Asthma Subgroups: Diagnosing, Treating Persistent Eosinophilic Asthma

In 1990, Jean Bousquet and company were the first to link high eosinophil levels with asthma severity.¹ In 1999, Sally Wenzel and company were the first to link severe asthma with eosinophilia.² In 2008, persistent eosinophilic asthma was identified as an asthma subgroup.³ Here is how it is diagnosed and treated.

Diagnosing persistent eosinophilic asthma

Considering it’s a relatively new asthma subgroup, and because it is rare, it may often go undiagnosed. This can result in poorly controlled asthma, hospitalizations, and generally poor quality of life.² This makes a diagnosis of eosinophilic asthma especially important. A diagnosis begins by recognizing severe asthma.

Severe asthma

This is usually diagnosed by the observation that you continue to have poorly controlled asthma despite the highest doses of inhaled corticosteroids and frequent boosts of systemic steroids. Pulmonary function tests may show diminished lung function.^2,4

Chronic sinusitis and nasal polyps

Once a diagnosis of severe asthma is made, a search should be ongoing to discover what subgroup of severe asthma you have. The observation that you have chronic sinus infections, along with nasal polyps, and possibly even otitis media, should point the finger at eosinophilic asthma.^2,4

Tissue and sputum eosinophilia

Persistent eosinophilic asthma is diagnosed when you have a persistently elevated (meaning for at least 5 years in a row) number of eosinophils (greater than 2% of inflammatory cells) in the tissues lining your respiratory passages, including your upper airways (nose and sinus passages) and lower airways (bronchioles). Since airway cells are in your sputum, the simplest way of determining tissue eosinophilia is by obtaining a sputum sample, which should show sputum eosinophilia.^2,4,6

Sputum sample

It is obtained by you spitting phlegm from deep inside your airways into a sterile cup. This can then be sent to a laboratory for analysis, where cells will be counted, and eosinophil level determined. While there are other means of diagnosing tissue eosinophilia, a sputum sample is the simplest and most reliable method at the present time.^4,5

Bronchoscopy

This is where a tube is inserted into your airway to obtain tissue samples (biopsy). These can then be sent to a lab where a tissue eosinophil level can be obtained.²

Childhood or early-onset

Persistent eosinophilic asthma can be diagnosed in childhood, although nasal polyps probably won’t be present yet. Since most childhood asthmatics have allergic asthma, eosinophilic asthma may overlap with allergic asthma. However, in one study, only 33% of childhood-onset asthmatics had sputum eosinophilia compared with 63% of adult-onset asthmatics.^2,4

Adult or late-onset

However, more often than not, a diagnosis of eosinophilic asthma is not made until after the age of 21 and is generally made between the ages of 25 and 35. For this reason, it is often referred to as adult-onset or late-onset eosinophilic asthma. About 5% of adult asthmatics have eosinophilic asthma, with an equal prevalence among males and females. Also, most cases of adult-onset asthma are nonallergic intrinsic.^2,4

Treating persistent eosinophilic asthma

There are therapies that are specifically targeted for this subgroup, which is what makes diagnosis so important. Studies show that normalizing sputum eosinophilia results in fewer asthma episodes and hospitalizations. Some medications used to treat eosinophilic asthma include.⁴

Bronchodilators

All asthmatics should have bronchodilators, or rescue medicine (such as albuterol) nearby at all times. Asthmatics should have rescue inhalers. Most people with severe asthma also benefit from albuterol nebulizer treatments.

Corticosteroids

Inhaled corticosteroids reduce inflammation resulting in better asthma control. Some cases do appear to be steroid-refractory, meaning they do not respond to inhaled steroids. However, some experts contend that it will respond to the highest doses of inhaled corticosteroids and occasional boosts of systemic corticosteroids.^2,4,6

Leukotriene antagonists

Eosinophils are known to recruit leukotrienes, which also cause inflammation of upper and lower airways. Medicines like Singulair (montelukast) also seem to help, especially when eosinophilic asthma is combined with AERD, which is known to have high leukotriene levels.⁶

Biologics

Mepolizumab (Nucala), Reslizumab (Cinqair), and Omalizumab (Xolair) are monoclonal antibodies (biologics) that may reduce eosinophil levels to improve asthma control.^2,4

Pipeline

There are many other medicines in the pipeline that may help lower eosinophil levels, some of which may be approved for use by the FDA in the near or distant future. Researchers continue to work overtime to find medicines to help people with eosinophilic asthma.⁴

Bronchial thermoplasty

This is an invasive procedure where bronchial smooth muscles are literally burned away by using thermal heat. Studies have shown that this improves asthma control in some, and may be an option for anyone with steroid-refractory severe asthma.^3,4

Sinusitis may also be treated with antibiotics. Nasal polyps may be removed, although frequently grow back sometimes in a short period of time.²

The future of persistent eosinophilic asthma

Researchers are working overtime to better understand, and find better treatment options, for eosinophilic asthma. This may some day lead to asthma guidelines tailored specifically for this subgroup, rather than relying on the traditional generic asthma guidelines, to obtain ideal control.