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Abnormally short activated partial thromboplastin time values are associated with increased risk of recurrence of venous thromboembolism after oral anticoagulation withdrawal
Author(s) -
Legnani Cristina,
Mattarozzi Silvia,
Cini Michela,
Cosmi Benilde,
Favaretto Elisabetta,
Palareti Gualtiero
Publication year - 2006
Publication title -
british journal of haematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.907
H-Index - 186
eISSN - 1365-2141
pISSN - 0007-1048
DOI - 10.1111/j.1365-2141.2006.06130.x
Subject(s) - medicine , partial thromboplastin time , discontinuation , relative risk , confidence interval , quartile , risk factor , gastroenterology , lower risk , hazard ratio , surgery , coagulation
Summary 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 ≤0·90) and in the upper (ratio >1·05) quartiles. The recurrence risk was more than twofold higher in patients with ratio ≤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 ≤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.