The autoimmune condition antiphospholipid syndrome mainly affects young women. An Article published Online First and in the November edition of The Lancet Neurology shows that women with a particular subtype of antibody called lupus anticoagulant (LA) have a more than 40-fold increased risk of stroke and 5-fold increased risk of heart attack compared with the general population (of young women). Smoking and oral contraceptive use increase the risk of these events even more. The Article is written by Dr Rolf Urbanus and Dr Philip de Groot, University Medical Centre Utrecht, Netherlands, together with colleagues from the Leiden University Medical Centre.
Antiphospholipid syndrome occurs when autoantibodies* bind to cell membranes, interfering with the regular clotting mechanism of the blood. Diagnosis occurs when young women (under 50 years) suffer a thrombotic event such as a stroke or heart attack, and antiphospholipid antibodies are tested. Although it is known that this condition causes thrombosis, bleeding, and repeat miscarriage in women, the extent of the increased risk for stroke and heart attack was unknown before this study.
The authors used data from the RATIO study (Risk of Arterial Thrombosis In relation to Oral contraceptives) for their analysis. A total of 1,006 women aged under 50 years were enrolled between 1990 and 2001. Questionnaires were used to assess the prevalence of various risk factors, with blood samples taken to measure various phospholipid antibodies, including LA. The patient pool included women who had had a stroke (175), or heart attack (203), and healthy controls (628).
LA was found in 30 (17%) patients with stroke, 6 (3%) patients with heart attack, and four (0.7%) healthy controls. Based on the observation that 4 of 628 healthy controls had LA, the prevalence in women in the general population is estimated by the authors to be 7 in 1000, or 0.7%; previous studies have made higher estimates. LA increased the risk of stroke 43-fold compared with healthy controls; in women with LA who smoked, the risk was raised 87-fold; and in women with LA who used oral contraceptives, the risk was increased more than 200-fold. LA also increased with risk of heart attack 5-fold compared with healthy controls; LA plus smoking increased the risk 34-fold, and LA plus oral contraceptives increased the risk 22-fold. Smoking and oral contraceptive use enhance the action of LA, explaining these increased risks.
The authors say: “Our results suggest that lupus anticoagulant is a major risk factor for arterial thrombotic events in young women, and the presence of other cardiovascular risk factors increases this risk even further…Screening for lupus anticoagulant in young women with ischaemic stroke seems to be warranted.”
In an accompanying Reflection and Reaction, Dr Kathryn Kirchoff-Torres and Dr Steven R Levine, Stroke Center, Mount Sinai School of Medicine, New York, NY, USA, say that the most important aspect of the study is its conclusion that young women with LA need to be warned about the dangers of smoking and use of oral contraceptives.
The Lancet Neurology