Diagnosis of asthma

The diagnosis of asthma is confirmed if the patient demonstrates lower airway obstruction on lung function testing that is reversible spontaneously or by administering an inhaled bronchodilator. However, some patients might have cough as their only symptom and do not demonstrate airway obstruction. In these cases, bronchial challenge test with inhaled methacholine or histamine will result in significant airway obstruction in those patients with airway hypersensitivity. This test is of great value in diagnosing patients with asthma masquerading as chronic cough. Some patients only develop asthma symptoms with exercise, and would thus require an exercise challenge. Once asthma is diagnosed, it is important to ascertain the cause of the disease, as the prognosis and treatment are quite different. In children, the absence of allergy is a good prognostic factor, since most of these patients will outgrow their asthma. In adults, one must consider other types of asthma such as occupational asthma and aspirin-sensitive asthma. Allergy testing is therefore an important part of asthma evaluation, since the treatment of allergic asthma includes allergen avoidance and desensitization. Patients with occupational asthma usually need to have a career change, but might be eligible for compensation.

House dust mite allergen is the major cause of allergic asthma worldwide, and even more so in Hong Kong where the climate is warm and humid. It is therefore important to minimize soft furnishings such as carpets, cushions and upholstered furniture at home. The bed is a major reservoir of mite allergen, and should be encased with dust-impermeable covers. It is often necessary to evict animals from home if the patient is allergic to them. The mainstay of drug treatment for asthma is inhaled corticosteroid. These drugs can prevent airway inflammation, and are effective in reducing symptoms, exacerbations and rescue medication use. They have been shown to prevent airway remodeling, a process that leads to irreversible loss of lung function. Patients with allergic asthma should seriously consider undergoing allergen desensitization treatment. Desensitization has been shown to reduce steroid requirement over time, and children with rhinitis who received desensitization are less likely to develop asthma.

Reference information:  http://www.allergy.hk

The information aims to provide educational purpose only. Anyone reading it should consult physician before considering treatment and should not rely on the information above.