Asthma (from the Greek άσθμα, ásthma, "panting") is the common chronic inflammatory disease of the airways characterized by variable and recurring symptoms, reversible airflow obstruction, and bronchospasm.[1] Symptoms include wheezing, coughing, chest tightness, and shortness of breath.[2] Asthma is clinically classified according to the frequency of symptoms, forced expiratory volume in 1 second (FEV1), and peak expiratory flow rate.[3] Asthma may also be classified as atopic (extrinsic) or non-atopic (intrinsic).[4]
It is thought to be caused by a combination of genetic and environmental factors.[5] Treatment of acute symptoms is usually with an inhaled short-acting beta-2 agonist (such as salbutamol).[6] Symptoms can be prevented by avoiding triggers, such as allergens[7] and irritants, and by inhaling corticosteroids.[8] Leukotriene antagonists are less effective than corticosteroids and thus less preferred.[9]
Its diagnosis is usually made based on the pattern of symptoms and/or response to therapy over time.[10] The prevalence of asthma has increased significantly since the 1970s. As of 2010, 300 million people were affected worldwide.[11] In 2009 asthma caused 250,000 deaths globally.[12] Despite this, with proper control of asthma with step down therapy, prognosis is generally good.[13]