Non-OO blood type influences the risk of recurrent venous thromboembolism. A cohort study.
The role of ABO blood type as a risk factor for recurrent venous thromboembolism (VTE) in patients with a first unprovoked VTE who complete oral anticoagulation therapy is unknown. The aim of this study was to determine if non-OO blood type is a risk factor for recurrent VTE in patients with a first unprovoked VTE who completed 5-7 months of anticoagulant therapy. In an ongoing cohort study of patients with unprovoked VTE who discontinued oral anticoagulation after 5-7 months of therapy, six single nucleotide polymorphisms sites were tested to determine ABO blood type using banked DNA. The main outcome was objectively proven recurrent VTE. Mean follow-up for the cohort was 4.19 years (SD 2.16). During 1,553 patient-years of follow-up, 101 events occurred in 380 non-OO patients (6.5 events per 100 patient years; 95% CI 5.3-7.7) compared to 14 events during 560 patient years of follow-up in 129 OO patients (2.5 per 100 patient years; 95% CI 1.2-3.7), the adjusted hazard ratio was 1.98 (1.2-3.8). In conclusion, non-OO blood type is associated with a statistically significant and clinically relevant increased risk of recurrent VTE following discontinuation of anticoagulant therapy for a first episode of unprovoked VTE.
Dr. Marc Rodger, Division of Hematology, The Ottawa Hospital, General Campus, 501 Smyth Rd., Ottawa, ON K1H 8L6, Canada, Fax: +1 613 739 6102, E-mail: mrodger@ohri.ca.
Esteban
E
Gándara
Michael J
MJ
Kovacs
Susan R
SR
Kahn
Philip S
PS
Wells
David A
DA
Anderson
Isabelle
I
Chagnon
Grégoire
G
Le Gal
Susan
S
Solymoss
Mark
M
Crowther
Marc
M
Carrier
Nicole
N
Langlois
Judy
J
Kovacs
Julian
J
Little Ma
Nancy
N
Carson
Tim
T
Ramsay
Marc A
MA
Rodger
D000284:Administration, Oral; D000328:Adult; D000368:Aged; D000925:Anticoagulants / Q000008:administration & dosage*; D001789:Blood Group Antigens / Q000235:genetics / Q000378:metabolism*; D001788:Blood Grouping and Crossmatching; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D012008:Recurrence; D012307:Risk Factors; D054556:Venous Thromboembolism / Q000097:blood* / Q000188:drug therapy*; D028761:Withholding Treatment
D000925:Anticoagulants; D001789:Blood Group Antigens
Veins; blood cells; thrombosis