Background: Meta-analyses of observational studies report a 1.1-1.7% pooled risk of stroke among patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection requiring hospitalization, but consultations for stroke and reperfusion procedures have decreased during the outbreak that occurred during the first half of the year 2020. It is still unclear whether a true increase in the risk of stroke exists among patients with coronavirus disease 2019 (COVID-19). In-hospital ischemic stroke (IHIS) complicated the 0.04-0.06% of all admissions in the pre-COVID-19 era, but its incidence has not been assessed among inpatients with COVID-19. We aimed to compare IHIS incidence among patients with SARS-CoV-2 infection with that of inpatients with non-COVID-19 illnesses from the same outbreak period and from previous periods.
Methods: This historical cohort study belongs to the COVID-19@Vallecas cohort. The incidence of IHIS was estimated for patients with SARS-CoV-2 hospitalized during March-April 2020 [COVID-19 cohort (CC)], for patients with non-COVID-19 medical illness hospitalized during the same outbreak period [2020 non-COVID-19 cohort (20NCC)], and for inpatients with non-COVID-19 illness admitted during March-April of the years 2016-2019 [historical non-COVID-19 cohort (HNCC)]. Unadjusted risk of IHIS was compared between the three cohorts, and adjusted incidence rate ratio (IRR) of IHIS between cohorts was obtained by means of Poisson regression.
Results: Overall, 8126 inpatients were included in this study. Patients in the CC were younger and more commonly men than those from the HNCC and 20NCC. Absolute risk of IHIS was 0.05% for HNCC, 0.23% for 20NCC, and 0.36% for CC, (p = 0.004 for HNCC vs. CC). Cumulative incidence for IHIS by day nine after admission, with death as a competing risk, was 0.09% for HNCC, 0.23% for 20NCC, and 0.50% for CC. In an adjusted Poisson regression model with sex, age, needing of intensive care unit admission, and cohort (HNCC as reference) as covariates, COVID-19 was an independent predictor for IHIS (IRR 6.76, 95% confidence interval 1.66-27.54, p = 0.01). A nonsignificant increase in the risk of IHIS was observed for the 20NCC (IRR 5.62, 95% confidence interval 0.93-33.9, p = 0.06).
Conclusions: SARS-CoV-2 outbreak was associated with an increase in the incidence of IHIS when compared with inpatients from a historical cohort. Viral infection itself may be related to the increased risk of IHIS among patients with COVID-19, but in view of our results from the 20NCC, it is likely that other factors, such as hospital saturation and overwhelming of health systems, may have played a role in the increased frequency of IHIS.
Keywords: COVID-19; Cohort studies; Epidemiology; Incidence; Ischemic stroke; SARS-CoV-2; Stroke.
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