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People with severe COVID-19 are at excess risk for venous thromboembolism (VTE), but whether risk also rises among patients with mild disease is unclear. Using Swedish national health databases, researchers identified more than 1 million people who tested positive for SARS-CoV-2 between February 2020 and May 2021; incidence of first deep venous thrombosis (DVT), pulmonary embolism (PE), and bleeding during the subsequent 180 days was recorded. Controls were a matched cohort of 4 million people who did not have COVID-19.
After adjustment, risks for DVT, PE, and bleeding were significantly higher in the 30 days after diagnosis of COVID-19 compared with no COVID-19 diagnosis (risk ratios: 5, 33, and 2, respectively), and these risks remained significantly elevated for 3, 6, and 2 months, respectively. Risk ratios were elevated primarily in patients who were hospitalized for COVID-19; for patients who were not hospitalized, risks were lower (RRs: 3, 7, and 1, respectively). Absolute risks for all these events were low (e.g., 0.17% for PE in the first 30 days after COVID-19 diagnosis vs. 0.004% for controls).
Katsoularis I et al. Risks of deep vein thrombosis, pulmonary embolism, and bleeding after covid-19: Nationwide self-controlled cases series and matched cohort study. BMJ 2022 Apr 6; 377:e069590. (https://doi.org/10.1136/bmj-2021-069590)
Comment
Because these data were collected before vaccines were widely available, their implications for largely vaccinated populations are uncertain. However, even small increases in absolute risk for thromboembolism (particularly PE) after mild disease might be important in view of continuing surges of COVID-19, with many COVID-19 cases being mild and unreported or undiagnosed. Heightened vigilance probably is warranted.