Mild, persistent asthma is common but underdiagnosed and often undertreated. Regular controller treatment with lowdose inhaled glucocorticoids and rescue treatment with short-acting beta2-agonists as needed is recommended initially. Treatment is adjusted on the basis of the response within 3 to 4 months. The latest article in our Clinical Practice series comes from Dr. Elisabeth H. Bel of Academic Medical Center, Amsterdam. Asthma is a chronic inflammatory disease of the airways that is characterized by variable narrowing of the airways and symptoms of intermittent dyspnea, wheezing, and nighttime or early-morning coughing. Asthma is a major health problem throughout the world, affecting an estimated 315 million persons of all ages.
• What is the natural history of asthma in children and adults?
The development of asthma in children is influenced by genetic predisposition as well as by environmental factors, including viral infection and sensitization to aeroallergens (e.g., house dust mites or animal dander). Altered repair responses of the airway epithelium to these insults lead to inflamed airways, altered smooth-muscle function, and increased production of mucus. Persons who are born and raised on a farm have a reduced risk of allergy and asthma, probably because they have been exposed to a wide variety of microorganisms. Risk factors for the development of asthma in middle-aged and older adults are diverse and include work-related exposures (e.g., isocyanates or cleaning products) and lifestyle factors (e.g., smoking or obesity). The natural history of asthma varies considerably according to the age of the patient at first presentation, the severity of the asthma, and the patient’s sex. Mild asthma in children rarely progresses to severe disease, but severe and frequent wheezing is a well-established risk factor for persistence and severity of the disease in adulthood. Boys with asthma are more likely to “grow out” of their asthma, whereas asthma in girls is more likely to persist. Irreversible airflow limitation develops in some patients, particularly in those who have severe exacerbations.
• What is the role of trigger avoidance in asthma?
Relevant triggers that have been shown to aggravate asthma should be addressed and removed if possible. Exposure to aeroallergens has been convincingly shown to worsen asthma control in sensitized patients, but there is conflicting evidence about whether measures to reduce exposure to dust mites and furred pets, the most common indoor allergen sources, lead to better asthma outcomes. Randomized trials of single chemical or physical methods that are aimed at reducing dust-mite allergens, for example, have shown no significant effect on asthma symptoms. In addition, the clinical effectiveness of removing pets from the home remains unproven. Exposure to tobacco smoke increases the severity of asthma in children and adolescents, and active smoking reduces the response to asthma medication and causes long-term impairment of lung function. Smoke-free policies have been associated with a reduction in emergency hospitalizations for asthma. Gastroesophageal reflux is also common in patients with uncontrolled asthma; however, in a large, randomized, controlled trial, treatment with proton-pump inhibitors did not result in better asthma control.
Morning Report Questions
Q: What is the optimal medication for long-term control of asthma?
A: For the long-term control of asthma, inhaled glucocorticoids are the most potent and consistently effective medications for achieving overall treatment goals. These drugs are therefore the preferred therapy for patients with persistent asthma, including those who have generally well-controlled asthma but have had two or more asthma exacerbations requiring oral glucocorticoid therapy in the previous year. Constant low-dose inhaled glucocorticoid therapy has been shown in randomized, placebo-controlled trials to reduce asthma symptoms, improve asthma control and quality of life, improve lung function, diminish airway hyperresponsiveness, control airway inflammation, and reduce the frequency and severity of exacerbations. A large, nested, case-control study showed that persons who regularly used low-dose inhaled glucocorticoids had a reduced risk of death from asthma.
Q: What is the role of leukotriene inhibitors in the treatment of asthma?
A: Leukotriene modifiers are alternative medications for the long-term control of asthma. These drugs are particularly appropriate for patients who have concomitant allergic rhinitis or who have unacceptable local side effects with inhaled glucocorticoid therapy or an inadequate response to inhaled glucocorticoids. Large, randomized trials comparing leukotriene-modifier therapy with low-dose inhaled glucocorticoids in adults and children with mild, persistent asthma have shown that as compared with leukotriene-modifier therapy, inhaled glucocorticoid therapy results in significantly greater improvements with respect to most measures of asthma control. However, two large pragmatic trials performed in community settings showed that leukotriene-receptor antagonists were similar in efficacy to inhaled glucocorticoids as first-line controller therapy.