Chronic rhinosinusitis (CRS) is prevalent among U.S. patients with bronchiectasis, and is associated with several other conditions, including asthma, allergic rhinitis, gastroesophageal reflux disease (GERD), and antibody deficiency, a study has found.
The study, “Prevalence and Characterization of Chronic Rhinosinusitis in Patients with Non–Cystic Fibrosis Bronchiectasis at a Tertiary Care Center in the United States,” was published in the International Forum of Allergy & Rhinology.
Bronchiectasis is typically divided into two categories: cystic fibrosis (CF)-associated and non-CF-associated, depending on whether it is linked to CF, a genetic disease that affects the lungs. Only non-CF-associated bronchiectasis was investigated in this report.
Although the precise sequence of events that leads to bronchiectasis is not fully understood, it is thought that a “vicious cycle” of inflammation, airway damage, impaired mucus clearance, and frequent respiratory infections play a role in the onset and development of the disease. Airway inflammation in bronchiectasis is normally driven by neutrophils, a type of white blood cell that normally helps to resolve infections and the healing of damaged tissues.
A previous study conducted outside the U.S. found that up to 62% of adults with bronchiectasis also have CRS — a disease in which nasal passages (sinuses) become inflamed — and that this was associated with a poorer quality of life, and a higher degree of disease severity.
Unlike airway inflammation in bronchiectasis, which is normally driven by neutrophils, CRS is typically associated with eosinophils. Neutrophils and eosinophils are two different types of white blood cells that are part of the body’s defense mechanisms against microbes.
However, according to researchers, this possible link between bronchiectasis and CRS, coupled with the high numbers of eosinophils seen in some patients, could challenge the role of neutrophils in bronchiectasis.
But this association between bronchiectasis and CRS has never been confirmed in the U.S., and on top of that, the exact link between these two conditions is still speculation at this point.
To better understand the possible association between non-CF-associated bronchiectasis and CRS in U.S. patients, researchers retrospectively analyzed the medical records of 900 adult patients seen at Northwestern University Feinberg School of Medicine in Chicago between 2007 and 2017.
Results showed that CRS was detected in 45% (408 out of 900) of patients with bronchiectasis, which is lower than the 62% reported outside the U.S.
“One possible explanation for the lower prevalence of CRS specifically in U.S. patients with bronchiectasis would be differences in environmental exposures. This lower prevalence may also be attributable to regional differences in the primary etiology [origin],” the researchers wrote.
After controlling for demographic factors, asthma, allergic rhinitis, GERD, and antibody deficiency were all found to be associated with the presence of CRS in patients with bronchiectasis.
“This finding is clinically relevant as past evidence suggests that CRS and other comorbidities contribute to increased exacerbation frequency and decreased quality of life in patients with bronchiectasis,” the researchers wrote.
In addition, they found that peripheral eosinophil counts were significantly higher in patients with bronchiectasis and CRS (251.5) than in patients with bronchiectasis alone (165.9).
This finding raises the question of whether the increased number of eosinophils is caused by chronic rhinosinusitis (a traditionally eosinophilic disorder), or if a different disease mechanism may be at play in this subgroup of patients.
In this regard, a hypothesis called the “united airways” states that diseases of the upper (e.g., CRS) and lower (e.g., bronchiectasis) respiratory tract “may be secondary to a similar pathogenic mechanism,” the researchers wrote.
According to the team, if this hypothesis is correct, the use of biologic agents targeting inflammation linked to high levels of eosinophils should be studied in patients with both disorders.
Based on the results, the researchers suggested that “patients with bronchiectasis should be evaluated for CRS, especially if they have comorbid asthma, allergic rhinitis, GERD, or antibody deficiency.”
Those with bronchiectasis and CRS should also “be promptly diagnosed and treated by a multidisciplinary team of allergists, otolaryngologists, and pulmonologists to minimize the likely increased burden associated with their concomitant disease,” they added.
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