Improvement in FEV1 ≥ 12% or 200ml predicted after inhalation of 400mcg salbutamol OR Diurnal variation in PEF: amplitude % mean of twice daily PEF > 8% OR Decrease in FEV1 ≥ 12% and >200ml within 4 weeks after tapering treatment with one or more of the following drugs: ICS, OCS, LABA, SABA PLUS A history of wheeze occurring spontaneously or on exertion.