Inflammatory basis of overlap syndrome explored
MedWire News: The inflammatory basis of overlap syndrome (OS) is similar to that of its constituent parts - chronic obstructive pulmonary disease (COPD) and obstructive sleep apnoea (OSAS), research shows.
The study of induced sputum from patients with each condition showed that their sputum shared the presence of a high percentage of neutrophils.
It is established that both COPD and OSAS are characterized by local and systemic inflammation. But the authors were unaware of any studies that have investigated the inflammatory characteristics in patients with both diseases.
They performed a Berlin Questionnaire to assess the presence of the principal OSAS symptoms, a pulmonary function test, and a nocturnal oximetry and polysomnography on 72 patients.
The participants included 18 patients with OS, 15 COPD patients, 16 OSAS patients, 12 obese individuals without OSAS or COPD, and a control group of 11 healthy individuals.
Sputum was induced from all patients and cell patterns within their sputum analyzed. The relationships between these cell patterns and the degree of obesity, airway obstruction, and OSAS severity were also evaluated.
Analysis showed that the average proportion of neutrophils in the induced sputum was higher in patients with OS (74.3%), COPD (63.3%), and OSAS (60.7%) than in the obese (43.5%) and normal weight (32.0%) control groups.
No significant difference in neutrophil levels in sputum were found among the patients with OS, COPD, and OSAS.
Donato Lacedonia (University of Foggia, Italy) and co-workers say that patients with OSAS, COPD, or OS share an increase in neutrophils in the airway, but add that they may be sustained by different mechanisms in the different diseases.
They conclude in the journal Respiratory Medicine: "OS is the only disease in which upper and lower airway obstruction are both present and often associated with obesity.
"It is for this reason that in this case each phenomena can likely contribute to sustained inflammatory status."
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By Cher Thornhill