Signs and symptoms
Asthma is characterized by recurrent episodes ofAssociated conditions
A number of other health conditions occur more frequently in people with asthma, including gastroesophageal reflux disease (GERD), rhinosinusitis, and obstructive sleep apnea. Psychological disorders are also more common, with anxiety disorders occurring in between 16 and 52% and mood disorders in 14–41%. It is not known whether asthma causes psychological problems or psychological problems lead to asthma. Current asthma, but not former asthma, is associated with increased all-cause mortality, heart disease mortality, and chronic lower respiratory tract disease mortality. Asthma, particularly severe asthma, is strongly associated with development of chronic obstructive pulmonary disease (COPD). Those with asthma, especially if it is poorly controlled, are at increased risk for radiocontrast reactions. Cavities occur more often in people with asthma. This may be related to the effect of beta 2 agonists decreasing saliva. These medications may also increase the risk of dental erosions.Causes
Asthma is caused by a combination of complex and incompletely understood environmental and genetic interactions. These influence both its severity and its responsiveness to treatment. It is believed that the recent increased rates of asthma are due to changing epigenetics ( heritable factors other than those related to the DNA sequence) and a changing living environment. Asthma that starts before the age of 12 years old is more likely due to genetic influence, while onset after age 12 is more likely due to environmental influence.Environmental
Many environmental factors have been associated with asthma's development and exacerbation, including, allergens, air pollution, and other environmental chemicals. Smoking during pregnancy and after delivery is associated with a greater risk of asthma-like symptoms. Low air quality from environmental factors such as traffic pollution or highHygiene hypothesis
TheGenetic
Family history is a risk factor for asthma, with many different genes being implicated. If one identical twin is affected, the probability of the other having the disease is approximately 25%. By the end of 2005, 25 genes had been associated with asthma in six or more separate populations, including GSTM1, IL10, CTLA-4, SPINK5,Medical conditions
A triad of atopic eczema,Exacerbation
Some individuals will have stable asthma for weeks or months and then suddenly develop an episode of acute asthma. Different individuals react to various factors in different ways. Most individuals can develop severe exacerbation from a number of triggering agents. Home factors that can lead to exacerbation of asthma include dust, animal dander (especially cat and dog hair), cockroachPathophysiology
Asthma is the result of chronic inflammation of the conducting zone of the airways (most especially the bronchi and bronchioles), which subsequently results in increased contractability of the surrounding smooth muscles. This among other factors leads to bouts of narrowing of the airway and the classic symptoms of wheezing. The narrowing is typically reversible with or without treatment. Occasionally the airways themselves change. Typical changes in the airways include an increase in eosinophils and thickening of the lamina reticularis. Chronically the airways' smooth muscle may increase in size along with an increase in the numbers of mucous glands. Other cell types involved include T lymphocytes, macrophages, and neutrophils. There may also be involvement of other components of theDiagnosis
While asthma is a well-recognized condition, there is not one universal agreed upon definition. It is defined by the Global Initiative for Asthma as "a chronic inflammatory disorder of the airways in which many cells and cellular elements play a role. The chronic inflammation is associated with airway hyper-responsiveness that leads to recurrent episodes of wheezing, breathlessness, chest tightness and coughing particularly at night or in the early morning. These episodes are usually associated with widespread but variable airflow obstruction within the lung that is often reversible either spontaneously or with treatment". There is currently no precise test for the diagnosis, which is typically based on the pattern of symptoms and response to therapy over time. Asthma may be suspected if there is a history of recurrent wheezing, coughing or difficulty breathing and these symptoms occur or worsen due to exercise, viral infections, allergens or air pollution. Spirometry is then used to confirm the diagnosis. In children under the age of six the diagnosis is more difficult as they are too young for spirometry.Spirometry
Spirometry is recommended to aid in diagnosis and management. It is the single best test for asthma. If theOthers
TheClassification
Asthma is clinically classified according to the frequency of symptoms, forced expiratory volume in one second ( FEV1), and peak expiratory flow rate. Asthma may also be classified as atopic (extrinsic) or non-atopic (intrinsic), based on whether symptoms are precipitated by allergens (atopic) or not (non-atopic). While asthma is classified based on severity, at the moment there is no clear method for classifying different subgroups of asthma beyond this system. Finding ways to identify subgroups that respond well to different types of treatments is a current critical goal of asthma research. Although asthma is a chronic obstructive condition, it is not considered as a part ofAsthma exacerbation
An acute asthma exacerbation is commonly referred to as an ''asthma attack''. The classic symptoms areExercise-induced
Exercise can trigger bronchoconstriction both in people with or without asthma. It occurs in most people with asthma and up to 20% of people without asthma. Exercise-induced bronchoconstriction is common in professional athletes. The highest rates are among cyclists (up to 45%), swimmers, and cross-country skiers. While it may occur with any weather conditions, it is more common when it is dry and cold. Inhaled beta2-agonists do not appear to improve athletic performance among those without asthma, however, oral doses may improve endurance and strength.Occupational
Asthma as a result of (or worsened by) workplace exposures is a commonly reportedAspirin-induced asthma
Aspirin-exacerbated respiratory disease (AERD), also known as aspirin-induced asthma, affects up to 9% of asthmatics. AERD consists of asthma, nasal polyps, sinus disease, and respiratory reactions to aspirin and other NSAID medications (such as ibuprofen and naproxen). People often also develop loss of smell and most experience respiratory reactions to alcohol.Alcohol-induced asthma
Alcohol may worsen asthmatic symptoms in up to a third of people. This may be even more common in some ethnic groups such as the Japanese and those with aspirin-induced asthma. Other studies have found improvement in asthmatic symptoms from alcohol.Non-atopic asthma
Non-atopic asthma, also known as intrinsic or non-allergic, makes up between 10 and 33% of cases. There is negative skin test to common inhalant allergens. Often it starts later in life, and women are more commonly affected than men. Usual treatments may not work as well. The concept that "non-atopic" is synonymous with "non-allergic" is called into question by epidemiological data that the prevalence of asthma is closely related to the serum IgE level standardized for age and sex (P<0.0001), indicating that asthma is almost always associated with some sort of IgE-related reaction and therefore has an allergic basis, although not all the allergic stimuli that cause asthma appear to have been included in the battery of aeroallergens studied (the "missing antigen(s)" hypothesis). For example, an updated systematic review and meta-analysis of population-attributable risk (PAR) of ''Chlamydia pneumoniae'' biomarkers in chronic asthma found that the PAR for ''C. pneumoniae''-specific IgE was 47%.Infectious asthma
When queried, asthma patients may report that their first asthma symptoms began after an acute lower respiratory tract illness. This type of history has been labelled the "infectious asthma" (IA) syndrome, or as "asthma associated with infection" (AAWI) to distinguish infection-associated asthma initiation from the well known association of respiratory infections with asthma exacerbations. Reported prevalences of IA for adults range from around 40% in a primary care practice to 70% in a specialty practice treating mainly severe asthma patients. The true population prevalence of IA in adult-onset asthma is unknown because clinicians are not trained to elicit this type of history routinely, and recollection in child-onset asthma is challenging.Differential diagnosis
Many other conditions can cause symptoms similar to those of asthma. In children, symptoms may be due to other upper airway diseases such asPrevention
The evidence for the effectiveness of measures to prevent the development of asthma is weak. TheManagement
While there is no cure for asthma, symptoms can typically be improved. The most effective treatment for asthma is identifying triggers, such as cigarette smoke, pets, or aspirin, and eliminating exposure to them. If trigger avoidance is insufficient, the use of medication is recommended. Pharmaceutical drugs are selected based on, among other things, the severity of illness and the frequency of symptoms. Specific medications for asthma are broadly classified into fast-acting and long-acting categories. The medications listed below have demonstrated efficacy in improving asthma symptoms, however "real world" use-effectiveness is limited as around half of people with asthma worldwide remain sub-optimally controlled, even when treated. People with asthma may remain sub-optimally controlled either because optimum doses of asthma medications do not work (called "refractory" asthma) or because individuals are either unable (e.g. inability to afford treatment, poor inhaler technique) or unwilling (e.g., wish to avoid side effects of corticosteroids) to take optimum doses of prescribed asthma medications (called "difficult to treat" asthma). In practice, it is not possible to distinguish "refractory" from "difficult to treat" categories for patients who have never taken optimum doses of asthma medications. A related issue is that the asthma efficacy trials upon which the pharmacological treatment guidelines are based have systematically excluded the majority of people with asthma. For example, asthma efficacy treatment trials always exclude otherwise eligible people who smoke, and smoking blunts the efficacy of inhaled corticosteroids, the mainstay of asthma control management. Bronchodilators are recommended for short-term relief of symptoms. In those with occasional attacks, no other medication is needed. If mild persistent disease is present (more than two attacks a week), low-dose inhaled corticosteroids or alternatively, a leukotriene antagonist or aLifestyle modification
Avoidance of triggers is a key component of improving control and preventing attacks. The most common triggers includeMedications
Medications used to treat asthma are divided into two general classes: quick-relief medications used to treat acute symptoms; and long-term control medications used to prevent further exacerbation. Antibiotics are generally not needed for sudden worsening of symptoms or for treating asthma at any time.Medications of asthma exacerbations
* Short-acting beta2-adrenoceptor agonists (SABA), such as salbutamol (''albuterol'' USAN) are the first line treatment for asthma symptoms. They are recommended before exercise in those with exercise induced symptoms. * Anticholinergic medications, such as ipratropium, provide additional benefit when used in combination with SABA in those with moderate or severe symptoms and may prevent hospitalizations. Anticholinergic bronchodilators can also be used if a person cannot tolerate a SABA. If a child requires admission to hospital additional ipratropium does not appear to help over a SABA. For children over 2 years old with acute asthma symptoms, inhaled anticholinergic medications taken alone is safe but is not as effective as inhaled SABA or SABA combined with inhaled anticholinergic medication. Adults who receive combined inhaled medications that includes short-acting anticholinergics and SABA may be at risk for increased adverse effects such as experiencing a tremor, agitation, and heart beat palpitations compared to people who are treated with SABA by itself. *Older, less selective adrenergic agonists, such as inhaled epinephrine, have similar efficacy to SABAs. They are however not recommended due to concerns regarding excessive cardiac stimulation. *Corticosteroids can also help with the acute phase of an exacerbation because of their antiinflamatory properties. The benefit of systemic and oral corticosteroids is well established. Inhaled or nebulized corticosteroids can also be used. For adults and children who are in the hospital due to acute asthma, systemic (IV) corticosteroids improve symptoms. A short course of corticosteroids after an acute asthma exacerbation may help prevent relapses and reduce hospitalizations. *Other remedies, less established, are intravenous or nebulized magnesium sulfate and helium mixed with oxygen. Aminophylline could be used with caution as well. *Mechanical ventilation is the last resort in case of severe hypoxemia. * Intravenous administration of the drugLong–term control
* Corticosteroids are generally considered the most effective treatment available for long-term control. Inhaled forms are usually used except in the case of severe persistent disease, in which oral corticosteroids may be needed. Dosage depends on the severity of symptoms. High dosage and long term use might lead to the appearance of common adverse effects which are growth delay, adrenal suppression, and osteoporosis. Continuous (daily) use of an inhaled corticosteroid, rather than its intermitted use, seems to provide better results in controlling asthma exacerbations. Commonly used corticosteroids are budesonide, fluticasone, mometasone and ciclesonide. * Long-acting beta-adrenoceptor agonists (LABA) such as salmeterol and formoterol can improve asthma control, at least in adults, when given in combination with inhaled corticosteroids. In children this benefit is uncertain. When used without steroids they increase the risk of severe side-effects, and with corticosteroids they may slightly increase the risk. Evidence suggests that for children who have persistent asthma, a treatment regime that includes LABA added to inhaled corticosteroids may improve lung function but does not reduce the amount of serious exacerbations. Children who require LABA as part of their asthma treatment may need to go to the hospital more frequently. * Leukotriene receptor antagonists (anti-leukotriene agents such as montelukast and zafirlukast) may be used in addition to inhaled corticosteroids, typically also in conjunction with a LABA. For adults or adolescents who have persistent asthma that is not controlled very well, the addition of anti-leukotriene agents along with daily inhaled corticosteriods improves lung function and reduces the risk of moderate and severe asthma exacerbations. Anti-leukotriene agents may be effective alone for adolescents and adults, however there is no clear research suggesting which people with asthma would benefit from anti-leukotriene receptor alone. In those under five years of age, anti-leukotriene agents were the preferred add-on therapy after inhaled corticosteroids. A 2013 Cochrane systematic review concluded that anti-leukotriene agents appear to be of little benefit when added to inhaled steroids for treating children. A similar class of drugs, 5-LOX inhibitors, may be used as an alternative in the chronic treatment of mild to moderate asthma among older children and adults. As of 2013 there is one medication in this family known as zileuton. *Delivery methods
Medications are typically provided as metered-dose inhalers (MDIs) in combination with an asthma spacer or as a dry powder inhaler. The spacer is a plastic cylinder that mixes the medication with air, making it easier to receive a full dose of the drug. A nebulizer may also be used. Nebulizers and spacers are equally effective in those with mild to moderate symptoms. However, insufficient evidence is available to determine whether a difference exists in those with severe disease. For delivering short-acting beta-agonists in acute asthma in children, spacers may have advantages compared to nebulisers, but children with life-threatening asthma have not been studied. There is no strong evidence for the use of intravenous LABA for adults or children who have acute asthma. There is insufficient evidence to directly compare the effectiveness of a metered-dose inhaler attached to a homemade spacer compared to commercially available spacer for treating children with asthma.Adverse effects
Long-term use of inhaled corticosteroids at conventional doses carries a minor risk of adverse effects. Risks includeOthers
Inflammation in the lungs can be estimated by the level of exhaled nitric oxide. The use of exhaled nitric oxide levels (FeNO) to guide asthma medication dosing may have small benefits for preventing asthma attacks but the potential benefits are not strong enough for this approach to be universally recommended as a method to guide asthma therapy in adults or children. When asthma is unresponsive to usual medications, other options are available for both emergency management and prevention of flareups. Additional options include: * HumidifiedAlternative medicine
Many people with asthma, like those with other chronic disorders, usePrognosis
The prognosis for asthma is generally good, especially for children with mild disease. Mortality has decreased over the last few decades due to better recognition and improvement in care. In 2010 the death rate was 170 per million for males and 90 per million for females. Rates vary between countries by 100 fold. Globally it causes moderate or severe disability in 19.4 million people as of 2004 (16 million of which are in low and middle income countries). Of asthma diagnosed during childhood, half of cases will no longer carry the diagnosis after a decade. Airway remodeling is observed, but it is unknown whether these represent harmful or beneficial changes. Early treatment with corticosteroids seems to prevent or ameliorates a decline in lung function. Asthma in children also has negative effects on quality of life of their parents.Epidemiology
In 2019, approximately 262 million people worldwide were affected by asthma and approximately 461,000 people died from the disease. Rates vary between countries with prevalences between 1 and 18%. It is more common in developed than developing countries. One thus sees lower rates in Asia, Eastern Europe and Africa. Within developed countries it is more common in those who are economically disadvantaged while in contrast in developing countries it is more common in the affluent. The reason for these differences is not well known. Low and middle income countries make up more than 80% of the mortality. While asthma is twice as common in boys as girls, severe asthma occurs at equal rates. In contrast adult women have a higher rate of asthma than men and it is more common in the young than the old. In 2010, children with asthma experienced over 900,000 emergency department visits, making it the most common reason for admission to the hospital following an emergency department visit in the US in 2011. Global rates of asthma have increased significantly between the 1960s and 2008 with it being recognized as a major public health problem since the 1970s. Rates of asthma have plateaued in the developed world since the mid-1990s with recent increases primarily in the developing world. Asthma affects approximately 7% of the population of the United States and 5% of people in the United Kingdom. Canada, Australia and New Zealand have rates of about 14–15%. The average death rate from 2011 to 2015 from asthma in the UK was about 50% higher than the average for the European Union and had increased by about 5% in that time. Children are more likely see a physician due to asthma symptoms after school starts in September. Population-based epidemiological studies describe temporal associations between acute respiratory illnesses, asthma, and development of severe asthma with irreversible airflow limitation (known as the asthma-chronic obstructive pulmonary disease "overlap" syndrome, or ACOS). Additional prospective population-based data indicate that ACOS seems to represent a form of severe asthma, characterised by more frequent hospitalisations, and to be the result of early-onset asthma that has progressed to fixed airflow obstruction.Economics
From 2000 to 2010, the average cost per asthma-related hospital stay in the United States for children remained relatively stable at about $3,600, whereas the average cost per asthma-related hospital stay for adults increased from $5,200 to $6,600. In 2010, Medicaid was the most frequent primary payer among children and adults aged 18–44 years in the United States; private insurance was the second most frequent payer. Among both children and adults in the lowest income communities in the United States there is a higher rate of hospital stays for asthma in 2010 than those in the highest income communities.History
Asthma was recognized in ancient Egypt and was treated by drinking an incense mixture known asNotes
References
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* {{Good article Chronic lower respiratory diseases Human diseases and disorders Respiratory therapy Wikipedia emergency medicine articles ready to translate Steroid-responsive inflammatory conditions Wikipedia medicine articles ready to translate (full)