Acute management of suspected vaccine induced thrombocytopenia and thrombosis

Sarah Dalrymple; Sunil Patel; Clementine Fraser; Rachel Tennant

doi:10.7861/clinmed.22-4-s52

Introduction

In 2021 vaccine induced thrombocytopenia and thrombosis (VITT) emerged as an adverse event following COVID-19 vaccination. VITT is rare; nevertheless, it can lead to catastrophic thrombosis and secondary haemorrhage with high mortality.¹ Studies show that patients with VITT have thrombocytopenia at presentation and subsequent coagulation abnormalities on available assays.² At our district general hospital (DGH), patients with suspected VITT but normal platelet counts were found to have had further VITT investigations such as D-dimer, fibrinogen and in some cases, neuroimaging. Unnecessary diagnostic tests have a significant financial burden on healthcare.

Methods

We conducted a retrospective analysis of adult patients (>18 years old) presenting to the emergency department (ED) with acute headache following administration of at least one COVID-19 vaccination. We audited against standards published by the Royal College of Physicians and Royal College of Emergency medicine on management of suspected VITT in April 2021 and then re-audited against updated guidance published in May 2021 to close the loop.³

The audit period included patients presenting to the emergency department (ED) between 1 February 2021 and 31 August 2021. An anonymised electronic reporting form was developed to capture the following data: triage presentation, discharge destination, brand of vaccine, days since vaccination, platelet count, D-dimer, fibrinogen and neuroimaging.

Results

176 patients were included in the audit. 36 patients presented before formal guidance was issued. Seventy-two patients were included in audit cycle 1 and 68 patients were included in cycle 2. There was one case of VITT in a patient with thrombocytopenia. The median day of presentation to ED post vaccine dose was 7 days in cycle 1 and double that (14 days) in cycle 2. 67% of patients presented in the window for suspected VITT in the first cycle and 81% presented during the updated interval post-vaccine in cycle 2. In cycle 1, 2.8% of patients were thrombocytopenic; nevertheless, 37% and 31% of patients had a D-Dimer and fibrinogen sent respectively. In cycle 2 no patients were thrombocytopenic; nevertheless, 32% had a D-Dimer sent and 16% had a fibrinogen assay added. 25% of patients in cycle 1 had neuroimaging done with a normal platelet count and this increased to 40% in cycle 2.

Conclusion

VITT is a new occurrence following the roll-out of the COVID-19 vaccination program and guidance was only established in April 2021. Our data demonstrated that there were no cases of VITT with a platelet count of >150 × 10⁹/L. Our data suggest we can be confident in the parameters set in national guidance. Our data also reflects current literature demonstrating that VITT is rare; nevertheless, when associated with significant clotting, abnormalities can be fatal.²

This audit shows that in the investigation of VITT at our DGH, that while the triaging of patients to a suspected diagnosis is high there is a poor adherence to subsequent laboratory and radiological guidance. Reasons for this are multifactorial. Nevertheless, requesting unnecessary blood tests and neuroimaging has financial implications.

References

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1. Pavord S
, Hunt B, Horner D, Bewley S, Karpusheff J. Vaccine induced immune thrombocytopenia and thrombosis: summary of NICE guidance. BMJ 2021;375:n2195.
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1. Pavord S
, Scully M, Hunt B, et al. Clinical features of vaccine-induced immune thrombocytopenia and thrombosis. New Engl J Med 2021;385:1680–9.
OpenUrl PubMed
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1. Royal College of Emergency Medicine
. Management of patients presenting to the emergency department/acute medicine with symptoms of Covid-19 vaccine induced thrombosis and thrombocytopenia (VITT). RCEM, 2021.