Eosinophilic esophagitis (EOE) is a chronic, immune-mediated disease affecting the esophagus, the muscular tube connecting the mouth to the stomach. Recognized since the early 1990s, EOE has become a significant cause of digestive illness worldwide, moving from a rare finding to a commonly encountered diagnosis in gastroenterology. The condition is characterized by inflammation and damage to the esophageal lining, which affects a person’s ability to eat and swallow normally.
Defining Eosinophilic Esophagitis
Eosinophilic esophagitis is fundamentally an allergic inflammatory disorder of the esophagus. This condition is defined by the presence of a specific type of white blood cell, called eosinophils, infiltrating the esophageal tissue. Normally, eosinophils are virtually absent from the esophagus, but their accumulation here indicates an immune response, often triggered by food or environmental allergens. The presence of 15 or more eosinophils per high-power field in an esophageal biopsy is the standard histological threshold for diagnosis, alongside clinical symptoms of esophageal dysfunction.
The concentrated presence of these immune cells leads to chronic inflammation, which can cause structural changes in the esophagus over time. This ongoing damage may result in narrowing, scarring, and the development of rings or strictures in the esophageal wall. Common symptoms vary by age but frequently include dysphagia, which is difficulty swallowing, and food impaction, where solid food gets physically stuck in the throat. In children, the disease may manifest as feeding difficulties, vomiting, or poor weight gain.
Global Prevalence and Incidence Rates
Quantifying the impact of EOE requires distinguishing between prevalence and incidence. Prevalence refers to the total number of existing cases at a specific time, while incidence measures the number of new cases diagnosed over a period. EOE is recognized as a global health issue, with the highest rates reported in high-income, industrialized countries, particularly in North America and Europe.
A recent systematic review estimated the global pooled prevalence of EOE to be around 40 cases per 100,000 inhabitants. The global pooled incidence rate, which accounts for new diagnoses, is estimated to be approximately 5.3 new cases per 100,000 people per year.
In the United States, prevalence estimates are often higher than the global average, with studies suggesting rates ranging from approximately 40 to over 160 cases per 100,000 population. A prevalence rate of 1 in 1000 people is an often-cited conservative estimate. These figures represent a significant increase from previous decades, suggesting that EOE is now a common cause of esophageal disease.
Demographic Patterns and Associated Conditions
EOE does not affect all populations equally, showing clear demographic patterns. The condition has a pronounced male predominance, with adult males having a risk of developing EOE that is about three to four times higher than that of females. This ratio is also observed in pediatric populations, though the disparity may be slightly less pronounced in children.
Diagnosis can occur at any age, but the highest prevalence is often reported in middle-aged adults, typically between 30 and 50 years old. While initially thought to be a childhood condition, EOE is now known to be common in adults as well, who often present with more advanced structural changes like esophageal narrowing due to long-standing inflammation.
A strong association exists between EOE and other allergic or atopic conditions. It is estimated that 50% to 80% of EOE patients also have a history of atopic diseases like asthma, eczema (atopic dermatitis), or allergic rhinitis (hay fever). This link highlights the immune-mediated and allergic nature of EOE, suggesting a shared underlying pathway with other common allergic disorders.
Understanding the Rise in Diagnosed Cases
The incidence and prevalence of EOE have risen dramatically since its initial recognition in the 1990s, a trend that has prompted significant research. This increase is thought to be due to a combination of two main factors: a true rise in disease frequency and improvements in diagnostic awareness. Early in the trend, increased recognition by physicians and the widespread adoption of upper endoscopy procedures likely accounted for many new diagnoses.
However, studies show that the rate of new EOE cases has outpaced the increase in diagnostic procedures, suggesting a genuine rise in the disease’s occurrence. This true increase is hypothesized to be linked to environmental shifts and modern lifestyle factors. The “hygiene hypothesis” proposes that reduced exposure to microbes in early childhood, due to cleaner environments, may lead to immune systems that are more prone to developing allergic responses.
Other factors implicated in the rise include changes in the modern diet, increased exposure to certain environmental allergens, and the widespread use of certain medications. For instance, the use of proton pump inhibitors (PPIs) and antibiotics early in life has been linked to a higher risk of EOE development in some studies. Furthermore, the decline in the prevalence of the bacterium Helicobacter pylori has also been temporally associated with the rise of EOE and other allergic disorders.