Over the past 20 years, inhaled corticosteroids have become established as cornerstone therapy in the treatment of obstructive pulmonary disorders, ranging from asthma and chronic obstructive pulmonary disease to cystic fibrosis.

The appropriate use of inhaled corticosteroids has transformed the management of asthma in children, improving the quality of life of children and their families, improving exercise tolerance, and reducing hospitalisation and mortality rates. Asthma mortality rates in Australia have fallen by more than 50% over the past 12 years, in parallel with our increased use of inhaled corticosteroids and the development of clinical guidelines.1

We have gained confidence in the safety of inhaled steroids at recommended doses, supported by national guidelines and extensive reviews.2 Local side effects, including oropharyngeal candidiasis and laryngeal dysfunction, can usually be controlled with the use of spacer devices. Further, at recommended doses, initial concerns about growth failure and impaired bone mineralisation have not been realised.2

In recent years, with the advent of more potent steroids and more efficient delivery systems, the relative doses commonly used have increased. There have been several reports of serious adverse events resulting from doses of inhaled corticosteroids in excess of those recommended. These include growth failure,3 and suppression of the hypothalamic–pituitary–adrenal axis4-6 — resulting in acute hypoglycaemia, altered consciousness and coma, convulsions7,8 and death.9 While the majority of these effects have been reported at higher doses, some have occurred at a dose within the recommended range, suggesting that individual susceptibility may also be important. These effects are more commonly associated with one potent inhaled corticosteroid, but this is probably a result of over-representation of that drug in the higher dosage range. Comparative studies would suggest that this is a class effect of inhaled corticosteroids.4

Are we overusing inhaled corticosteroids? New evidence-based National Asthma Council guidelines define the need for inhaled corticosteroids in asthma. They recommend an upper limit of 500 μg per day of fluticasone propionate (or equivalent) in children, and 1000 μg per day in adults with severe asthma. In support, a recent meta-analysis, examining the dose response to inhaled corticosteroids in adolescents and young adults, reported that 90% of the maximum benefit was achieved at a daily dose equivalent to 250 μg fluticasone propionate.10 Minimal further improvement resulted from increases up to 600 μg/day. The introduction of long-acting β-agonists at low doses of inhaled corticosteroids can achieve improved asthma control, avoiding the need for higher doses of inhaled corticosteroids.

When asthma is not controlled by a dose of inhaled corticosteroids equivalent to 500 μg/day fluticasone propionate and long-acting β-agonists, consideration should be given to issues of adherence to the treatment regimen, inhaler technique or an alternative diagnosis. In the UK survey of adrenal crisis due to inhaled corticosteroids,9 three of the 28 children did not have asthma and, in five, asthma did not account for all the respiratory symptoms. Inhaled steroids have been shown to be ineffective in children with recurrent cough and those with episodic viral-associated wheeze. Clinicians should be alert to the clinical features of hypoadrenalism, particularly when precipitated at a time of metabolic stress, perhaps indicating adrenal crisis. Children taking excessive doses of inhaled corticosteroids (> 500 μg/day fluticasone propionate) should have their hypothalamic–pituitary–adrenal axis assessed, and their parents should be informed of the risks and the potential need for systemic corticosteroid cover during intercurrent illness and surgery.

The National Asthma Council recommends the introduction of inhaled corticosteroids (alone or in combination) to gain control of symptoms. On clinical review, there should be a reduction (ie, back-titration) to an appropriate dose to optimise symptom control and reduce the likelihood of adverse effects. By comparison with their United States and European counterparts, Australian prescribers have used higher doses of inhaled corticosteroids, but there is now a clear incentive to reverse this trend.

The availability of effective anti-inflammatory therapy, useful and well-publicised guidelines, as well as incentive payments to general practitioners for the treatment of moderate to severe asthma under the 3+ Visit Plan (http://www.health.gov.au/pq/asthma/3plusgp.htm), should pave the way for greater improvements in the management of asthma. The goal of asthma management is to achieve optimal control of asthma symptoms with the lowest effective medication dose, allowing children to enjoy a normal quality of life neither burdened by, nor at risk of, serious adverse events. Inhaled corticosteroids remain the cornerstone of asthma management. Responsible use of inhaled corticosteroids will reinforce confidence in the consumer, whereas irresponsible use will promote steroid phobia — a significant barrier to adherence.