An Increased Risk for Ischemic Stroke in the Short-Term Period following COVID-19 Infection: A Nationwide Population-Based Study

Introduction: The association disclosed between coronavirus disease 2019 (COVID-19) infection and ischemic stroke (IS) raises concern. The exact risk periods, which were not consistent between studies, require further investigation. Methods: We linked two national databases: the COVID-19 database and the Israeli National Stroke Registry. The self-controlled case series method was used to estimate the association between COVID-19 infection and a first IS. The study population included all Israeli residents who had both a first IS event and a first COVID-19 diagnosis during 2020. The date of the PCR test served to define the day of exposure, and the 28 days following it were categorized into three risk periods: days 1-7, 8-14, and 15-28. A relative incidence (RI) with a 95% confidence interval (95% CI) was calculated based on the incidence rate of events in a post-exposure period, compared to the incidence rate in a control period. Results: From January 1, 2020, to December 31, 2020, 308,015 Israelis aged 18+ were diagnosed with COVID-19 and 9,535 were diagnosed with a first IS. Linking the two databases, 555 persons had both diagnoses during 2020. The mean age of the study population was 71.5 ± 13.7, 55.1% were males, 77.8% had hypertension, 73.7% had hyperlipidemia, 51.9% had diabetes, and 28.5% had ischemic heart disease. Comparing the risk period and the control period, we found a very similar distribution of the cardiovascular risk factors. The risk for an acute IS was 3.3-fold higher in the first week following COVID-19 diagnosis, compared with a control period (RI = 3.3; 95% CI: 2.3-4.6). The RI among males (RI = 4.5; 95% CI: 2.9-6.8) was 2.2-fold higher compared to females. The increased risk did not last beyond the first week following exposure. Conclusion: Physicians should be aware of the elevated risk for IS among patients experiencing COVID-19, particularly among men with high burden of cardiovascular risk factors.