Is eosinophilic asthma always severe?

[Blueforest23]

I was wondering about the following

1) Does anyone know what percent of asthma is eosinophilic

2) what percentage of eosinophilic asthma is severe?

I have looked at journal articles etc but couldn’t find an answer as different sites give totally different percentages

[Lysistrata Administrator Community Ambassador]

Hi,

I think it's easy to get the impression that eosinophilic asthma is more severe for two reasons:

1) Most of the available biologic treatments for severe asthma have been for eosinophilic asthma. These often gets reported as 'a new treatment for patients with especially severe asthma', without making it clear that it's for a certain kind of severe asthma.

2) Most people have tended not to get assessed for the type of asthma they have until it is severe and they're being referred to a severe asthma clinic and considered for biologics. Earlier in the process there's much less focus on what type of asthma someone has as the treatments used tend to be similar. That may not be the right approach necessarily but it is what's been happening, so someone with milder eosinophilic asthma may not know.they have raised eosinophils necessarily.

Off the top of my head - and I agree the estimates vary quite a bit - I think it's about 50-60% of asthmatics are eosinophilic, but that figure is probably a bit skewed by the fact that as I said, a lot of people are tested when they're more severe. It's often quite difficult to estimate properly how many people have a subtype of a disease and how that relates to severity - especially if the less common or well understood subtype (in this case non-eosinophilic) isn't always recognised as being part of the disease, or contributing to severe disease. Also people can have different types of asthma at the same time - this is made more complicated by the fact that 'non-eosinophilic' is actually several types.

Raised eosinophils*do* contribute to exacerbations and are associated with more frequent exacerbations in both COPD and asthma, but several studies have found they are not necessarily the top predictor of an attack - that seems to be most commonly a history of previous attacks,. especially in the last year, and patient-reported symptoms on the Asthma Control Questionnaire. And again - mostly people's eosinophils are measured when they're having attacks/are poorly controlled. Off the top of my head, I don't know how many studies there have been, if any, on eosinophil levels in mild asthmatics.

As someone with mostly non-eosinophilic asthma who has had admissions with zero eosinophils, I get annoyed when eosinophilic asthma is made out to be 'omg the worst'. It's more complicated than that - and there are usually more options currently for eosinophilic asthma which is severe, and scientifically we seem to understand this type better.