About 10% of adults have suffered an attack of asthma, and up to 5% of these have severe disease that responds poorly to treatment. Patients with severe disease have an increased risk of death, but patients with mild-to-moderate disease are also at risk of exacerbations. Most guidelines about the management of asthma follow stepwise protocols. This review does not endorse or follow any particular protocol, but presents the evidence about specific interventions.
Methods and outcomes
We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of treatments for chronic asthma? What are the effects of treatments for acute asthma? We searched: Medline, Embase, The Cochrane Library, and other important databases up to June 2008 (Clinical Evidence reviews are updated periodically; please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA).
We found 99 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions.
In this systematic review we present information relating to the effectiveness and safety of the following interventions. For acute asthma: beta2 agonists (plus ipratropium bromide, pressured metered-dose inhalers, short-acting continuous nebulised, short-acting intermittent nebulised, and short-acting intravenous); corticosteroids (inhaled); corticosteroids (single oral, combined inhaled, and short courses); education about acute asthma; generalist care; helium-oxygen mixture (heliox); magnesium sulphate (intravenous and adding isotonic nebulised magnesium to inhaled beta2 agonists); mechanical ventilation; oxygen supplementation (controlled 28% oxygen and controlled 100% oxygen); and specialist care. For chronic asthma: beta2 agonists (adding long-acting inhaled beta2 agonists when asthma is poorly controlled by inhaled corticosteroids, or short-acting inhaled beta2 agonists as needed for symptom relief); inhaled corticosteroids (low dose and increasing dose); leukotriene antagonists (with or without inhaled corticosteroids); and theophylline (when poorly controlled by inhaled corticosteroids).
About 10% of adults have suffered an attack of asthma, and up to 5% of these have severe disease that responds poorly to treatment. These people have an increased risk of death.
Most guidelines about the management of asthma follow stepwise protocols. This review does not endorse or follow any particular protocol, but presents the evidence about specific interventions.
Taking short-acting beta2 agonists as needed is as likely to relieve symptoms and improve lung function as a regular dosing schedule in adults with chronic asthma.
Adding long-acting beta2 agonists to inhaled corticosteroids decreases the number of exacerbations and improves symptoms, lung function, and quality of life in people with mild-to-moderate persistent asthma that is poorly controlled with corticosteroids.
CAUTION: Long-acting beta2 agonists have been associated with increased asthma-related mortality, and should always be used with inhaled corticosteroids.
Low-dose inhaled corticosteroids improve symptoms and lung function in persistent asthma compared with placebo or regular inhaled beta2 agonists.
Leukotriene antagonists are more effective than placebo at reducing symptoms, but we don't know if adding leukotriene antagonists to inhaled corticosteroids is of benefit in people with chronic asthma.CAUTION: Leukotriene antagonists have been associated with a possible increased risk of neuropsychiatric events.Adding theophylline to inhaled corticosteroids may improve lung function in people with mild or moderate chronic asthma that is poorly controlled with inhaled corticosteroids, but we don't know if they are of benefit compared with long-acting beta2 agonists or leukotriene antagonists.
In people with an acute attack of asthma, supplementation of beta2 agonists with 28% oxygen, systemic corticosteroids (short courses), additional beta2 agonists (various routes of administration), or ipratropium bromide improve symptoms.
Inhaled corticosteroids seem to improve lung function in people with acute asthma. However, we don't know whether inhaled corticosteroids are as effective as systemic corticosteroids at improving symptom severity, lung function, and hospital admissions.
Inhaled plus oral corticosteroids and oral corticosteroids alone may have similar effects in preventing relapse and improving lung function.Beta2 agonists delivered from a metered-dose inhaler using a spacer are as effective at improving lung function as those given by a nebuliser or given intravenously. Giving beta2 agonists intravenously is more invasive than giving beta2 agonists by nebuliser.In people with severe acute asthma, continuous nebulised short-acting beta2 agonists may also improve lung function more than intermittent nebulised short-acting beta2 agonists.We don't know if intravenous magnesium sulphate,
nebulised magnesium alone, or adding nebulised magnesium to inhaled beta2 agonists improves lung function in people with acute asthma.We don't know whether helium-oxygen mixture (heliox) is more effective at improving lung function compared with usual care.
Mechanical ventilation may be life saving in severe acute asthma, but it is associated with high levels of morbidity.
Specialist care of acute asthma may lead to improved outcomes compared with generalist care.We don't know whether education to help self-manage asthma improves symptom severity, lung function, or quality of life, but it may reduce hospital admissions.