(HealthDay News) — Mortality seen in association with vaccine-induced immune thrombocytopenia and thrombosis (VITT) after the first dose of the ChAdOx1 nCoV-19 vaccine (Oxford-AstraZeneca) is increased for those with cerebral venous sinus thrombosis and a low platelet count, according to a study published online Aug. 11 in the New England Journal of Medicine.
Sue Pavord, M.B., Ch.B., from the Oxford University Hospitals NHS Foundation Trust in the United Kingdom, and colleagues conducted a prospective cohort study involving patients with suspected VITT who presented to U.K. hospitals between March 22 and June 6, 2021.
The researchers identified 170 definite and 50 probable VITT cases among 294 patients who were evaluated. The patients had all received the first dose of the ChAdOx1 nCoV-19 vaccine and presented at five and 48 days after vaccination. Patient age ranged from 18 to 79 years, with no sex preponderance and no medical risk factors identified. Mortality was 22 percent overall. The odds of death were increased 2.7-, 1.7-, 1.2-, and 1.7-fold for patients with cerebral venous sinus thrombosis, for every 50 percent decrease in baseline platelet count, for every increase of 10,000 fibrinogen-equivalent units in the baseline D-dimer level, and for every 50 percent decrease in the baseline fibrinogen level, respectively. The baseline platelet count and presence of intracranial hemorrhage were independently associated with death in a multivariate analysis.
“We did not find any individual risk factors for VITT, but we found increased mortality among patients who presented with severe thrombocytopenia, cerebral venous sinus thrombosis, intracranial hemorrhage, laboratory markers of severe coagulation activation, or all these variables,” the authors write.