ASTHMA AND COPD

Hi just writing to see if any one has any information in relation to COPD and asthma and if the two do have a direct link. can you develop copd from asthma Thanks

spiderlungs

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Hi spiderlungs,

Tricky question - to an extent it's a question of sematics and how you define COPD.

COPD is an umbrella term for airway obstruction resulting from chronic bronchitis and emphysema, usually (but not always) as a result of cigarette smoking. The distinction between asthma and Chronic Obstructive Pulmonary Disease (COPD) is that asthma (usually) has a large element of reversibility and COPD (usually) doesn't - ie if you measure peak flow or FEV1, and then give a bronchodilator such as salbutamol, the numbers will improve significantly in asthma and less significantly in COPD.

However, there are exceptions to this rule. Some patients with asthma, especially those who have longstanding disease at the more severe end of the spectrum, get what's known as 'airway remodelling' - fixed hypertrophy (overgrowth) of the muscles surrounding the airways, producing a fixed narrowing of the airways. This will give them a low peak flow and FEV1 which does not respond to bronchodilators, and will be indistinguishable on testing from some types of COPD. You could call this COPD by definition, as it certainly is a chronic obstructive pulmonary disease (with little letters!) and indeed some respiratory physicians (including I believe the Asthma team at RBH) do describe this as COPD which has arisen from chronic severe asthma.

To further complicate things, some patients with a classical history for COPD do show quite marked reversibility - ie their peak flow and FEV1 improve significantly when given salbutamol. There is debate about whether these patients have true COPD (whatever that is) or not. The 'Dutch hypothesis' (bear with me, it gets better!) is that these folks have mild asthma, which progresses to COPD. The 'British hypothesis' is that these people have a distinct condition that is different from asthma and is caused by cigarette smoking, pollution etc.

Clearly it is a spectrum, with some people having pure asthma, some having pure bronchitis, some with pure emphysema, and many people who fit in somewhere in the middle, with elements of all of these conditions.

A complicated answer, I know, but the simpler version is that, yes, asthma can lead on to a COPD-like illness in some people.

Hope this helps rather than further confuses!

Em

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Oh gosh that was long.

Maybe I should have stuck to the simple answer!

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Hi spiderlungs and EmH, interesting thread.

So EmH, is it fair to say that most of the asthmatics on the AUK boards who have longstanding disease at the more severe end of the spectrum, will experience what's known as 'airway remodelling'. In other words they will go on to develop a form of COPD?

Is it also fair to say that chronic asthmatics who are not perhaps described as being at the severe end of the spectrum, will also experience a degree of 'airway remodelling'?

Derek

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EmH,

You say that the 'British hypothesis' is that these people have a distinct condition that is different from asthma and is caused by cigarette smoking, pollution etc. Hope I’m not being pedantic, but can you define “pollution, etc”. You see, it’s understandable that smoking can cause COPD, but I wouldn’t have thought pollution (per se) would cause COPD, unless we are talking about those who have been occupationally exposed to high levels of pollution (above occupational exposure limits).

Your further thoughts would be appreciated.

Derek

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Sorry Em, (as he trys to speak with wig between the teeth) – LOL

The 'Dutch hypothesis' is that these folks have mild asthma, which progresses to COPD. So how can someone with mild asthma develop COPD, or are you actually saying this could be someone with chronic mild asthma that has not been properly controlled over time.

Take hair,

Derek

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Oh goodness, Deek, I asked for that, didn't I?

Actually, it's strange, not all severe asthmatics do go on to develop airway remodelling, and some less severe asthmatics do get it. It's not really known what determines whether someone will get it or not, although genetic factors probably play a large part. It's thought that using antiinflammatory medication such as steroids has a large part to play in preventing or delaying the onset of airway remodelling.

Most authorities do acknowledge that air pollution probably plays a part in the development of COPD, although the effect is several orders of magnitude smaller than smoking. Certainly there is a large increase in mortality from COPD in times when there is heavy atmospheric pollution. While that doesn't necessarily implicate air pollution in the pathogenesis of COPD, there is a large body of evidence from patients who have COPD and don't have any other risk factors, that suggests that air pollution might have a role to play.

The 'Dutch hypothesis', as much as I can understand it (maybe you have to be Dutch?) is primarily suggesting that asthma and COPD are different manifestations of a single disease, with perhaps genetic or environmental factors determining what the exact clinical presentation is. Thus, someone with what would be thought of as mild asthma, may, by smoking, precipitate the development of the clinical condition of COPD.

This article explains it better than I could hope to:

findarticles.com/p/articles...

The great difficulty is that we don't know enough about the predisposing genetic factors in either condition to determine whether asthma and COPD do have a common aetiology. Clearly there is a lot of overlap, and reaching an exact diagnosis in any one person can be difficult. It's not helped by the fact that, although clear definitions of each condition do exist, asthma is defined in terms of airway physiology, while emphysema is a pathological diagnosis and bronchitis is diagnosed mainly on history. Unifying the conditions is therefore not easy!

Well hope I've answered a few of your questions and you're not chewing on that wig quite so frantically now!

Em

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Hello Spiderlungs, EmH and Derek,

Spiderlungs the jury seems to be out re the ‘link’ between asthma and COPD if you read the useful information posted by Derek and EmH.

Are you worried about this for yourself, or maybe on someone else’s behalf?

This is an interesting discussion though…

Having a rather personal interest in the aetiology of asthma/COPD (have diagnosed severe asthma/mild COPD) and just generally very curious by nature, I’m very interested in hearing/reading any evidence used to support the cause and subsequent development of this condition.

As well as a belief in genetic predisposing factors responsible for the development of either asthma or COPD, whether you smoke, have smoked in the past, or are a lifelong non smoker – I’m a lifelong non- smoker – I ‘ve come to the conclusion that air pollution must be far more of a contributory factor than medically acknowledged, although the latest evidence on the AUK home page, ‘Major roads linked to stunted lung growth’ concerning changes in lung function over time makes for provocative reading.

Its been well documented how changes in atmospheric pressure, for example just before a thunderstorm, can trigger breathing problems, regardless of the severity of diagnosed lung conditions, and, in some people, causing breathing difficulties for the first time.

On a personal anecdotal level I often wonder if the decade I spent training four times a week at very high levels of aerobic intensity in a sports stadium next to a notoriously ‘polluting’ factory, ( now closed down) and to include training during foggy cold nights, contributed to my worsening asthma. Ironically that also was my ‘golden’ decade of asthma control. Ho hum.

On a positive note exercise is beneficial for both lung and heart health. Even folks with severe COPD are encouraged into pulmonary rehabilitation.

But not in a cold foggy atmosphere.

Mia

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thanks a lot guys, mia yes its for my aunty whom has a long history with lung disease.

thank you all again

spider