Table 2.
Recurrent thrombosis in patients with antiphospholipid antibodies and duration of anticoagulation treatment
| Study design | N | Mean follow up | Results | Reference |
| Retrospective | 70 pt with aPL + arterial/venous thrombosis (1st 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 (1st 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 (1st 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 1st 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 (1st 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 |
aPL – antiphospholipid antibodies; aCL – anticardiolipin antibodies; CI – confidence interval; HR – hazard ratio; INR – international normalized ratio; pt – patients