(i) prior diagnosis of asthma made by a physician; OR (ii) prior documented episode of acute cough, wheezing and/or dyspnea with significant response to inhaled β2-agonists or to oral corticosteroids; OR (iii) in a child aged <2 years, 3 or more episodes of cough, wheezing and/or dyspnea, including the index visit; OR (iv) previous lung function tests showing significant reversibility post-bronchodilation (≥12% FEV1 or ≥25% Rrs at 4 to 8 Hz); OR (v) a positive provocation test (PC20 ≤8 mg/mL or Provocation Dose (to increase Rrs by 50% or more (PD50) ≤8 mg/mL), OR (vi) the current episode diagnosed or suspected of asthma by the emergency physician?