Eosinophilic oesophagitis (EoE)
What is eosinophilic oesophagitis?
Eosinophilic oesophagitis (pronounced e-o-SIN-o-FILL-ick e-sof-ah-JYE-tis) is often termed EoE for short. It is a medical condition affecting the oesophagus (food pipe through which swallowed food travels to the stomach). The condition is characterised by inflammation in the inner lining of the oesophagus, which is filled with a large numbers of eosinophils, a type of white blood cell. EoE can lead to troubling symptoms, and left unchecked over years can lead to a scarred, narrow oesophagus that cannot perform its functions effectively.
Who is at risk of developing eosinophilic oesophagitis (EoE)?
EoE can affect people in all age groups, but it is most commonly diagnosed in children, adolescents and young adults below the age of 40. Males are affected more commonly than females (approximately 3:1 ratio), and those of Caucasian ethnicity are at higher risk than other racial groups. The majority of patients diagnosed with EoE have a history of another allergic disorder (which may be mild or have resolved in childhood) – these include conditions such as asthma, eczema and rhinitis. A history of food allergies is also more common in patients diagnosed with eosinophilic oesophagitis. Sometimes, EoE is associated with a generalised eosinophilic disorder of the entire gastrointestinal tract; however in the majority of cases it is a disorder localised exclusively to the oesophagus.
How common is eosinophilic oesophagitis (EoE)?
EoE is a new disorder. The first few cases of patients which resembled EoE were observed in the 1960s and 1970s, and the disease was only formally recognised in 1993. Despite being a relatively new medical disorder, EoE is rapidly rising in incidence, and is no longer uncommon. The most recent estimate of its prevalence in Western countries is 63 cases per 100,000 population. This means that in Australia, there are over 15,000 people living with the condition. Based on the current trajectory, this number is expected to significantly increase over the coming years.
What is the cause of EoE?
The inflammation in the oesophagus that is seen in EoE is caused by an allergic reaction, most commonly towards certain food or foods that the person is ingesting. In people with EoE, the immune system inappropriately reacts to substances in the diet or the environment that are ordinarily harmless, and produces an inflammatory reaction in the oesophagus. This may occur because the person’s immune system is predisposed to produce an allergic reactions. In terms of why allergies are on the rise in Western countries, this is an area of ongoing intense medical research. However, a possible explanation may be the ‘hygiene hypothesis’.
Symptoms of eosinophilic oesophagitis
The symptoms of EoE vary by age group.
Difficulty eating/ swallowing
Dysphagia, or difficulty swallowing solid foods
Food impaction (piece of food stuck in the oesophagus)
FIRE (Food-induced Immediate Responsiveness of the oEsophagus): unpleasant sensation occurring immediately after contact of specific foods with the oesophagus
How is eosinophilic oesophagitis diagnosed?
While an experienced gastroenterologist can suspect the diagnosis in a typical patient, the diagnosis needs to be confirmed with an endoscopy and biopsy of the lining of the oesophagus. It is important that at least 6 biopsies are taken from the oesophagus, as fewer biopsies may miss the disease (which often affects the oesophagus in a patchy distribution). The biopsies are examined under a microscope and the condition can be diagnosed when there is inflammation with an excess of eosinophils (>15 per microscopic field of view).
Symptoms alone cannot be used to make the diagnosis (or assess response to treatment) as they can be variable and overlap with other conditions.
What is the role of allergy testing in eosinophilic oesophagitis (EoE)?
Being an allergic condition, one might assume that allergy testing would help identify the allergic triggers in patients with EoE. However, medical studies have shown that allergy testing (either via skin prick or atopy patch testing) is of limited value in the management of patients with eosinophilic oesophagitis, and the Australian National society of Allergy specialists recommends against routine allergy testing for patients with EoE. It seems that allergic reactions found during skin prick testing do not correlate with the allergic reaction going on in the oesophagus.
EoE food triggers
The six most common food groups that are the culprit in causing the allergy in EoE are:
Gluten-containing grains (wheat, barley, rye, spelt, oats, semolina)
Soy and legumes
It is important to note that patients with allergy to any of these foods may or may not experience symptoms immediately after consuming these foods. That is, just because a patient with EoE does not experience any symptoms after consuming one of these foods, does not mean it is not a trigger. Foods can lead to inflammation which only leads to symptoms a long time afterwards, rather than immediately upon consumption.
How is EoE treated?
There are two main components to the treatment strategy: (i) Inflammation needs to be brought under control, and (ii) any scar tissue (stricture) that has already developed needs to be dilated via endoscopy, as scar tissue is not responsive to anti-inflammatory therapy.
Proton pump inhibitors (PPIs)
This group of medications was initially developed to treat acid reflux, but has also been found to be effective in EoE where it reduces the allergic inflammation in the oesophagus. For this reason, PPIs are often a good choice of treatment for those patients who also suffer from acid reflux, since it can treat both conditions. PPIs are effective in approximately 50% of patients with EoE. If PPIs have not been effective, it can sometimes be due to the dose being too low; in most trials where they have been studied, high doses of PPI were used (typically twice daily dosing). PPIs are simple to take, safe to use and have minimal side effects.
Swallowed topical steroids
In a medical sense, topical refers to direct local application to the area of the body that is affected. Therefore, swallowed topical steroids are a useful treatment strategy in EoE as they are delivered directly to the oesophagus (by swallowing) and act locally by direct contact with the lining of the oesophagus. Further, there is negligible absorption of the medication into the rest of the body and bloodstream, meaning that side effects are minimal.
Swallowed topical steroids are effective in 70-90% of patients with EoE. If topical steroids have not been effective, it can sometimes be due to the dose being too low. Two forms of swallowed topical steroid are commonly used in Australia for EoE - recent medical studies have shown that both are equally effective, so either is acceptable to use. At present, these medications are not formulated specifically for use in eosinophilic oesophagitis, and we have to make do with the formulations used for asthma; but instead of inhaling the medicine, patients with EoE need to swallow it. Within the next couple of years, we should have access to topical steroids that are specifically formulated for EoE (these are now available in Europe), and will therefore be easier for patients to take. Until then, it is important that the patient’s gastroenterologist provides adequate written and visual explanation to the patient to ensure that they know how to take the medication correctly.
Since eosinophilic oesophagitis is in most cases an allergy to food(s) that the patient consumes, we can potentially treat the problem by removing those food(s) from the diet. Initial experience with dietary therapy involved an elemental diet in children. Elemental diet refers to a diet where the patient stops consuming all normal food and drink, and subsists completely on a liquid formula which contains all essential nutrients. While this was shown to be effective in treating the condition, it is not a palatable or long-term solution for patients.
Nowadays, a more practical and effective form of dietary therapy for eosinophilic oesophagitis are the empiric elimination diets (2-food, 4-food and 6-food elimination diets). These diets involve elimination and then sequential reintroduction of the 6 most common food triggers of EoE – animal milk, gluten-containing grains, egg, soy and legumes, nuts, and seafood. Through this process, the trigger food group(s) can be identified in approximately 70% of patients. This gives the patient the possibility of sustained remission from EoE without the need for long term medications. The main drawback of these elimination diets is the need for multiple endoscopies, as each time a food group is removed or reintroduced, an endoscopy with oesophageal biopsies is needed to check whether the disease is active or inactive.
Traditionally an elimination diet was performed with a ‘step down’ approach i.e. beginning with 6 food elimination and then reintroducing food groups if successful. More recently however, a step-up approach has become a viable alternative, i.e. starting with 2 food group elimination and working up to elimination of more food groups only if necessary. The choice between step-up and step-down approaches Is nuanced, individualised and is something to be discussed with your specialist. Any elimination diet must be undertaken under the guidance of a specialist gastroenterologist and dietitian.
Unlike the other therapies mentioned, dilatation has no effect on the level of inflammation in the oesophagus in EoE. Therefore, it is not appropriate as standalone treatment. However, conversely, none of the other therapies will have an effect on scar tissue that has already developed. Scar tissue in EoE takes the form of a narrowing of the oesophagus, or ‘stricture’. Strictures can be treated quite easily and effectively with dilatation of the oesophagus during routine endoscopy. It is important to treat strictures when present as, otherwise, the patient’s symptoms may not improve even if the inflammation is brought under control. In the past, some gastroenterologists were wary of dilating strictures but more recent medical studies have conclusively demonstrated that endoscopic dilatation of strictures in patients with eosinophilic oesophagitis is very safe.
How do I decide on the right treatment option for EoE?
All patients with eosinophilic oesophagitis should have some sort of therapy to control their inflammation, however there is no single ‘right treatment’ for all patients. Each of the 3 options (PPIs, swallowed topical steroids, and dietary therapy) are valid first-line treatment options. Each option needs to be discussed with the patient, and the choice of therapy should be tailored to their individual needs.
Is eosinophilic oesophagitis related to GORD (acid reflux)?
While there are some overlapping features, it is now recognised that eosinophilic oesophagitis and GORD are separate entities that may sometimes coexist in the same patient. While EoE is an allergic inflammatory disorder, GORD is a disorder where stomach acid inappropriately rises up into the oesophagus. Usually, they can be differentiated based on endoscopy and biopsies, but sometimes even based on those investigations they cannot be definitively differentiated. In these cases, use of PPI is usually recommended as first-line therapy since it treats both conditions.
Where can I find out more about EoE?
Get personalised information about your condition and treatment advice by making an appointment to see a specialist in eosinophilic oesophagitis. For further patient-focused support, AusEE is an Australian patient support group for individuals and families affected by eosinophilic oesophagitis.