Table 2 Recurrent thrombosis in patients with antiphospholipid antibodies and duration of anticoagulation treatment

Retrospective

70 pt with aPL + arterial/venous thrombosis (1^st event)

5.2 years

Recurrence rates (per patient year):

▪ 0.19 for no treatment, 0.32 for aspirin, 0.57 for warfarin INR = 1.9, 0.07 for warfarin 2.0 = INR = 2.9 (p = 0.12)

▪ 0.00 for warfarin INR = 3.0 (p < 0.001)

Rosove MH et al. Ann Intern Med 1992

Retrospective

19 pt with aPL + venous thrombosis (1^st event)

8 years

Probability of survival free from venous thrombosis (Kaplan Meyer method):

▪ 100% in patients kept on warfarin vs. 22% in patients in whom warfarin was stopped – log rank test p = 0.000007

Derksen R et al. Ann Rheum Dis 1993

Retrospective

147 pt with aPL + arterial/venous thrombosis (1^st event)

7 years

Recurrence rates (events per year):

▪ 0.29 for no treatment

▪ 0.015 for INR > 3, 0 for INR > 3 + aspirin (p < 0.001)

Probability of survival free from thrombosis (Kaplan Meyer method):

▪ 90% in patients kept on warfarin INR > 3 + aspirin vs. 30% in patients on no treatment (5 years)

Khamashta M et al. N Eng J Med 1995

Prospective

211 pt with a 1^st recurrent venous thrombosis

4 years

Recurrence rates:

▪ 3/15 pt aCL+ (20%) and 20/90 pt aCL- (22%) allocated 6 months warfarin

▪ 1/19 pt aCL+ (5%) and 2/87 pt aCL- (2%) allocated indefinite warfarin therapy

Schulman S et al. Am J Med 1998

Prospective

162 pt with venous thrombosis (1^st idiopathic event) having completed 3 months of warfarin, allocated to either placebo or further 24 months warfarin

10 months

Total of 8 aPL +/150 pt tested (aPL prevalence 5%)

Recurrence rates:

▪ 4/6 aPL pt that completed only 3 months warfarin (placebo group) – HR (95%CI) of 4 when compared to patients without aPL.

All patients 162; placebo group 83; warfarin group 79

Kearon C et al. N Eng J Med 1999