Pulmonary embolism and deep venous thrombosis after COVID-19: long-term risk in a population-based cohort study

BACKGROUND: Venous thromboembolism (VTE) (pulmonary embolism [PE] or deep venous thrombosis [DVT]) is common during acute COVID-19. Long-term excess risk has not yet been established. OBJECTIVES: To study long-term VTE risk after COVID-19. METHODS: Swedish citizens aged 18 to 84 years hospitalized and/or testing positive for COVID-19 between January 1, 2020, and September 11, 2021 (exposed), stratified by initial hospitalization, were compared to matched (1:5), nonexposed, population-derived subjects without COVID-19. Outcomes were incident VTE, PE, or DVT recorded within 60, 60 to <180, and ≥180 days. Cox regression was used for evaluation, and a model adjusted for age, sex, comorbidities, and socioeconomic markers was developed to control for confounders. RESULTS: Among exposed patients, 48,861 were hospitalized for COVID-19 (mean age, 60.6 years) and 894,121 were without hospitalization (mean age, 41.4 years). Among patients hospitalized for COVID-19, fully adjusted hazard ratios during 60 to <180 days were 6.05 (95% CI, 4.80-7.62) for PE and 3.97 (CI, 2.96-5.33) for DVT compared with that for nonexposed patients with corresponding estimates among those with COVID-19 without hospitalization 1.17 (CI, 1.01-1.35) and 0.99 (CI, 0.86-1.15), based on 475 and 2311 VTE events, respectively. Long-term (≥180 days) hazard ratios in patients hospitalized for COVID-19 were 2.01 (CI, 1.51-2.68) for PE and 1.46 (CI, 1.05-2.01) for DVT, while nonhospitalized patients had similar risk as nonexposed patients, based on 467 and 2030 VTE events, respectively. CONCLUSION: Patients hospitalized for COVID-19 retained an elevated excess risk of VTE, mainly PE, after 180 days, while long-term risk of VTE in individuals with COVID-19 without hospitalization was similar to that in the nonexposed patients.