Abstract
Sputum cell counts have identified inflammatory subtypes of bronchitis in relatively small numbers of subjects with asthma, chronic obstructive pulmonary disease (COPD) and chronic cough in research studies. The prevalence of different subtypes of bronchitis in routine clinical practice, however, has not been reported. To examine the heterogeneity of bronchitis and its relationship to the severity of airflow obstruction. A retrospective cross-sectional survey based on a computerized database of spontaneous or induced sputum cell counts examined in a large university tertiary respiratory outpatient clinic. The database contained 4232 consecutive sputum records from 2443 patients with chronic cough (39%), asthma (37%), asthma with COPD (9%), COPD (13%) and bronchiectasis (3%). Total and differential cell counts were obtained from 86% of successful sputum samples. Induced sputum provided more viable samples than spontaneous expectorate. Approximately one-third of patients with asthma and one-fifth of patients with COPD experience eosinophilic bronchitis. Asthmatic patients with moderate to severe airflow obstruction had a greater number of sputum eosinophils. There was a significantly higher number of total cell counts and percentage of neutrophils in the sputum of COPD patients with moderate and severe airflow obstruction than in those with mild airflow obstruction. There is heterogeneity in the cellularity of sputum in various airway diseases. Patients with clinically stable airway diseases may have high sputum cell counts. During exacerbations, more patients may experience neutrophilic bronchitis. Severity of airflow obstruction is associated with eosinophilic bronchitis in patients with asthma, and neutrophilic bronchitis in patients with nonasthmatic COPD.
Highlights
L D’silva, N Hassan, H-Y Wang, et al Heterogeneity of bronchitis in airway diseases in tertiary care clinical practice
Severity of airflow obstruction is associated with eosinophilic bronchitis in patients with asthma, and neutrophilic bronchitis in patients with nonasthmatic chronic obstructive pulmonary disease (COPD)
The objective of the present study was to describe our experience of using sputum cell counts in clinical practice within an academic outpatient clinic, and to demonstrate the variability of inflammatory subtypes in different airway diseases and its relation to severity of airflow obstruction
Summary
Sputum cell counts in relation to severity of airflow obstruction Spirometry data (postbronchodilator FEV1 and vital capacity) were available for 1074 patients with asthma and 265 patients with COPD. There was a significantly higher number of total cells and percentage of neutrophils in the sputum of COPD patients with moderate and severe chronic airflow obstruction than in those with mild airflow obstruction, whereas no significant difference was found in the percentage of eosinophils (Tables 4 and 5). The present study demonstrated that it is feasible to implement quantitative cell counts in sputum as a clinical test, which could be successfully achieved in the majority of patients and provide evidence that there is heterogeneity in the cellularity of sputum in various airway diseases. Patients may experience uncontrolled bronchitis even when symptoms are deemed
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