An article published this week in the new edition of Current Opinions in Pulmonary Medicine provides an essential overview of the current clinical picture for Chronic Bronchitis (CB).  Study Investigators conducted a thoroughly researched literature review that focused on the environmental risk factors, epidemiology and genetic components of the disease.  The aims of the paper, entitled “The chronic bronchitis phenotype in chronic obstructive pulmonary disease: features and implications,” were to elucidate the mechanisms that cause CB using current research, and in doing so, establish better clinical methods of patient evaluation and treatment.

CB is one of two diseases known to cause chronic obstructive pulmonary disease (COPD); emphysema is the other.  There is currently not an agreed upon clinical definition used in the medical community to diagnose CB,  but broadly it is defined  as a productive cough for three months in each of two successive years, for which there is no other clinical cause. CB is a major public health concern and ranks third in overall worldwide mortality.  It affects 10 million people worldwide.  Adults between the ages of 18-44 make up 31.2% of those diagnosed. The main risk factor for CB is being a current smoker, but ongoing research is shedding light on possible environmental causes such as exposure to air pollutants, dusts, fumes, and burning of bio mass fuels.

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It is this ongoing research that the study authors reviewed to make conclusions on the potential attributing factors to the disease and their role in the clinical setting.  The literature on risk factors provided data with environmental, epidemiological, and genetic importance, including:

• Ozone studies have shown diminished lung function, reduced exercise capacity, and lung inflammation at levels at or below the National Ambient Air Quality Standards of air quality. Increased ozone levels were associated with greater emergency department visits for CB.

• The burning of Bio mass fuels consisting of wood, dung, and crop residues predominantly affects women in rural areas who use the fuel for cooking and contributes to their higher rate of diagnosis.

• Air pollution increases rates of COPD and CB by increasing the body’s inflammatory response.

• On computer tomography (CT) scan CB is associated with greater airway wall thickening and gas trapping within the lungs.

• The reasons why a certain population of smokers are not susceptible to CB due to their genetic make-up is not fully understood.

The medical community agrees that CB has an acceleratory effect on lung function decline, it significantly worsens a patient’s quality of life, and attributes globally to high rates of mortality; what isn’t agreed upon is the precise definition to diagnose CB, and this is a problem, as it contributes to a high rate of undiagnosed and untreated patients. For clinicians, having thorough answers to the pathophysiology of the disease will result in the development of better therapies that will be more successful in improving patients’ lung function while also decreasing mortality rates.  This study adds to the growing body of literature that aims to provide those needed answers.