Abstract
Introduction: The European Medicine Agency has authorized COVID-19 vaccination in adolescents and young
adults (AYAs) from 12 years onwards. In elderly vitamin K antagonist (VKA) users, COVID-19 vaccination has
been associated with an increased risk of supra- and subtherapeutic INRs. Whether this association is also
observed in AYAs using VKA is unknown. Our aim was to describe the stability of anticoagulation after COVID-19
vaccination in AYA VKA users.
Materials and methods: A case-crossover study was performed in a cohort of AYAs (12–30 years) using VKAs. The
most recent INR results before vaccination, the reference period, were compared with the most recent INR after
the first and, if applicable, second vaccination. Several sensitivity analyses were performed in which we
restricted our analysis to stable patients and patients without interacting events.
Results: 101 AYAs were included, with a median age [IQR] of 25 [7] years, of whom 51.5 % were male and 68.3
% used acenocoumarol. We observed a decrease of 20.8 % in INRs within range after the first vaccination, due to
an increase of 16.8 % in supratherapeutic INRs. These results were verified in our sensitivity analyses. No differences were observed after the second vaccination compared to before and after the first vaccination. Complications after vaccination occurred less often than before vaccination (9.0 vs 3.0 bleedings) and were nonsevere.
Conclusions: the stability of anticoagulation after COVID-19 vaccination was decreased in AYA VKA users.
However, the decrease might not be clinically relevant as no increase of complications nor significant dose
adjustments were observed.
adults (AYAs) from 12 years onwards. In elderly vitamin K antagonist (VKA) users, COVID-19 vaccination has
been associated with an increased risk of supra- and subtherapeutic INRs. Whether this association is also
observed in AYAs using VKA is unknown. Our aim was to describe the stability of anticoagulation after COVID-19
vaccination in AYA VKA users.
Materials and methods: A case-crossover study was performed in a cohort of AYAs (12–30 years) using VKAs. The
most recent INR results before vaccination, the reference period, were compared with the most recent INR after
the first and, if applicable, second vaccination. Several sensitivity analyses were performed in which we
restricted our analysis to stable patients and patients without interacting events.
Results: 101 AYAs were included, with a median age [IQR] of 25 [7] years, of whom 51.5 % were male and 68.3
% used acenocoumarol. We observed a decrease of 20.8 % in INRs within range after the first vaccination, due to
an increase of 16.8 % in supratherapeutic INRs. These results were verified in our sensitivity analyses. No differences were observed after the second vaccination compared to before and after the first vaccination. Complications after vaccination occurred less often than before vaccination (9.0 vs 3.0 bleedings) and were nonsevere.
Conclusions: the stability of anticoagulation after COVID-19 vaccination was decreased in AYA VKA users.
However, the decrease might not be clinically relevant as no increase of complications nor significant dose
adjustments were observed.
| Original language | English |
|---|---|
| Pages (from-to) | 121-127 |
| Number of pages | 7 |
| Journal | Thrombosis Research |
| Volume | 228 |
| DOIs | |
| Publication status | Published - 1 Aug 2023 |
Bibliographical note
Funding Information:The authors thank the federation of Dutch anticoagulation clinics for making the data available. This work was supported by the Netherlands Thrombosis Foundation [ 2020_A ] and the Netherlands Organization for Health Research and Development [project number 10430012010004 ]. The funding sources did not have involvement in the study design, the collection, analysis and interpretation of data, the writing of the report and in the decision to submit the article for publication.
Publisher Copyright:
© 2023
