Table 5.

Changes in lung function consistent with a diagnosis of asthma

• Improvement in FEV1 by ≥ 15% and ≥ 200 ml (or in peak expiratory flow of ≥ 20% and ≥ 60 l/min) 20 minutes after taking 400 μg (2 puffs) inhaled salbutamol or 2.5 mg nebulised salbutamol

• Improvement in FEV1 by ≥ 15% and ≥ 200 ml (or in peak expiratory flow of ≥ 20% and ≥ 60 l/min) after taking 30 mg oral prednisolone for two weeks

• Variability in peak expiratory flow (difference between highest and lowest scores) of ≥ 20% during three consecutive days over two weeks