Abstract Number: LPB0142
Meeting: ISTH 2021 Congress
Background: Several studies report the association between non-O blood group and the risk to develop a venous thromboembolic event (VTE). Nevertheless, the role of non-O blood type and its interactions with inherited thrombophilia (i.e. antithrombin, protein S and C deficiencies, factor V Leiden and prothrombin variant) as possible risk factors for venous thrombosis in women undergoing oral contraceptive therapy (OCT) remain unclear.
Aims: We aimed to retrospectively evaluate the prevalence of non-O blood type and inherited thrombophilia in a large group of women with a venous thromboembolic event due to OCT.
Methods: A group of n.223 women with a personal history of venous thrombosis and/or pulmonary embolism due to OCT assumption, referred to the Medical Department of Padova University Hospital between December 2009 and December 2019, were enrolled. Women under 18 yrs and those with acquired thrombophilia were excluded. Two hundred and twenty-three healthy women underwent OCT for at least six months acted as controls. The Odds Ratios (ORs) and 95% confidence intervals (CIs) were calculated as an estimate of VTE developing.
Results: Out of n. 223 enrolled women, n. 168 (75%) had non-O blood group. The prevalence of non-O blood group was significantly higher in cases than controls (p <0.001). Inherited thrombophilia was observed in n. 86 (39%) patients. The prevalence of thrombophilia was significantly associated with the risk to develop OCT related VTE (p <0.01 respectively). Moreover, the combination of non-O blood type and inherited thrombophilia was associated with a 4.4-fold (CI 95% 1.98-9.78) increased risk to develop OCT related VTE.
Conclusions: Either non-O blood group or inherited thrombophilia are associated with an increased risk to develop OCT related VTE. The combination of these two conditions further increase this thrombotic risk. Larger studies are needed to confirm our results and to clarify the possible clinical meaning of our findings.
To cite this abstract in AMA style:Poretto A, Spiezia L, Turatti G, Marobin M, Borella E, Campello E, Tormene D, Simioni P. Association between Non-O Blood Group and the Risk of Venous Thromboembolism due to Oral Contraceptive Therapy [abstract]. Res Pract Thromb Haemost. 2021; 5 (Suppl 1). https://abstracts.isth.org/abstract/association-between-non-o-blood-group-and-the-risk-of-venous-thromboembolism-due-to-oral-contraceptive-therapy/. Accessed September 24, 2021.
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