COVID-19 and risk of acute ischemic stroke among medicare beneficiaries: Self-controlled case series study

ABSTRACT

Introduction: 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 COVID19 and risk of acute ischemic stroke (AIS). Methods: We included 19,553 Medicare fee-for-service (FFS) beneficiaries aged ≥65 years diagnosed with COVID-19 between April 1 and November 30, 2020 and AIS hospitalization from January 1, 2019 through November 30, 2020. We used a self-controlled case series design 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. Results: Among 19,553 Medicare FFS beneficiaries with COVID-19 and AIS, the median age at diagnosis of COVID-19 was 80.5 (interquartile range 73.6-87.3) years and 57.5% were women. IRRs at 0-3, 4-7, 8-14, and 15-28 days following COVID-19 diagnosis were 10.97 (95% confidence interval 10.30-11.68), 1.59 (1.35-1.87), 1.23 (1.07-1.41), and 1.06 (0.95-1.18), 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. Conclusions: Risk of AIS among Medicare FFS beneficiaries was ten times 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.