Asthma and asthma-like disorders

Bronchial asthma is defined as a chronic inflammatory disease resulting in a reversible and variable bronchial obstruction. For the clinical diagnosis of the disease there are some key indicators but as there is no 'gold standard' a correct diagnosis will sometimes not be obtained. Examples are patients in a symptom-free stage, current medication interfering with the methods used, patients with asthma-like symptoms reporting lack of effect of bronchodilators and patients who are unable to perform a forced expiration in an airway function test. The prevalence of asthma is reported to be 5-10%. The prevalence of asthma-like symptoms may be double this. The term 'asthma-like' has been used to an increasing extent during the last few years, which may indicate an increasing awareness of the fact that asthma-like symptoms are not always classical asthma. In this overview some disorders with asthma-like symptoms, especially in adults, are presented. The spectrum of differential diagnoses in a clinic may depend on which doctor/specialist the patient is consulting. In an asthma and allergy clinic it has been found that the most common differential diagnoses are chronic obstructive pulmonary disease (COPD), nonasthmatic cough and sensory hyper-reactivity (SHR), a disorder which is sometimes mixed up with asthma due to similar symptoms (heavy breathing, cough, increased secretion, difficulty in getting air etc.) and similar trigger factors (smoke, strong scents, exercise, cold air etc.). Recently it has been suggested that a capsaicin inhalation test may be an objective test for identifying patients with SHR. In asthma effective treatment is available today but in asthma-like disorders, such as SHR, no effective therapy is available, underlining the need of further research for understanding the pathophysiological mechanisms.