Deep vein thrombosis: 6 weeks of anticoagulation was not clearly as safe as 12 weeks for a calf DVT

Clinical bottom line (level 1b-)

  1. Patients with a first calf DVT who received anticoagulation for 6 weeks compared with 12 weeks were not clearly more likely to have a recurrent venous thromboembolism nor less likely to have a major bleed.
  2. Patients with a first proximal DVT or pulmonary embolism who received 12 weeks of anticoagulation compared with 24 weeks were not clearly more likely to have a recurrent venous thromboembolism nor less likely to have a major bleed.
Pinede et al: Circulation 2001; 103 : 2453-2460
Expires May 2004

The study

Double-blinded ?concealed randomised trial with intention-to-treat
Setting: 8 anticoagulation clinics, France

736 patients (aged , % male) with a first calf or proximal deep vein thrombosis or pulmonary embolism (confirmed on objective testing)

Excluded if
  • aged < 18
  • severe PE or PE treated by thrombolysis
  • disease requiring prolonged anticoagulation
  • liver insufficiency
  • pregnancy or breast-feeding
  • previous venous thromboembolism
  • vena caval filter implantation or surgical thrombectomy
  • free-floating thrombus in inferior vena cava lumen
  • malignancy
  • known thrombophilia

Control Group: (n = 375, 375 analysed): calf DVT: anticoagulation for 6 weeks; proximal DVT or PE: anticoagulation for 12 weeks
Experimental Group: (n = 361, 361 analysed): calf DVT: anticoagulation for 12 weeks; proximal DVT or PE: anticoagulation for 24 weeks
All patients received heparin for at least 5 days, followed by oral fluindione adjusted so INR 2.0 to 3.0.
97% followed for 15 months
Outcome notes:
  • major bleeding : requiring hospitalisation, tranfusion or treatment with blood products or vitamin K; intracranila, intraocular, intraarticular or retroperitoneal, and/or when Hb fell by 2 g/dl or more.

The evidence

calf DVT: 6 weeks v. 12 weeks
Outcome Time to outcome CER EER RRR
(95% CI)		 ARR
(95% CI)		 NNT
(95% CI)
recurrent venous thromboembolism 15 months 2
(1.90%)		 3
(3.26%)		 -71%
(-902% to 71%)		 -1.36%
(-5.83% to 3.12%)		 -74
(NNT = 32 to infinity;
NNH = 17 to infinity)
major bleeding 15 months 13
(12.4%)		 19
(20.7%)		 -67%
(-2220% to 13%)		 -8.27%
(-18.7% to 2.13%)		 -12
(NNT = 47 to infinity;
NNH = 5 to infinity)

proximal DVT or PE: 12 weeks v. 24 weeks
Outcome Time to outcome CER EER RRR
(95% CI)		 ARR
(95% CI)		 NNT
(95% CI)
recurrent venous thromboembolism 15 months 21
(7.78%)		 23
(8.55%)		 -10%
(-94% to 38%)		 -0.77%
(-5.40% to 3.85%)		 -130
(NNT = 26 to infinity;
NNH = 19 to infinity)
major bleeding 15 months 43
(15.9%)		 46
(17.1%)		 -7%
(-57% to 27%)		 -1.17%
(-7.44% to 5.09%)		 -85
(NNT = 20 to infinity;
NNH = 13 to infinity)

Comments

  1. Patients were randomised in blocks of four.

Citation

  1. Pinede L, Ninet J, Duhaut P, et al: comparison of 3 and 6 months of oral anticoagulant therapy after a first episode of proximal deep vein thrombosis or pulmonary embolism and comparison of 6 and 12 weeks of therapy after isolated calf deep vein thrombosis. Circulation 2001; 103 : 2453-2460
Search Terms: from ACP Journal Club
Contributor: Chris Ball, May 2002
Reviewer:

Clinical Question.
Patient deep vein thrombosis
Intervention or Exposure anticoagulation duration
Outcome recurrent venous thromboembolism, major bleeding