How is the minimum effective dose achieved?

Minimum effective dose is achieved through ongoing assessment of asthma control. Both symptoms and spirometry should be used to monitor treatment,¹⁷ so that dose reductions take place against a background of stable asthma. Asthma control should be reassessed at every visit, by asking about recent symptoms and reliever use. For example, ask:^{14, 18}

In the last 3-4 weeks:

• On average, how often have you been using your reliever each week?
• Have your asthma symptoms been waking you at night?
• Has your asthma been interfering with your usual activities (work, school, exercise)?
• Have you required any urgent medical care or hospital visits because of asthma symptoms?

Continual reassessment of each patient's asthma to achieve minimal effective dose will avoid two important problems:

• Long-term use of unnecessarily high ICS doses, which increases the risk of adverse effects.
• Failure to detect remission of asthma (especially in children). If dose reduction is not attempted, a child may continue to take ICS for years after ceasing to have asthma.

Stepdown approach

Stepping down the dose of ICS in patients with chronic stable asthma can reduce the amount of steroid taken (and thereby reduce the risk of adverse effects) without  compromising asthma control.¹³ A recent 12-month study compared treatment with high-dose ICS (at least 800 mcg BDP or equivalent) with a 50% reduction in the ICS dose.¹³ Both groups had similar rates of asthma exacerbations, similar numbers of visits to general practice or hospital, as well as similar measures of health status. Adopting a stepdown approach to management supports the recommendations of Australian and international asthma guidelines and facilitates the use of the minimum effective dose.

Role of long-acting beta₂ agonists

The addition of a LABA to low to moderate doses of ICS significantly improves lung function, symptoms and quality of life and reduces the rate of mild and severe asthma exacerbations to a greater degree than increasing the dose of ICS alone.^19-21 Adding a LABA may also facilitate a further reduction in the dose of ICS while maintaining asthma control. For more information, visit the NAC website for a copy of the information paper entitled Combination Therapy: Its Role in Asthma Management (www.NationalAsthma.org.au).