Categorical data are presented as proportions and numbers. Continuous data are either presented as Median + Interquartile range (IQR) or Mean + standard deviation (SD). †: In the preceding 12 months prior to biologic approval. ‡: at WATCH enrolment. §:at baseline biologic visit. Exacerbations: incidence of exacerbations requiring OCS / increase in maintenance OCS in the past 12 months before biologic approval. AHE: acute healthcare encounters, which include Emergency department/ hospital admissions. EOS: eosinophils. µL: microlitre. ACQ6: Asthma Control Questionnaire 6. FENO: fractional exhaled nitric oxide. ppb: parts per billion. IgE: immunoglobulin E. kU/L: kilounits per litre. OCS: oral corticosteroids. mg: milligrams. FEV₁: forced expiratory volume in one second. Adult-onset: Age of asthma onset ≥18 years. GORD: Gastrointestinal reflux disease. SPT: skin prick test. sIgE: specific IgE. ICU: intensive care unit. ILO: intermittent laryngeal obstruction. ABPA: allergic bronchopulmonary aspergillosis. COPD: chronic obstructive pulmonary disease. OSA: obstructive sleep apnoea. The severe asthma, non-biologic (SNB) group is a common comparator group extracted from WATCH. They were participants who either had ≥4 exacerbations or ≥1 AHE or were on maintenance OCS in the past year but did not commence biologic therapy during the study period. Unpaired t-tests, Mann-Whitney U test, Chi-square tests or Fisher’s exact tests were used, where appropriate, to calculate P-values.