People with smaller airways than others are more likely to develop chronic obstructive pulmonary disease (COPD) one day, even if they have never smoked.
- In France, 1.7 million people suffer from chronic obstructive pulmonary disease (COPD).
- According to a new study, people with narrow airways are more at risk.
- This phenomenon, dysanapsis, would be an even greater risk factor than smoking.
Chronic obstructive pulmonary disease (COPD) is a lung infection characterized by a persistent decrease in inspired gas flow. The patient sees his airways obstructed and his lungs drown more each day in thick mucus. The main symptoms are shortness of breath, coughing and frequent spitting up. According to WHO, these signs gradually worsen with shortness of breath on exertion, even at rest. Disease “tends to be underdiagnosed and can be life-threatening”, alerts the Organization. In France, 1.7 million people are affected. If most often, it is due to tobacco, 25 to 30% of patients are non-smokers. According to a new study published in the JAMAthese people would have narrower airways than others.
To reach this conclusion, the researchers examined the imaging results of more than 6,500 adults with or without COPD, smokers or not, observed in three studies. After taking into account factors such as smoking, exposure to smoke, air pollution or occupational exposures, they then discovered that an anomaly was much more common in patients: dysanapsis.
During growth, in some people, for some unknown reason, the airways do not grow as much as expected, whereas the development of the airways is supposed to be proportional to that of the lungs. The patients concerned therefore had bronchi that were too narrow in relation to the size of their lung, which restricted their breathing capacity.
Better breathing capacity for heavy smokers who don’t get sick?
“These results show that a smaller airway relative to the size of the lungs is a very important risk factor for COPD.”, commented in a press release Dr. Benjamin Smith, of McGill University (Canada), lead author of the study. These data confirm a previous study which showed that 50% of COPD in the elderly was due to poor lung function rather than its accelerated decline.
In heavy smokers who had never developed COPD, the researchers observed a significant basic respiratory capacity: their bronchi were wide in relation to their lung capacity. Also, this sizeable respiratory reserve could give them a “physiological reserve” capable of supporting the narrowing of the airways caused by smoking, the researchers suggest. “It is possible that someone with this type of lungs can tolerate the bad effects of cigarettes, but it is very important to (…) quit smoking, even if you have lungs with a lot of reserves”insists Dr. Smith.
On the contrary, people who have never smoked but who have small airways “may not need an additional risk factor” to develop COPD. “It has been found that in people with smaller airways, the risk of COPD is much higher, even in non-smokers. When we did a comparison with other risk factors, including cigarettes, it seems that dysanapsis is even more important.” develops Benjamin Smith.
“If the airways are too small, it is more difficult to breathe”
“It’s very mechanicalillustrates Dr. Smith. It is exactly like a sink or a bathtub. If the pipe is too small, there may be problems with the drainage of the system. It is exactly the same with the lungs: if the airways are too small, it is more difficult to breathe.”
In fact, there would therefore be two main reasons for COPD in the elderly: either low lung function at the start of life, which would therefore represent 50% of the risk of developing the pathology in adulthood, or an accelerated decline in lung function due to long-term harmful exposures such as cigarette smoke.
However, to confirm the “logical” suggestion establishing dysanapsis as a risk factor for COPD, further research is needed. If this were confirmed, treatments could then be developed to improve the situation for those affected, the researchers hope.
More and more people with COPD in the world
According to a study published in November in The European Respiratory Journal, the number of patients diagnosed with COPD continues to increase throughout the world. According to the WHO, 175 million people were affected by this disease in 2015. On the other hand, the mortality rate due to this disease decreased by 12% between 2000 and 2015.
“The data suggests that the proportion of COPD patients who die prematurely due to the disease is decreasing overall, which is very encouraging. This means that people may be less exposed to risk factors now that the disease is managed more effectively,” therefore analyzed the authors of the study. Nevertheless“although the death rate from COPD may decline over time, this decline is too small to compensate for the fact that more and more people are dying of COPD each year due to aging populations.”
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