Prevalence and isotype distribution of antiphospholipid antibodies in unselected Chilean patients with venous and arterial thrombosis.

Antiphospholipid antibodies (aPL) are a heterogeneous family of antibodies associated with thrombotic events and other complications. The objective of this study was to investigate the prevalence of aPL in a group of Chilean patients with thrombosis. Two hundred and twenty-six patients with venous and arterial thrombosis and 95 healthy controls were studied. Anticardiolipin (aCL), anti-beta(2 )glycoprotein I (anti-beta(2)GPI), and antiprothrombin (aPT) antibodies were determined. Eighty-eight out of 226 (38.9%) patients with thrombosis had some type of aPL. Fifty-seven patients (25.2%) were positive for aCL, 31 (13.7%) for aPT, and 14 (6.2%) for anti-beta(2)GPI antibodies. Twelve patients (5.3%) were positive for more than one aPL. IgG, IgM and IgA isotypes were observed in aCL, anti-beta(2)GPI, and aPT antibodies. Twenty-six out of 92 (28.3%) patients with venous thrombosis and 31/134 (23.1%) patients with arterial thrombosis were positive for aCL antibodies. With regard to the control group (4/95=4.2%), the odd ratios (OR) were 5.2 (1.3-19.8; p0.01) and 5.7 (1.6-22.3; p0.01), respectively. Additionally, we observed statistically significant OR with aPT and anti-beta(2)GPI antibodies; in the first, with venous and arterial thrombosis, and in the second, only with arterial thrombosis. Our results show a significant prevalence of aPL, predominantly aCL and aPT antibodies, in patients with thrombosis. Additionally, aCL and aPT antibodies appear to be a risk factor for venous and arterial thrombosis, and anti-beta(2)GPI antibodies appear to be a risk factor for arterial thrombosis.