Table 2

Studies of intensity of oral anticoagulation treatment in patients with antiphospholipid syndrome and previous venous thrombosis

ReferenceDesignComparisonPercentage with venous thrombosis historyInterventionControlNumber of patient-years, interventionNumber of patient-years, controlEvents, interventionEvents, controlRelative effect (95% CI)Study quality
Recurrent thrombosis
Crowther et al 200325RCTDirect100Warfarin INR 3–4Warfarin INR 2–3113 py119 py2.6/100 py0.8/100 pyHR 2.9 (0.3 to 28.0)Low risk of bias*
Finazzi et al 200526RCTIndirect68Warfarin INR 3–4.5Warfarin INR 2–3189 py181 py3.1/100 py1.6/100 pyHigh risk of bias*
Rosove and Brewer 199227Retrospective cohortIndirect56Warfarin INR 3–4Warfarin INR 2–3110.2 py40.9 py07/100 pyIntermediate quality
Khamashta et al 199528Retrospective cohortIndirect54Warfarin ≥INR 3.0Warfarin INR <3.0197.3 py141.3 py1.5/100 py23/100 pyHigh quality
Ames et al 200529Prospective cohortIndirect74Warfarin INR 3–4Warfarin INR 2–310.5/100 py4.0/100 pyIntermediate quality
TotalDirect and indirectRR 0.67 (0.05 to 8.20),
I2=82%
Major bleeding
Crowther et al 200325RCTDirect100Warfarin INR 3–4Warfarin INR 2–3111 py133 py2.7/100 py3.0/100 pyHR 1.0 (0.02 to 4.8)Low risk of bias*
Finazzi et al 200526RCTIndirect68Warfarin INR 3–4.5Warfarin INR 2–3189 py181 py1.0/100 py1.6/100 pyHigh risk of bias*
Khamashta et al 199528Retrospective cohortIndirect54Warfarin ≥3.0Warfarin <3.0197.3 py141.3 py1.7/100 py0High quality
Ames et al 200529Prospective cohortIndirect74Warfarin INR 3–4Warfarin INR 2–310.5/100 py0.57/100 pyIntermediate quality
Direct and IndirectRR 1.61 (0.34 to 7.56)
I2=35%
  • *Risk of bias for randomised controlled trials using the Cochrane tool.

  • INR, international normalised ratio; RCT, randomised controlled trial; py, person-years.