title: The risk of recurrent venous thromboembolism among patients with high factor IX levels.
abstract: High factor IX (FIX) is a risk factor of deep vein thrombosis. The impact of high FIX on the risk of recurrent venous thrombosis is unknown. We prospectively followed 546 patients after anticoagulation for a first spontaneous venous thromboembolism. Patients with a natural coagulation inhibitor deficiency, lupus anticoagulant or cancer were excluded. At 3 years, the likelihood of recurrence was 23% among patients with high FIX (exceeding the 75th percentile) compared with 11% among patients with lower levels. Among patients with high FIX, the relative risk of recurrence was 2.2 (95% CI: 1.3-3.6) before and was 1.6 (95% CI: 1.0-2.8) after adjustment for age, gender, duration of anticoagulation, FV Leiden, FII G20210A, high FVIII and hyperhomocysteinemia. Compared with patients with low factor IX (< 138 IU dL(-1)) and low FVIII (</= 234 IU dL(-1)), the relative risk of recurrence was 1.5 among patients with high FIX and low FVIII, 2.7 among patients with low FIX and high FVIII and 6.6 among patients with high FIX and high FVIII. High levels of FIX confer an increased risk of recurrent venous thromboembolism and enhance the risk of recurrence among patients with high FVIII.
authors.affiliation: Department of Internal Medicine I, Division of Hematology and Hemostasis, Vienna University Hospital, Vienna, Austria.
authors.forename: A
authors.initials: A
authors.lastname: Weltermann
authors.forename: S
authors.initials: S
authors.lastname: Eichinger
authors.forename: C
authors.initials: C
authors.lastname: Bialonczyk
authors.forename: E
authors.initials: E
authors.lastname: Minar
authors.forename: M
authors.initials: M
authors.lastname: Hirschl
authors.forename: P
authors.initials: P
authors.lastname: Quehenberger
authors.forename: V
authors.initials: V
authors.lastname: Schönauer
authors.forename: P A
authors.initials: PA
authors.lastname: Kyrle
mesh_terms: D000328:Adult; D000368:Aged; D000925:Anticoagulants / Q000627:therapeutic use; D005164:Factor IX / Q000032:analysis*; D005169:Factor VIII / Q000032:analysis; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012008:Recurrence; D012307:Risk Factors; D013923:Thromboembolism / Q000097:blood*; D020246:Venous Thrombosis / Q000097:blood*
chemical_list: D000925:Anticoagulants; D005169:Factor VIII; D005164:Factor IX