This entry addresses two chronic respiratory diseases, asthma and chronic obstructive pulmonary diseases (COPD) with a combined global prevalence of 2% of the general population (Hosseini et al., 2019). COPD is a generic label of diseases that includes chronic bronchitis and emphysema. Asthma and COPD are inflammatory diseases of the lung. Although the inflammatory mechanisms differ, in both cases inflammation creates airways restriction that causes symptoms, breathlessness, wheeze and cough. Asthma is defined as airways restriction that is reversible by bronchodilator drugs. COPD is defined as non-reversible airways restriction. However, reversibility varies in degree and there is some overlap between the two diseases. Both diseases vary in severity from mild to very severe. Psychosocial factors relevant to mild disease are different from those relevant to severe disease. In severe disease there can be frequent inpatient hospital visits due to exacerbations (i.e., sudden reduction in lung function and increase in symptoms) that require specialist stabilisation. Exacerbations – also known as asthma attacks – are less common in mild and moderate disease which are often treated entirely in primary care. Severe disease is usually treated in secondary or tertiary specialist clinics
Asthma and COPD have some differences that are relevant to a psychosocial understanding of these diseases. Asthma develops early (typically between the ages two to six years) or late (typically after forty years). COPD develops late (after about forty years of age) and is almost exclusively related to exposure to dirty air (air particulates) in particular smoking. Most COPD patients are aware of the relationship between prior lifestyle and disease. Asthma is a chronic disease where understanding of cause is less certain and where severity remains relatively constant over the long term. Asthma can be fatal but in most cases is well controlled by drugs. COPD is a progressive and terminal disease of gradually worsening lung function, though symptoms can be reduced by medication and lifestyle. Although long term outlook is poor, there is substantial variation in rate of lung decline between COPD patients.