Change in Exacerbation Rate of Asthma Patients before and after COVID-19 Infection.

Background: Coronavirus disease 2019 (COVID-19) significantly impacted healthcare utilization and disease outcomes worldwide. During the pandemic, overall asthma exacerbations reportedly declined; however, the specific effect of COVID-19 infection on subsequent exacerbation patterns in asthma patients remains unclear.

Methods: Using a nationwide health insurance claims database from South Korea, we identified patients who had both asthma and a confirmed COVID-19 diagnosis in 2020. We defined the pre-COVID-19 period as the 12 months immediately preceding the date of each patient's COVID-19 diagnosis, and the post-COVID-19 period as the 12 months following that date. Baseline characteristics, annual exacerbation rates, and direct medical costs were compared between these two timeframes.

Results: Among 82,825 confirmed COVID-19 cases, 2,965 patients with asthma met the inclusion criteria. Compared to the pre-COVID-19 period, the proportion of patients experiencing moderate and moderate-to-severe exacerbations decreased, whereas after COVID-19 infection, severe exacerbations increased. A binomial mixed model showed that moderate and moderate-to-severe exacerbations declined significantly (incidence rate ratio [IRR]=0.848, p<0.001; and IRR=0.912, p<0.001, respectively), while after COVID-19 infection, severe exacerbations increased (IRR=1.220, p<0.001). Of those who were non-exacerbators prior to COVID-19, 10.8% became exacerbators. This group was older, more frequently male, and had a greater comorbidity burden. Total direct medical costs escalated markedly from USD (2,965.50 to 4,850.41; p<0.001), particularly among those who developed as exacerbators after COVID-19 infection.

Conclusion: COVID-19 infection had a paradoxical impact on asthma exacerbations, reducing moderate exacerbations, while increasing severe events. The substantial rise in medical costs contributes to the economic burden of asthma care.