Epidemiologic issues in interstitial cystitis.

As a result of variations in disease definition and diagnostic criteria for interstitial cystitis (IC), the performance of epidemiologic studies has been challenging. Initial prevalence studies used physician-confirmed diagnoses of IC; more recent studies, which have incorporated the use of patient responses to validated symptom questionnaires, indicate that the true prevalence of IC is much greater than the early studies suggested. Over the last decade, the recognized prevalence of IC has increased, and it is consistently greater among women compared with men. The most recent estimates indicate that at > or = 197 of every 100,000 women and > or = 41 of every 100,000 men in the United States are affected by IC. Because IC is substantially underdiagnosed, its actual prevalence may be much higher. Indeed, the disease may affect as many as 1 in 4 to 5 women and 1 in 20 men.