- At last one documented asthma exacerbation (defined as increase asthma symptoms requiring systemic corticosteroid rescue therapy) that requires visits to the emergency room or to be hospitalized in the past 12 months. It is also considered asthma exacerbation a non-planned visit that required rescue medication (β2-agonists and/or steroid nebulization every 20 minutes or β2-agonists inhaler shots every 20 minutes).