who responded to the NHS II questionnaire and 91,155 women who responded to the NHS I questionnaire 1,354 (1.4%) and 357 (0.4%), respectively, self-reported interstitial cystitis. Based on medical record review 63 cases of interstitial cystitis were confirmed in NHS II and 47 in NHS I. The prevalence of interstitial cystitis was 67/100,000 women in NHS II and 52/100,000 in NHS I. There was no substantial variation in prevalence by age. CONCLUSIONS: The prevalence of interstitial cystitis in the United States is more than 50% greater than previously reported and 3-fold greater than that reported in Europe.