Purpose: Asthma control is multifaceted, involving symptoms and risk of adverse outcomes. Emerging evidence suggests a bidirectional link between poor asthma control and severe COVID-19, but large studies addressing all components of asthma control in this context are lacking. Our aims were to evaluate if 1) uncontrolled asthma was a risk factor for COVID-19 hospitalization and death, 2) asthma control changed during the pandemic and 3) COVID-19 hospitalization was a risk factor for future uncontrolled asthma. Methods: Patients with asthma (n = 125,362) were identified in the Swedish National Airway Register from January 2014 to 2020, whereof n = 2377 were hospitalized and n = 305 died due to COVID-19 during follow-up until December 2022. Asthma control was evaluated by symptoms (Asthma Control Test (ACT) ≥ 20: well controlled, ACT 16– 19 not well-controlled and ACT < 16 very poorly controlled asthma), lung function (FEV 1 % predicted (pp)) and frequent and/or severe exacerbations (dispensed oral corticosteroids and asthma inpatient care). Results: ACT 16– 19 (RR 1.57, 95% CI 1.34– 1.84), ACT < 16 (1.72, 1.46– 2.02), FEV 1 < 80pp (1.29, 1.13– 1.48), frequent (1.99, 1.79– 2.21) and severe exacerbations (2.54, 2.09– 3.08) were associated with a higher risk for COVID-19 hospitalization. COVID-19 death was associated with ACT < 16, frequent and severe exacerbations. Overall, at follow-up, proportions of ACT < 20 (36.1%) and FEV 1 < 80pp (48.3%) were stable, while exacerbations decreased (frequent; 7.9% to 6.8%, severe; 1.3% to 0.4%). COVID-19 hospitalization was a risk factor for frequent (1.35, 1.22– 1.51) and severe (3.42, 1.22– 1.51) future asthma exacerbations. Conclusion: All dimensions of poor asthma control were associated with an increased risk of severe COVID-19. In contrast, only exacerbation risk was elevated following COVID-19. Plain Language Summary: Poor asthma control may increase the risk of severe COVID-19, and severe COVID-19 may also affect asthma afterwards. This has not been studied in a large group before. We analyzed data from over 125,000 patients with asthma in Sweden. We found that patients who, at the start of the study, had poor symptom control, reduced lung function, or had experienced asthma flare-ups in the past were more likely to develop severe COVID-19 later on. During the pandemic, symptom control and lung function stayed stable, while flare-ups decreased. However, patients who had been hospitalized for COVID-19 experienced more flare-ups afterwards, compared to those who had not been hospitalized. Keywords: asthma control, asthma control test, ACT, COVID-19, exacerbation, lung function
Selberg et al. (Sun,) studied this question.