Asthma is a condition that affects the airways - the small tubes that carry air in and out of the lungs. When a person with asthma comes into contact with something that irritates their airways (an asthma trigger), the muscles around the walls of the airways tighten so that the airways become narrower and the lining of the airways becomes inflamed and starts to swell. Sometimes, sticky mucus or phlegm builds up, which can further narrow the airways.
Asthma affects an estimated 300 million people worldwide and 30 million people in Europe. For most people, asthma is a life-long condition, especially if it starts in adulthood. But for some children diagnosed with asthma, the condition might improve or disappear completely as they get older. It can return later in life, though, sometimes triggered by events such as menopause or lifestyle or environment changes, such as going to a new workplace that means you’re exposed to more of your triggers.
These reactions cause the airways to become narrower and irritated - making it difficult to breath and leading to symptoms of asthma, such as chest tightness, wheezing, or coughing. Asthma is one of the top five chronic diseases globally, along with heart disease, stroke, cancer and diabetes.
World Health Organisation
Severe asthma, although difficult to define, is becoming an increasing problem to manage for patients and for healthcare systems. There are various definitions of this chronic condition, but a widely accepted definition of severe asthma established by a taskforce, supported by the European Respiratory Society (ERS) and American Thoracic Society (ATS) has defined severe asthma as ‘‘asthma which requires treatment with high dose inhaled corticosteroids (ICS) plus a second controller (and/or systemic corticosteroids) to prevent it from becoming ‘uncontrolled’ or which remains ‘uncontrolled’ despite this therapy.’’
Uncovering Asthma Report