For many patients with asthma, the concern that this “reversible” though serious, potentially life-threatening persistent lung disease may progress into emphysema, is real and worrisome. After all, asthma along with emphysema and chronic bronchitis, the latter two conditions known as Chronic Obstructive Pulmonary Diseases (COPD), all have inflammation with airway narrowing, mucus production and airway obstruction. Symptoms are also similar; patients may present with wheezing, shortness of breath, chest tightness and cough.

Furthermore, there is concern that studies examining the prevalence (how common the disease is), morbidity (complications of the disease affecting one’s quality of life), and costs have shown that asthma and emphysema bear some resemblance to one another. For example, in the United States, nearly 5-10% or 15-30 million Americans have asthma or emphysema, with exacerbations accounting for significant loss of time each year from work (and school, for children with asthma). This amounts to $24 billion dollars each year for asthma medications (medications are a major cost for asthma), and a staggering $480 billion dollars for hospitalizations of patients with chronic bronchitis and emphysema. Several years ago, the increase in cases and morbidity of asthma and emphysema prompted the National Heart, Lung and Blood Institute (NHLBI) of the National Institutes of Health (NIH) in conjunction with the World Health Organization (WHO) to develop a Global Initiative for Asthma (GINA) and Initiative for Chronic Obstructive Lung Disease (GOLD) for physicians to recognize, diagnose and treat all forms of asthma and emphysema.

In fact, studies examining the basic immunology, diagnosis and treatment of asthma suggest that asthma and emphysema are distinct and different diseases. It is well accepted that the major triggers for asthma attacks include allergies and viral infections, whereas the major cause of emphysema is cigarette smoking. Only 1% of deaths associated with respiratory diseases is due to asthma, and occur when patients lack medication, or are unable to receive emergency medical care. Contrast this to the greater than 50% of deaths associated with chronic bronchitis and emphysema. Short and long acting bronchodilators, steroids and combination bronchodilator/steroid preparations are available to treat asthma. Many studies have also concluded that allergy shots (immunotherapy) effectively treat and prevent exacerbations of asthma due to allergies in children and adults when patients are appropriately selected and managed. The drugs needed to treat asthma may reduce symptoms in patients with emphysema, but do not influence longevity.

Similarly, research studies designed to study the mechanisms of asthma have helped us understand the basic differences between asthma and emphysema. Until recently, the classic teaching has been that asthma, unlike emphysema and chronic bronchitis, is a reversible disease, and that steroids and bronchodilators reduce the inflammation, open the airways, control symptoms, and prevent permanent changes from occurring in the lungs. Newer research shows that this teaching is not entirely correct. Current studies suggest that patients with all forms of chronic persistent asthma-mild, moderate or severe-may undergo cellular and structural airway changes referred to as “remodeling” that occurs in conjunction with, or because of, chronic airway inflammation. These structural changes may lead to thickening of the airway wall, airflow limitation, fixed, irreversible obstruction, and abnormal lung function studies. The changes seen in asthma are similar to some characteristics of emphysema, however, unlike emphysema, destruction and fibrosis (scarring) of the airway walls are not seen in asthma. This means that airway remodeling may predispose patients with asthma to have persistent daytime and/or nighttime asthmatic symptoms, and undergo non-destructive changes in the airways that are caused by inflammation. One study in adults with asthma suggested a possible mechanism of remodeling to be the loss of lung elastic recoil, which means the lung airways have lost the flexible “rubber band” quality needed for normal breath taking. Chest computerized tomography (CT) scans of the lungs in these patients were normal, suggesting again the absence of emphysema in all patients with persistent asthma. This condition has been called “pseudo physiologic emphysema”; that is, asthma which resembles emphysema due to the loss of elastic recoil, but lacks the permanent damage or scarring typically seen in emphysematous lungs.

Thus, patients with persistent asthma are at risk for losing lung elastic recoil, but not for developing emphysema, as may occur with years of smoking. To avoid asthmatic complications and ensure good health, patients should have regular medical visits with their health care provider in the management of their asthmatic condition, and keep allergies under good control with proper education, immunotherapy and medications.
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