Cerebral venous thrombosis: a retrospective cohort study of 513,284 confirmed COVID-19 cases and a comparison with 489,871 people receiving a COVID-19 mRNA vaccine

Abstract

Objectives To estimate the absolute risk of cerebral venous thrombosis (CVT) and portal vein thrombosis (PVT) in the two weeks following a diagnosis of COVID-19, and to assess the relative risks (RR) compared to influenza or the administration of an mRNA vaccine against COVID-19. Design Retrospective cohort study based on an electronic health records network Setting Linked records between primary and secondary care centres within 59 healthcare organisations, primarily in the USA Participants All patients with a confirmed diagnosis of COVID-19 between January 20, 2020 and March 25, 2021 were included (N=537,913, mean [SD] age: 46.2 [21.4] years; 54.9% females). Cohorts (matched for age, sex, and race) of participants diagnosed with influenza (N=392,424) or receiving the BNT162b2 or mRNA-1273 vaccine (N=366,869) were used for comparison. Main outcome measures Diagnosis of CVT (ICD-10 code I67.6) or PVT (ICD-10 code I81) within 2 weeks after a diagnosis of COVID-19. Results The incidence of CVT after COVID-19 diagnosis was 42.8 per million people (95% CI 28.5–64.2) including 35.3 per million (95% CI 22.6–55.2) first diagnoses. This was significantly higher than the CVT incidence in a matched cohort of patients with influenza (RR=3.83, 95% CI 1.56–9.41, P<0.001) and people who received an mRNA vaccine (RR=6.67, 95% CI 1.98–22.43, P<0.001). The incidence of PVT after COVID-19 diagnosis was 392.3 per million people (95% CI 342.8–448.9) including 175.0 per million (95% CI 143.0–214.1) first diagnoses. This was significantly higher than the PVT incidence in a matched cohort of patients with influenza (RR=1.39, 95% CI 1.06–1.83, P=0.02) and people who received an mRNA vaccine (RR=7.40, 95% CI 4.87–11.24, P<0.001). Mortality after CVT and PVT was 17.4% and 19.9% respectively. Conclusions The incidence of CVT and PVT is significantly increased after COVID-19. The data highlight the risk of serious thrombotic events in COVID-19 and can help contextualize the risks and benefits of vaccination in this regard.