All-cause mortality and location of death in patients with established cardiovascular disease before, during, and after the COVID-19 lockdown: a Danish Nationwide Cohort Study

Background: On 13 March 2020, the Danish authorities imposed extensive nationwide lockdown measures to prevent the spread of the coronavirus disease 2019 (COVID-19) and reallocated limited healthcare resources. We investigated mortality rates, overall and according to location, in patients with established cardiovascular disease before, during, and after these lockdown measures.

Methods and results: Using Danish nationwide registries, we identified a dynamic cohort comprising all Danish citizens with cardiovascular disease (i.e. a history of ischaemic heart disease, ischaemic stroke, heart failure, atrial fibrillation, or peripheral artery disease) alive on 2 January 2019 and 2020. The cohort was followed from 2 January 2019/2020 until death or 16/15 October 2019/2020. The cohort comprised 340 392 and 347 136 patients with cardiovascular disease in 2019 and 2020, respectively. The overall, in-hospital, and out-of-hospital mortality rate in 2020 before lockdown was significantly lower compared with the same period in 2019 [adjusted incidence rate ratio (IRR) 0.91, 95% confidence interval (CI) CI 0.87-0.95; IRR 0.95, 95% CI 0.89-1.02; and IRR 0.87, 95% CI 0.83-0.93, respectively]. The overall mortality rate during and after lockdown was not significantly different compared with the same period in 2019 (IRR 0.99, 95% CI 0.97-1.02). However, the in-hospital mortality rate was lower and out-of-hospital mortality rate higher during and after lockdown compared with the same period in 2019 (in-hospital, IRR 0.92, 95% CI 0.88-0.96; out-of-hospital, IRR 1.04, 95% CI1.01-1.08). These trends were consistent irrespective of sex and age.

Conclusions: Among patients with established cardiovascular disease, the in-hospital mortality rate was lower and out-of-hospital mortality rate higher during lockdown compared with the same period in the preceding year, irrespective of age and sex.