An increased risk for ischemic stroke in the short-term period following COVID-19 infection

BACKGROUND: The association disclosed between 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 between two national databases: the national 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 01-January-2020 to 31-December-2020, 308,015 Israelis aged 18+ were diagnosed with COVID-19 and 9,535 were diagnosed with a first IS. Linking between 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, 28.5% had ischemic heart disease and 25.6% had atrial fibrillation. Comparing between 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. CONCLUSIONS: 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. KEY MESSAGES: • Risk for an ischemic stroke is elevated in COVID-19 patients upon infection. • This finding was particularly evident in men with cardiovascular risk factors.