Table 2.

Definitions of exacerbation and worsening from examined studies

Outcome: Exacerbation
Acute worsening of asthma symptoms Worsening of asthma which requires use of SCS and/or hospitalizations and/or emergency department visits ED visit/hospitalization requiring OCS Increased asthma symptoms requiring treatment with OCS or hospitalization	Episodes requiring the use of SCS Exacerbations requiring rescue OCS resulting in: unplanned outpatient visit, use of systemic and/or nebulized inhaled corticosteroids, ED visit, or hospitalization
Outcome: Moderate Exacerbation
Deterioration in asthma symptoms, deterioration in lung function, or increased rescue bronchodilator use lasting for ≥2 days SCS use ≥3 days as outpatient or ≤24 h during ED visit	Worsening asthma requiring ≥10 mg prednisone (or equivalent glucocorticoid treatment) above baseline for ≥3 days, OR an unscheduled provider visit or hospitalization associated with an increase in asthma therapy that did not qualify for severe clinical asthma exacerbation
Outcome: Severe Exacerbation
Exacerbations requiring SCS treatment for ≥3 days, and/or ED visit or hospitalization for acute asthma Exacerbations requiring ED visits or short-course SCS Worsening of asthma which requires use of SCS and/or hospitalization and/or ED visits Worsening asthma requiring ≥10 mg prednisone (or equivalent glucocorticoid treatment) above baseline for ≥3 days, AND an unscheduled provider visit or hospitalization associated with an increase in asthma therapy that did not qualify for severe clinical asthma exacerbation SCS use ≥3 days and hospitalization or emergency department visit (≥24 h) or death due to asthma	An exacerbation resulting in ≥1 of the following: A temporary bolus/burst of SCS for ≥3 consecutive days to treat symptoms of asthma worsening (a single depo-injectable dose of corticosteroids will be considered equivalent) An ED or urgent care visit (< 24 hours in the facility for evaluation and treatment) due to asthma that required SCS An in-patient hospitalization (admission and/or ≥ 24 hours in a healthcare facility) Asthma requiring the use of SCS, or an increase from a stable maintenance dose, for ≥ 3 days or an inpatient hospitalization or ED visit due to asthma that required SCS Hospital admissions or treatment with a course of OCS
Outcome: Asthma Worsening
Asthma worsening is defined as at least one of the following: PEF ≤ 75% of baseline FEV1 < 80% of baseline; Increase in rescue medication use of ≥6 puffs per day compared to baseline Increase in ACQ-5 score of ≥ 0.5 compared to baseline The occurrence of a severe asthma exacerbation Asthma worsening is defined as one or more of the following: An increase in ACQ-6 >0.5 from baseline A daily asthma symptom score of ≥4 for 2 consecutive days Nocturnal awaking(s) due to asthma requiring SABA use on 2 consecutive nights An increase from baseline of ≥4 puffs per day of rescue medication use on 2 consecutive days, ≥20% reduction in morning PEF from baseline and ≥20% reduction in evening PEF from baseline for 2 consecutive days Visit to ED, hospitalization or OCS therapy for severe asthma exacerbation	A day with worsening asthma was defined as any day during which any of the following occurred: A decrease from baseline in morning PEF > 20% Morning PEF < 180 liters/minute An increase in β-agonist use of > 70% (and a minimum increase of at least 2 puffs) An increase from baseline in daytime asthma symptom score of > 50% An asthma attack, as defined by any day when ≥one of the following events due to asthma has occurred: SCS use, unscheduled visit to the doctor or urgent care clinic, unscheduled visit to ED, and/or hospitalization.

ED: Emergency Department, SCS: Systemic corticosteroids, OCS: Oral corticosteroids, PEF: Peak expiratory flow, FEV1: Forced expiratory volume in 1 second, ACQ: Asthma Control Questionnaire, SABA: Short-acting beta agonist