Updates to the Australian Asthma Handbook

Asthma is a chronic lung disease affecting one in nine Australians. The condition is characterised by hypersensitivity and inflammation of the airways which results in symptoms such as cough, wheeze, chest tightness, and breathlessness. While many people with asthma lead fit and healthy lives, the condition was responsible for 421 deaths and 39,448 hospitalisations in Australia in 2015. This highlights the need for optimisation of management strategies.

The National Asthma Council Australia (NACA) recently published an updated version of the Australian Asthma Handbook. The handbook is designed to provide healthcare professionals with best-practice, evidence-based advice for the management of asthma. The following revisions found in version 2.0 of the handbook are supported by current clinical evidence.

Recommendations for infants and children

• Infants younger than 12 months of age should not be treated for acute asthma as acute wheeze in this age group is most likely due to viral bronchiolitis. Other possible alternative diagnoses include tracheobronchomalacia, airway lesion, cardiac left-to-right shunt, and an inhaled foreign body (if wheeze is unilateral). It is recommended to seek the advice of a paediatrician or paediatric respiratory physician before β₂ agonists or corticosteroids (inhaled or systemic) are administered to an infant;
• Loading doses are no longer recommended for systemic corticosteroids in children. This change has occurred as the loading doses typically used are not well supported by the current evidence. Avoidance of these higher initial doses is advised in order to reduce systemic corticosteroid exposure; and
• Paediatric use of antibiotics, proton pump inhibitors and antacids should be restricted to cases where a clinical benefit is likely. Current evidence suggests a possible association between the use of these medications (particularly during the first six months of infancy) and an increased risk of developing asthma and allergic diseases. A large retrospective study demonstrates a greater than two-fold risk of developing asthma in childhood when antibiotics are prescribed in the first six months of life. The adjusted hazard ratios for acid-suppressing medications was somewhat lower at 1.25 for H₂ antagonists and 1.41 for proton pump inhibitors.

Recommendations during pregnancy

• The latest version of the handbook stresses that the unnecessary use of antibiotics during pregnancy must be avoided. Emerging evidence suggests that the maternal microbiome may influence the development of the foetal immune system and possibly play a role in the prevention of allergy-prone phenotypes. Research is continuing in this area to explore possible confounders such as the timing of antibiotic therapy, the spectrum of antibiotic used, and the indication for antibiotic treatment; and
• Women who are pregnant or planning to become pregnant should follow current national guidelines for vitamin D supplementation. Available evidence suggests that adequate vitamin D during pregnancy may reduce the risk of asthma and recurrent wheeze in the offspring.

Changes in the management of exacerbations

• Oral dexamethasone has been added as an alternative to oral prednisolone. Current clinical evidence demonstrates that oral dexamethasone is as effective as prednisolone in adults and children for the treatment of acute asthma. Dexamethasone is a potent corticosteroid with a glucocorticoid activity around six times greater than prednisolone. However, dexamethasone displays only negligible mineralocorticoid activity which translates to fewer adverse effects related to sodium retention. The half-life of dexamethasone is considerably longer than prednisolone (36-72 hours compared to 12-36 hours) which may improve compliance as shorter courses are required. Oral dexamethasone treatment is not recommended to exceed two days duration;
• Ipratropium has been added to the routine treatment of children and adults with severe or life-threatening acute asthma. Clinical studies demonstrate that the use of ipratropium with an inhaled short-acting β₂ agonist reduces hospitalisation in adults with severe acute asthma and children with moderate to severe acute asthma compared to a β₂ agonist alone. While this combination is often well tolerated, it may be associated with a higher incidence of adverse effects such as tremor, agitation, and palpitations;
• Risk factors for poor outcomes have been added to the criteria for hospital admission in addition to the patient’s clinical status after treatment. This includes factors such as a history of ICU admission for asthma, presentation for acute asthma within the past four weeks, and recent high use of β₂ agonists. This revision aims to encourage a more comprehensive assessment of risk and reduce the risk of life-threatening relapse shortly after discharge from hospital; and
• Expansion of recommendations to prescribe inhaled corticosteroids at discharge to reduce the risk of future acute exacerbations. If an inhaled corticosteroid has already been prescribed, hospital admission is an opportune time to check adherence and inhaler technique. Regular inhaled corticosteroid therapy is indicated for adults and adolescents over 12 years of age who have had an asthma exacerbation in the previous 12 months and for those whose asthma is not well controlled (i.e. asthma symptoms twice or more during the previous month or waking due to symptoms once or more during the past month).

Optimal therapy including regular preventative medications (where indicated), timely and appropriate treatment of exacerbations, and management of modifiable risk factors can reduce the morbidity and mortality associated with this chronic disease. For a comprehensive review of all recent updates, please refer to the Australian Asthma Handbook.