title: Abnormally short activated partial thromboplastin time values are associated with increased risk of recurrence of venous thromboembolism after oral anticoagulation withdrawal.
abstract: This study prospectively evaluated the relationship between activated partial thromboplastin time (aPTT) and risk of venous thromboembolism (VTE) recurrence after oral anticoagulant (OA) withdrawal in patients with a previous unprovoked VTE event. Six hundred twenty-eight patients (331 males; median age: 67 years) were followed after OA interruption (mean follow-up = 22 months). Three to four weeks from OA discontinuation patients were given a complete thrombophilic work-out, including aPTT (automated aPTT). Recurrent symptomatic VTE events (objectively documented) occurred in 71/628 (11.3%, 6.8/100 person-years) patients. The VTE recurrence rate was 17.5% and 7.5% in patients with aPTT in the lower (ratio < or =0.90) and in the upper (ratio >1.05) quartiles. The recurrence risk was more than twofold higher in patients with ratio < or =0.90 versus those of the reference category [Relative risk (RR): 2.38 (95% confidence interval (CI): 1.18-4.78)]. As expected, the increase in recurrence risk disappeared after adjustment for factor VIII, IX and XI levels [RR: 1.74 (95%CI: 0.43-2.76)]. In contrast, the risk was persistently increased in patients with a ratio < or =0.90 [RR: 2.07 (95%CI: 1.02-4.18)] after adjustment for age, gender and d-dimer level. The aPTT predictive value was independent of the presence of inherited thrombophilic alterations. In conclusion, abnormally short aPTT values are associated with a significantly increased risk of VTE recurrence.
authors.affiliation: Department of Angiology and Blood Coagulation 'Marino Golinelli', University Hospital S. Orsola-Malpighi, Bologna, Italy. legnani@aosp.bo.it
authors.forename: Cristina
authors.initials: C
authors.lastname: Legnani
authors.forename: Silvia
authors.initials: S
authors.lastname: Mattarozzi
authors.forename: Michela
authors.initials: M
authors.lastname: Cini
authors.forename: Benilde
authors.initials: B
authors.lastname: Cosmi
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Favaretto
authors.forename: Gualtiero
authors.initials: G
authors.lastname: Palareti
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000008:administration & dosage*; D004812:Epidemiologic Methods; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D008297:Male; D008875:Middle Aged; D010314:Partial Thromboplastin Time; D011655:Pulmonary Embolism / Q000097:blood* / Q000188:drug therapy; D012008:Recurrence; D019851:Thrombophilia / Q000097:blood / Q000188:drug therapy / Q000235:genetics; D020246:Venous Thrombosis / Q000097:blood* / Q000188:drug therapy
chemical_list: D000925:Anticoagulants