Chronic Bronchitis and Chronic Obstructive Pulmonary Disease

Abstract

Chronic bronchitis (CB) is a common but variable phenomenon in chronic obstructive pulmonary disease (COPD). It has numerous clinical consequences, including an accelerated decline in lung function, greater risk of the development of airflow obstruction in smokers, a predisposition to lower respiratory tract infection, higher exacerbation frequency, and worse overall mortality. CB is caused by overproduction and hypersecretion of mucus by goblet cells, which leads to worsening airflow obstruction by luminal obstruction of small airways, epithelial remodeling, and alteration of airway surface tension predisposing to collapse. Despite its clinical sequelae, little is known about the pathophysiology of CB and goblet cell hyperplasia in COPD, and treatment options are limited. In addition, it is becoming increasingly apparent that in the classic COPD spectrum, with emphysema on one end and CB on the other, most patients lie somewhere in the middle. It is known now that many patients with severe emphysema can develop CB, and small airway pathology has been linked to worse clinical outcomes, such as increased mortality and lesser improvement in lung function after lung volume reduction surgery. However, in recent years, a greater understanding of the importance of CB as a phenotype to identify patients with a beneficial response to therapy has been described. Herein we review the epidemiology of CB, the evidence behind its clinical consequences, the current understanding of the pathophysiology of goblet cell hyperplasia in COPD, and current therapies for CB.Keywords: chronic obstructive pulmonary disease; chronic bronchitis; goblet cell hyperplasia; N-acetylcysteine; roflumilast Chronic obstructive pulmonary disease (COPD) is a common disease characterized by irreversible airflow obstruction and persistent inflammation to noxious environmental stimuli, usually cigarette smoke. It affects 12 to 16 million people in the United States and is the third leading cause of death and disease burden worldwide (1). COPD encompasses a spectrum of diseases, with chronic bronchitis (CB) at one end and emphysema at the other, with most individuals having some characteristics of both. The CB definition used in epidemiologic studies has been variable, but the classic definition is chronic cough and sputum production for at least 3 months per year for two consecutive years (2). CB has numerous clinical consequences, including an increased exacerbation rate, accelerated decline in lung function, worse health-related quality of life (HRQoL), and possibly increased mortality (3-6). We review the clinical phenotype of CB, the current understanding of its pathophysiology, and treatment options. EPIDEMIOLOGYCB is common in the general population. Table 1 provides an overview of the prevalence of cough and sputum production in population-based studies. CB is seen in 3.4 to 22.0% of adults (7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19). This wide range of prevalence estimates may be due to varying definitions of CB (i.e., chronic phlegm ver...

Chronic bronchitis is associated with severe exacerbation and prolonged recovery period in Chinese patients with COPD: a multicenter cross-sectional study

“…Additionally, although we did not find statistical relationship between recovery period and FEV1 %pred, we found that recovery period was prolonged as severity of airflow limitation increased. Third, Mucous metaplasia and mucus overproduction are the pathologic foundation of CB (23). Therefore, we speculated that exacerbation type in patients with CB were more likely to belong to Anthonisen I/II, which was significantly associated with late recovery (17).…”

The cost-effectiveness of domiciliary non-invasive ventilation in patients with end-stage chronic obstructive pulmonary disease: a systematic review and economic evaluation

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Persistent and Newly Developed Chronic Bronchitis Are Associated with Worse Outcomes in Chronic Obstructive Pulmonary Disease

“…Chronic bronchitis affects up to 22% of nonsmokers and 14-74% of patients with chronic obstructive pulmonary disease (COPD) (2). Chronic bronchitis has been associated with worse outcomes in COPD, including a greater exacerbation frequency, more respiratory hospitalizations, worse health-related quality of life, greater lung function decline, and possibly increased mortality (3)(4)(5)(6)(7).…”