| Cross-sectional case-control studies  

COVID-19 and Risk of Acute Ischemic Stroke Among Medicare Beneficiaries Aged 65 Years or Older: Self-Controlled Case Series Study

Findings of association between COVID-19 and stroke remain inconsistent, ranging from significant association, absence of association to less than expected ischemic stroke among hospitalized patients with COVID-19.

The present study examined the association between COVID-19 and risk of acute ischemic stroke (AIS). The authors included 37,379 Medicare fee-for-service (FFS) beneficiaries aged ≥65 years diagnosed with COVID-19 from April 1, 2020 through February 28, 2021 and AIS hospitalization from January 1, 2019 through February 28, 2021. A self-controlled case series design was used to examine the association between COVID-19 and AIS and estimated the incident rate ratios (IRR) by comparing incidence of AIS in risk periods (0–3, 4–7, 8–14, 15–28 days after diagnosis of COVID-19) vs. control periods. Among 37,379 Medicare FFS beneficiaries with COVID-19 and AIS, the median age at diagnosis of COVID-19 was 80.4 (interquartile range 73.5–87.1) years and 56.7% were women. When AIS at day of exposure (day=0) included in the risk periods, IRRs at 0–3, 4–7, 8–14, and 15–28 days following COVID-19 diagnosis were 10.3 (95% confidence interval 9.86–10.8), 1.61 (1.44–1.80), 1.44 (1.32–1.57), and 1.09 (1.02–1.18); when AIS at day 0 excluded in the risk periods, the corresponding IRRs were 1.77 (1.57–2.01) (day 1-3), 1.60 (1.43–1.79), 1.43 (1.31–1.56), and 1.09 (1.01–1.17), respectively. The association appeared to be stronger among younger beneficiaries and among beneficiaries without prior history of stroke but largely consistent across sex and race/ethnicities. The risk of AIS among Medicare FFS beneficiaries was ten times (day 0 cases in the risk period) as high during the first 3 days after diagnosis of COVID-19 as during the control period and the risk associated with COVID-19 appeared to be stronger among those aged 65–74 years and those without prior history of stroke. The authors concluded that this study provides Class IV evidence that SARS-CoV-2 infection, the virus that causes COVID-19, is associated with increased risk of AIS in the first three days after diagnosis in Medicare FFS beneficiaries ≥ 65 years age.
Yang Q, Tong X, George MG, Chang A, Merritt RK. COVID-19 and Risk of Acute Ischemic Stroke Among Medicare Beneficiaries Aged 65 Years or Older: Self-Controlled Case Series Study. Neurology. 2022 Feb 3:10.1212/WNL.0000000000013184.

doi: 10.1212/WNL.0000000000013184.