Medicare Fee-for-Service (FFS) beneficiaries were associated with a 10-times higher risk for acute ischemic stroke (AIS) within the first 3 days of COVID-19 diagnosis, according to results of a self-controlled case series study published in Neurology.
Several studies have linked SARS-CoV-2 with increased risk for cerebrovascular events. In order to assess the timing of onset in a large population, data were sourced from the Medicare FFS database. Real-time Medicare Geographic Variation (GV) files were used to identify patients (N=37,379) who were diagnosed with COVID-19 between January 2020 and February 2021 as inpatients (Part A) or outpatients (Part B) had an AIS hospitalization were assessed for timing of AIS onset.
Patients were aged median 80.4 (95% CI, 73.5-87.1) years, 56.7% were women, 75.9% were White, 34.0% had a history of stroke, and 28.5% died before the end of follow-up.
Stratified by day, the highest risk was observed at days 0-3 after COVID-19 diagnosis (adjusted incidence rate ratio [aIRR], 10.3; 95% CI, 9.86-10.8) followed by 7-1 day before diagnosis (aIRR, 1.91; 95% CI, 1.78-2.05) and 4-7 (aIRR, 1.61; 95% CI, 1.44-1.80), 8-14 (aIRR, 1.44; 95% CI, 1.32-1.57), and 15-28 (aIRR, 1.09; 95% CI, 1.02-1.18) days after diagnosis.
In a subanalysis which removed day 0, the increased risk for AIS was shifted to the 7 days before COVID-19 diagnosis (aIRR, 5.60; 95% CI, 5.37-5.83), decreasing to 1.77 (95% CI, 1.57-2.01) at days 1-3 and was lowest at days 15-28 (aIRR, 1.09; 95% CI, 1.01-1.17).
The observed association was stronger among younger patients (aged 65-74 years), in which the aIRR at days 0-3 was 14.7 (95% CI, 13.6-15.8) compared with 7.04 (95% CI, 6.46-7.66; P <.001) among those aged ³85 years.
Risk for AIS was more pronounced among patients without a history of stroke (aIRR, 14.6; 95% CI, 13.9-15.4) than those with a stroke history (aIRR, 7.92; 95% CI, 7.26-8.63).
This study may have been limited by timing, especially at the beginning of the pandemic, in which there was limited testing for COVID-19 and turnaround time varied.
“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 researchers concluded.
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. Published online February 3, 2022. doi:10.1212/WNL.0000000000013184