An observational Swedish study yesterday in BMJ reveals an elevated risk of serious blood clots and abnormal bleeding up to 6 months after recovery from COVID-19.A team led by Umea University researchers analyzed data from national registries in Sweden to follow 1,057,174 people diagnosed as having COVID-19 and 4,076,342 matched, uninfected controls from Feb 1, 2020, to May 25, 2021.
They used a self-controlled case series (up to 6 months after diagnosis) and matched-cohort study design (first 30 days).Thirty-seven cases were likely reinfections.
Average patient age was 40.2 years, and 51% were women.Leg, lung blood clots, bleedingIn the case series, incidence rate ratios (IRRs) rose significantly 70 days after COVID-19 diagnosis for deep vein thrombosis (blood clot in a leg), after 110 days for pulmonary embolism (blood clot in a lung), and after 60 days for abnormal bleeding.
Patients with mild cases also were at increased risk for clots but not bleeding.In the 6 months after diagnosis, 1,761 participants had a first deep vein thrombosis, 3,267 had a first pulmonary embolism, and 7,927 had major bleeding for the first time.