Eosinophilic esophagitis (EoE), which was barely recognized 20 years ago, affects at least 150,000 people in the United States, with three-quarters being adults, report Evan Dellon et al. in the April issue of Clinical Gastroenterology and Hepatology.
EoE, also known as allergic esophagitis, is an allergic inflammatory disease characterized by increased numbers eosinophils in the esophagus. Symptoms include difficulty swallowing, food impaction, and heartburn.
EoE is a newly recognized disease that has been increasingly diagnosed over the past decade, in children and adults. It is rare, but is believed to be increasing in prevalence.
Although some aspects of the epidemiology of EoE are understood, it has been a challenge to quantify the prevalence of EoE in the US, due to the lack of a central medical record system, inconsistent application of EoE diagnostic definitions, and difficulties in conducting population-based research at tertiary care referral centers.
Evan Dellon et al. set out to investigate the prevalence of EoE in the US, using health insurance claim data from 2009 through 2011 and methods not previously possible in this field.
They found that despite its relatively recent description, EoE is frequently diagnosed in the US, with an estimated prevalence of 56.7/100,000 persons. The mean age of patients, surprisingly, was 33.5 years; 65% were male, 55.8% had dysphagia, and 52.8% had at least 1 other allergic condition. Prevalence peaked in men 35–39 years old (see figure).
Dellon et al. identified patients based on the International Classification of Diseases (ICD), 9th revision code for EoE (530.13). They state that this prevalence could be an underestimate, because knowledge of the code and recognition of EoE are increasing.
The authors observed that the prevalence of EoE decreases after age 45, which was unexpected, because other chronic and nonfatal diseases increase in prevalence with age. This observation could implicate early life exposure as an etiologic factor.
In an editorial that accompanies the article, Andrew J. Gawron says that future studies are needed to determine why middle-aged men appear to be more affected than other populations and why EoE is uncommon among certain ethnic groups. It will also be interesting to investigate whether there a possible birth cohort effect, due to undefined previous common exposures among patients, and what the reasons are for regional variations of EoE prevalence.
Gawron warns that it is important to recognize potential bias and to promote accurate use studies based on ICD-9 codes, to avoid false-alarms and pseudo-epidemics.