Bronchiectasis increases mortality risk in moderate-to-severe COPD
Bronchiectasis is independently associated with an increased mortality risk in patients with moderate-to-severe COPD, according to a new study from researchers in Spain.
Bronchiectasis, a permanent and progressive dilation of the lung’s airways, is common in COPD patients and is associated with longer and more intense exacerbations, more frequent bacterial colonization of the bronchial mucosa, and a greater degree of functional impairment.
“As COPD patients with bronchiectasis have an increased incidence of other known prognostic factors, we hypothesized that bronchiectasis itself would also have prognostic value,” said lead author Miguel Ángel Martínez-García, MD, of La Fe University and Polytechnic Hospital in Valencia, Spain. “We found that the presence and severity of bronchiectasis were associated with an increase in all-cause mortality in patients with moderate-to-severe COPD, independent of other known risk factors, including pulmonary function and other comorbidities.”
The findings were published online ahead of print publication in the American Thoracic Society’s American Journal of Respiratory and Critical Care Medicine.
The multicenter prospective observational study included 201 consecutive patients with moderate-to-severe COPD; 115 of them (57.2%) had bronchiectasis, which was diagnosed by high-resolution computed tomography (CT) scan of the chest. COPD severity was classified according to Global Initiative for Chronic Obstructive Lung Disease (GOLD) criteria.
During a median 48 months of follow-up, there were 51 deaths, including 43 among the patients with bronchiectasis. In a multivariate analysis adjusted for dyspnea, body mass index, presence of potentially pathogenic microorganisms in sputum,comorbidities, number of severe exacerbations and other potentially confounding factors, bronchiectasis was associated with a significantly increased risk of all-cause mortality (hazard ratio 2.54, 95%CI, 1.16-5.56; p=0.02).Age, Charlson Index, and post-bronchodilator ratio of forced expiratory volume in 1 second were also shown to have prognostic value.
Bronchiectasis is a term that describes damage to the walls of the large airways, or bronchial tubes, of the lung. Inflammation due to infection or other causes destroys the smooth muscles that allow the bronchial tubes to be elastic and prevents secretions that are normally made by lung tissue to be cleared.
Normal branching of the airways of the lung demonstrates a gentle taper that occurs at each branch point, like the branches of a tree. This tapering results in decreased resistance in the larger branches, enabling mucus or other objects to be funneled to the larger airways and eventually, with a cough, ejected out through the mouth. Loss of this normal anatomic tapering of the airways by damage due to inflammation causes the walls of the airways to be irregularly shaped. Secretions tend to pool in the distorted airways rather than be expelled, and these stagnant secretions are a breeding ground for bacterial growth. These bacteria, in turn, cause further irritation and inflammation, airway damage, and hence more secretions, initiating a “vicious cycle” of damage. This increases the risk of infections to spread directly into the airspaces of the lungs resulting in pneumonia.
Bronchiectasis is a form of chronic obstructive pulmonary disease (COPD) which also includes emphysema and chronic bronchitis. Bronchiectasis can be present alone, but usually more than one of the aforementioned components of COPD coexist in the same person.
The study had a few limitations, including that some variables that have been shown to predict mortality in COPD were not included in the analysis and exact measurement of the size of the bacterial load in sputum samples was not possible.
“If the prognostic value of bronchiectasis in patients with moderate-to-severe COPD that we found is confirmed in further and larger studies, it would have an important clinical impact,” said Dr. Martínez-García, “Bronchiectasis can be reliably diagnosed with high-resolution CT scanning, and effective treatments are available, potentially reducing the risk of mortality in patients with COPD.”
There are three classifications of bronchiectasis which describe the severity of the condition:
Cylindrical - most common and refers to the slight widening of the respiratory passages. This type can be reversed and may be seen after acute bronchitis
Varicose - bronchial walls have both extended and collapsed portions
Cystic - most severe and involves irreversible ballooning of the bronchi
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