Abstract
Determining the overall US prevalence of Inflammatory Bowel Disease (IBD) is essential to national level prevention programs and population risk assessment; however currently US IBD prevalence remains uncertain. We used US National Health and Nutrition Examination Survey (NHANES) data to estimate the population-based prevalence of a self-reported history of medically diagnosed IBD, comparing to prior reports. Lifetime IBD prevalence for adults aged 20 + years was estimated in the independently conducted NHANES II (1976-80) and NHANES 2009-10 surveys. Participants were considered to have IBD if they reported being told by a physician they had Crohn's Disease (CD) or ulcerative colitis (UC). Clinically relevant NHANES data were analyzed to assess the self-reports. Survey design variables and sample weights were used to account for the complex survey design. The NHANES 2009-10 US IBD diagnosed prevalence was 1.2% (95% CI 0.8,1.6%), or an estimated 2.3 million persons. UC prevalence was 1.0% (95% CI 0.5,1.4%; 1.9 million persons) and CD prevalence was 0.3% (95% CI 0.1,0.4%; 578,000 persons). NHANES II UC prevalence was 1.0 (95% CI 0.8,1.2%), similar to 2009-10. UC prevalence was higher for ages ≥ 50 years in both surveys. NHANES 2009-10 data showed no UC sex differences, but women had higher UC prevalence in NHANES II. Remarkably, UC prevalence was similar between the two NHANES surveys fielded 30 years apart. The NHANES data are consistent with IBD prevalences reported in previous US nationally representative surveys, indicating that diagnosed IBD may affect approximately 1% of the US adult population.