The impact of national lockdown in 2020 on admission rates for exacerbations in asthma; a nationwide cohort study.

Abstract

<b>Background:</b> Social distancing measures introduced during the COVID-19 pandemic have reduced admission rates for a variety of respiratory tract infections. We hypothesized that rates of asthma exacerbations would decline following the national lockdown introduced on March 12, 2020, in Denmark. <b>Aim:</b> To determine weekly rates of in- and out of hospital asthma exacerbations prior to and during the national lockdown. <b>Methods:</b> All persons &gt;18 years with at least one outpatient hospital contact with asthma as the primary diagnosis from January 1, 2013, to December 31, 2017, were included. Weekly asthma exacerbation rates from January 1, 2018, to May 22, 2020, were assessed. An interrupted time-series (ITS model) with March 12, 2020, as the point of interruption was conducted. <b>Results:</b> A total of 38,225 patients with asthma were identified. The ITS model showed no immediate changes in exacerbation rates during the first week after March 12, 2020. However, there was a significant decrease in weekly exacerbation rates in the following 10 weeks (change in trend for exacerbations requiring hospitalisation: -0.75 [95% CI -1.39,-0.12], (p &lt; 0.02) corresponding to a reduction of about 1 exacerbation per year per 100 patients in the cohort, and a change in trend for all asthma exacerbations: -12.2 [95% CI -19.1,-5.4], p&lt;0.001 corresponding to a reduction of 16.5 exacerbations per year per 100 patients in the cohort). <b>Conclusion:</b> The introduction of the social distancing measures in Denmark on March 12, 2020, did not lead to an immediate reduction in asthma exacerbation rates, however a gradual decline in exacerbation rates during the following 10-weeks period was observed.