Results:

Among 294 patients who were evaluated, the authors identified 170 definite and 50 probable cases of VITT. All patients had received the first dose of ChAdOx1 nCoV-19 (AstraZeneca) vaccine between 5–48 days previously (median, 14 days). Age ranges were from 1–79 years (median, 48 years) with no sex preponderance and no identifiable medical risk factors. Overall mortality was 22% with odds of death that increased by 2.7 (95% confidence interval [CI], 1.4-5.2) among patients with cerebral venous sinus thrombosis. Odds of death increased by a factor of 1.7 (95% CI, 1.3-2.3) for every 50% decline in platelet count and by a factor of 1.2 (95% CI, 1.0-1.3) for every increase of 10,000 fibrinogen-equivalent units in the baseline D-dimer level. Finally, mortality odds were increased by a factor of 1.7 (95% CI, 1.1-2.5) for every 50% decrease in baseline fibrinogen level. Multivariable analysis identified that baseline platelet count and the presence of intracranial hemorrhage were independently associated with death. The observed mortality was 73% among patients with platelet counts below 30,000 per cubic millimeter and intracranial hemorrhage.