Compatible clinical history plus either/or,
• FEV, ≥12% (and 200 mL) increase following administration of a bronchodilator/ trial of glucocorticoids. Greater confidence is gained if the increase is >15% and >400 mL
>20% diurnal variation on ≥3 days in a week for 2 weeks on PEF diary
• FEV, ≥15% decrease after 6 mins of exercise