Chronic bronchitis could indicate COPD subtype

Chronic bronchitis is common among patients with chronic obstructive disease (COPD) and may represent a subtype of the disease that places patients at risk for increased severity and exacerbations, say researchers.

Jean Corhay (CHU Sart-Tilman, Liège, Belgium) and colleagues studied 974 patients with Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage 2–4 disease, and found that 64% had chronic bronchitis, defined as cough and sputum production for over 3 months of 2 consecutive years.

These patients had significantly more chronic respiratory failure, cachexia, and skeletal muscle wasting than other patients, as well as a greater number of pack–years smoking, poorer spirometry results, and were more likely to have emphysema. The researchers also note that the proportion of patients with chronic bronchitis increased with GOLD stage.

Patients with chronic bronchitis had nearly twice as many exacerbations per year as patients without, at 2.08 versus 1.05 episodes per patient, as well as significantly more severe exacerbations per year (0.3 vs 0.2).

Additionally, 37.3% of patients with chronic bronchitis had two or more moderate or severe exacerbations per year compared with 14.2% of patients without chronic bronchitis. And, these patients were more likely to be hospitalized, at 0.52 compared with 0.38 admissions per patient per year in those without chronic bronchitis.

In multivariate analysis, frequent exacerbation was the most important variable associated with chronic bronchitis, predicting a 3.3-fold greater odds for the concomitant condition. Other factors included current smoking (odds ratio [OR]=2.3), chronic respiratory failure (OR=1.9), and emphysema (OR=1.3).

Writing in the International Journal of Clinical Practice, Corhay and colleagues say that their results help clarify the prevalence of chronic bronchitis among COPD patients, as well as suggest that it “could represent a subtype of COPD that is easy to identify in clinical practice and appears to be associated with increased disease severity and with a high risk of exacerbations.”

However, writing in an accompanying editorial, Pierre-Regis Burgel (Paris Descartes University, France) disagrees.

“[A]ssessment of individual risk cannot rely on this single disease attribute,” he comments, noting that in a previous study the risk for COPD-related death was moderately increased in those with chronic bronchitis and mild airflow limitation but markedly increased in those with chronic bronchitis and severe airflow limitation.

“In conclusion, cough and sputum production may be markers of an active disease process in COPD patients, and may be used, in association with other [patient] characteristics, to identify patients at high risk of outcomes (e.g., exacerbations, death).”

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