Abstract
It is well known that the ABO blood group exerts a major influence on hemostasis,
as O blood group individuals have lower von Willebrand factor and factor VIII levels
than non-O blood group subjects. To evaluate the possible clinical implication of
the different ABO blood groups on the risk of developing venous thromboembolism (VTE),
we conducted a meta-analysis of the existing literature. After an electronic search
strategy using Medline and Embase and a manual review of abstract books of the International
Society on Thrombosis and Haemostasis and of reference lists of all retrieved articles,
we included in the systematic review 38 studies with 10,305 VTE cases. The prevalence
of non-O blood group was significantly higher in VTE patients compared with controls
with a resulting pooled odds ratio (OR) of 2.09 (95% confidence interval [CI], 1.83,
2.38; p < 0.00001). Similar findings were obtained when the genotypes A1O/BO/A2B (OR 1.73, 95% CI, 1.47, 2.05; p < 0.00001) and A1B/A1A1/BB (OR 1.87, 95% CI, 1.84, 2.44; p < 0.00001) were analyzed. The maximum VTE risk was observed in non-O–factor V Leiden
patients (OR 7.60, 95% CI, 3.21, 17.99), while for G20210A prothrombin mutation it
was not possible to perform a pooled analysis due to a paucity of published studies.
Finally, the association between non-O blood group and VTE was weaker when provoked
VTE cases were considered (OR 1.33, 95% CI, 1.18, 1.50), while it was substantially
unchanged when unprovoked VTE cases were analyzed (OR 1.88, 95% CI, 1.42, 2.50). In
conclusion, considering its prevalence, non-O blood group is a candidate to be one
of the most important genetic risk factors for venous thrombosis.
Keywords
ABO blood group - von Willebrand factor - factor VIII - venous thromboembolism