Prevalence of Crohn’s disease is similar between the United States and several European countries, but the majority of Americans with the illness are unaware of their status, according to a recent study.
Researchers evaluated data from 7,798 patients who participated in the National Health and Nutrition Examination Survey between 2009 and 2010. Participants were interviewed regarding prior Crohn’s disease (CD) diagnoses and dietary habits, and serum samples were analyzed for IgA tissue transglutaminase antibodies (tTGA) plus endomysial antibodies (EMA) if initial results were abnormal.
Patients tested positive for tTGA in 49 cases, including 15 who were weakly positive. Of the tTGA-positive participants, 30 subsequently tested positive for EMA, including two with weakly positive results. Five additional patients had a prior clinical CD diagnosis reported during interviews, resulting in 35 patients with CD across the entire cohort. Twenty-nine of these participants were previously unaware of their CD status.
Investigators calculated the prevalence for the illness as 0.71% (95% CI, 0.58-0.86%) throughout the United States, (equivalent to more than 1.8 million cases nationwide) and 1.01% (95% CI, 0.78-1.31%) among non-Hispanic whites specifically. The weighted prevalence of serologically diagnosed CD was 0.64% (95% CI, 0.51-0.81%) nationwide, or approximately 1.6 million cases, and 0.94% (95% CI, 0.71-1.23%) among non-Hispanic whites.
Gluten-free diets were practiced by 55 participants, with an estimated nationwide prevalence of 0.63% (95% CI, 0.36-1.07%), or 1.6 million people. The vast majority of patients on gluten-free diets tested negative for tTGA (53 patients), and six participants on the diet reported a CD diagnosis.
“By studying a nationally representative sample, we were able to estimate the prevalence of CD [defined by sequential serologic testing and reported clinical diagnosis of CD] in the U.S. population,” the researchers wrote, adding that the condition is not as rare in the United States as previously believed. “Our results confirm prior data showing that a substantial burden of CD in the United States predominantly affects the non-Hispanic white population.”