Risk factors for developing COPD if you have asthma?

Earlier I explained "How Asthma Becomes COPD." In this post, I would like to explain what the risk factors are for asthma becoming COPD. Here's what to know.

The link between asthma and COPD

A 2004 study showed a definite link between asthma and COPD. Researchers studied 3,000 people for 20 years. They concluded that asthmatics have a 12 times greater risk for developing COPD than non-asthmatics.^1-2

COPD is consistent with airflow obstructions that are only partially reversible. This results in persistent airflow limitation. This can make you feel some shortness of breath even on good COPD days. However, despite airway obstructions being irreversible, symptoms can be minimized with proper treatment.

Asthma also causes airflow obstructions. However, these are completely or almost completely reversible with time or treatment. This means that asthma can be controlled, meaning that symptoms can be prevented. This can be accomplished with proper treatment.

Asthma itself is considered a risk factor for COPD.¹ Not all asthmatics will be diagnosed with COPD. In fact, most will not. However, one study found that about 20% of asthmatics had persistent airflow limitation.¹ When this happens, asthma may be considered COPD.

Other than asthma itself, here are four risk factors for shifting asthma under the COPD umbrella.

1. Cigarette smoke. This would include both first and second-hand smoke. This is the leading risk factor for asthmatics developing COPD. About 39% of asthma-COPD cases are caused by cigarette smoke.¹
2. Hyper-responsive airways. These are asthmatics airways that are very sensitive (twitchy) to asthma triggers. This may happen with the development of airway remodeling and scarring. This is the second greatest risk factor for asthmatics developing COPD. About 15% of asthma-COPD cases are caused by hyper-responsive airways.¹
3. Poor lung growth in children with asthma.  This may be due to childhood asthma. Asthma in childhood may cause a person to experience a lung function deficit that may persist into adulthood. When this happens it may increase the likelihood of an eventual diagnosis of COPD.  Likewise, children with more severe asthma, and children with asthma and another similar condition (such as allergic rhinitis), were the most likely to have a decline in lung function.^{1, 4-5}
4. Severe asthma. Today, it is understood that 5-10% of asthmatics have severe asthma. This is asthma that continues to be poorly controlled despite adherence to an asthma treatment regimen. One study showed that 40% of children with severe asthma were diagnosed with COPD in adulthood. In comparison, only 8% of children with intermittent asthma, or children with no asthma, were diagnosed with COPD in adulthood. So, there appears to be a possible link between asthma severity and an eventual diagnosis of COPD. One probable reason that severe asthma may lead to COPD is damage to airways due to repeated asthma attacks. This may lead to airway remodeling that makes airways abnormally narrow, similar to COPD. This may cause persistent airflow limitation, resulting in a diagnosis of COPD.^5-7

Asthma is not emphysema or chronic bronchitis

Keep in mind that asthma is not emphysema in that it does not cause loss of lung tissue. Also, keep in mind that asthma is not chronic bronchitis. However, airway remodeling may result from the above risk factors. And this remodeling may make airways chronically narrow. It is this that may cause persistent airflow limitation that fits the definition of COPD. Only when this happens does asthma fit under the umbrella term COPD. Some experts may diagnose this as a duo diagnosis of asthma and COPD. Others may lump it under the term Asthma/ COPD Overlap Syndrome (ACOS).