RT Journal Article
SR Electronic
T1 Identifying unprovoked thromboembolism patients at low risk for recurrence who can discontinue anticoagulant therapy
JF Canadian Medical Association Journal
JO CMAJ
FD Canadian Medical Association
SP 417
OP 426
DO 10.1503/cmaj.080493
VO 179
IS 5
A1 Marc A. Rodger, MD MSc
A1 Susan R. Kahn, MD MSc
A1 Philip S. Wells, MD MSc
A1 David A. Anderson MD
A1 Isabelle Chagnon MD
A1 Grégoire Le Gal, MD PhD
A1 Susan Solymoss MD
A1 Mark Crowther MD
A1 Arnaud Perrier MD
A1 Richard White MD
A1 Linda Vickars MD
A1 Tim Ramsay, PhD MSc
A1 Marisol T. Betancourt, MD MSc
A1 Michael J. Kovacs MD
YR 2008
UL http://www.cmaj.ca/content/179/5/417.abstract
AB Background: Whether to continue oral anticoagulant therapy beyond 6 months after an “unprovoked” venous thromboembolism is controversial. We sought to determine clinical predictors to identify patients who are at low risk of recurrent venous thromboembolism who could safely discontinue oral anticoagulants. Methods: In a multicentre prospective cohort study, 646 participants with a first, unprovoked major venous thromboembolism were enrolled over a 4-year period. Of these, 600 participants completed a mean 18-month follow-up in September 2006. We collected data for 69 potential predictors of recurrent venous thromboembolism while patients were taking oral anticoagulation therapy (5–7 months after initiation). During follow-up after discontinuing oral anticoagulation therapy, all episodes of suspected recurrent venous thromboembolism were independently adjudicated. We performed a multivariable analysis of predictor variables (p < 0.10) with high interobserver reliability to derive a clinical decision rule. Results: We identified 91 confirmed episodes of recurrent venous thromboembolism during follow-up after discontinuing oral anticoagulation therapy (annual risk 9.3%, 95% CI 7.7%–11.3%). Men had a 13.7% (95% CI 10.8%–17.0%) annual risk. There was no combination of clinical predictors that satisfied our criteria for identifying a low-risk subgroup of men. Fifty-two percent of women had 0 or 1 of the following characteristics: hyperpigmentation, edema or redness of either leg; D-dimer ≥ 250 μg/L while taking warfarin; body mass index ≥ 30 kg/m2; or age ≥ 65 years. These women had an annual risk of 1.6% (95% CI 0.3%–4.6%). Women who had 2 or more of these findings had an annual risk of 14.1% (95% CI 10.9%–17.3%). Interpretation: Women with 0 or 1 risk factor may safely discontinue oral anticoagulant therapy after 6 months of therapy following a first unprovoked venous thromboembolism. This criterion does not apply to men. (http://Clinicaltrials.gov trial register number NCT00261014)