Uncontrolled asthma associates with hospitalization and death due to COVID-19: a nationwide longitudinal study

<bold>Background:</bold> Uncontrolled asthma was a predictor for severe COVID-19 during the first wave of the pandemic. However, the conditions of the pandemic change over time, therefore longitudinal studies are needed. <bold>Aim:</bold> To study the association between asthma control and hospitalization and death due to COVID-19. <bold>Methods:</bold> We identified 89959 asthma patients ≥ 18 years with an Asthma Control Test (ACT) in the Swedish National Airway Register 2015-2020 (index-date). Uncontrolled asthma was defined as ACT <20, and very poorly controlled asthma as ACT <16. Doses of inhaled corticosteroids (ICS) and medication-treated comorbidities were identified by ATC-codes from the National Prescribed Drug Register within one year before the patient's index-date. Hospitalization and death due to COVID-19 were identified from the mandatory national registers by ICD-10 codes until 31 Dec 2022. <bold>Results:</bold> Uncontrolled asthma was identified in 43% (n=38364) of patients, and among these 48% (n=18338) had very poorly controlled asthma. Independently of sex, age, dose of ICS, cardiovascular disease and diabetes, uncontrolled asthma and very poorly controlled asthma was associated with hospitalization (OR 1.47, 95% CI: 1.27- 1.70 and OR 1.98, 95% CI 1.73- 2.27) and death due to COVID-19 (OR 1.98, 95% CI 1.26- 3.13 and OR 2.83, 95% CI 1.86- 4.31), respectively. <bold>Conclusions:</bold> Uncontrolled asthma, assessed by ACT, is associated with hospitalization and death due to COVID-19. Nurses play an important role in the management of asthma where ACT is a recommended tool. ACT allows for the identification of patients at higher risk of poor outcomes.