Phenotype Algorithms for the Identification and Characterization of Vaccine-Induced Thrombotic Thrombocytopenia in Real World Data: A Multinational Network Cohort Study.

Azza Shoaibi ,Anthony G Sena ,Daniel Prieto‐Alhambra ,Thamir M Alshammari ,Peter R Rijneek ,Gowtham Rao ,Clement Fraboulet ,Tanguy Le Carrour ,Luis H John ,Daniel Moralès ,Anna Ostropolets ,Talita Duarte‐Salles ,Marc A Suchard ,Juan Manuel Ramírez-Anguita ,Spiros Denaxas ,Evan Minty ,Filip Maljković ,Clair Blacketer ,Scott Horban ,Frank Defalco ,Erica A Voss ,Biljana Carević ,Rupa Makadia ,Miguel Angel Mayer ,Václav Papež ,Patrick B Ryan

doi:10.1007/s40264-022-01187-y

Abstract

IntroductionVaccine-induced thrombotic thrombocytopenia (VITT) has been identified as a rare but serious adverse event associated with coronavirus disease 2019 (COVID-19) vaccines.ObjectivesIn this study, we explored the pre-pandemic co-occurrence of thrombosis with thrombocytopenia (TWT) using 17 observational health data sources across the world. We applied multiple TWT definitions, estimated the background rate of TWT, characterized TWT patients, and explored the makeup of thrombosis types among TWT patients.MethodsWe conducted an international network retrospective cohort study using electronic health records and insurance claims data, estimating background rates of TWT amongst persons observed from 2017 to 2019. Following the principles of existing VITT clinical definitions, TWT was defined as patients with a diagnosis of embolic or thrombotic arterial or venous events and a diagnosis or measurement of thrombocytopenia within 7 days. Six TWT phenotypes were considered, which varied in the approach taken in defining thrombosis and thrombocytopenia in real world data.ResultsOverall TWT incidence rates ranged from 1.62 to 150.65 per 100,000 person-years. Substantial heterogeneity exists across data sources and by age, sex, and alternative TWT phenotypes. TWT patients were likely to be men of older age with various comorbidities. Among the thrombosis types, arterial thrombotic events were the most common.ConclusionOur findings suggest that identifying VITT in observational data presents a substantial challenge, as implementing VITT case definitions based on the co-occurrence of TWT results in large and heterogeneous incidence rate and in a cohort of patints with baseline characteristics that are inconsistent with the VITT cases reported to date.Supplementary InformationThe online version contains supplementary material available at 10.1007/s40264-022-01187-y.

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