The association between cardiovascular disease admission rates and the coronavirus disease 2019 lockdown and reopening of a nation: a Danish nationwide cohort study

Aims To investigate the admission rates of cardiovascular diseases, overall and according to subgroups, and subsequent mortality rates during the coronavirus disease 2019 societal lockdown (12 March 2020) and reopening phase (15 April 2020) in Denmark. Methods and results Using Danish nationwide registries, we identified patients with a first-time acute cardiovascular admission in two periods: (i) 2 January-16 October 2019 and (ii) 2 January-15 October 2020. Weekly incidence rates of a first-time cardiovascular admission, overall and according to subtypes, in the two periods were calculated. The incidence rate of first-time cardiovascular admissions overall was significantly lower during the first weeks of lockdown in 2020 compared with a similar period in 2019 but increased after the gradual reopening of the Danish society. A similar trend was observed for all subgroups of cardiovascular diseases. The mortality rate among patients admitted after March 12 was not significantly different in 2020 compared with 2019 [mortality rate ratio 0.98; 95% confidence interval (CI) 0.91-1.06)]. Conclusion In Denmark, we observed a substantial decrease in the rate of acute cardiovascular admissions, overall and according to subtypes, during the first weeks of lockdown. However, after the gradual reopening of the Danish society, the admission rates for acute cardiovascular diseases increased and returned to rates similar to those observed in 2019. The mortality rate in patients admitted with cardiovascular diseases during lockdown was similar to that of patients during the same period in 2019.