How to manage patients with systemic lupus erythematosus who are also antiphospholipid antibody positive

Between 20% and 40% of patients with systemic lupus erythematosus (SLE) have positive blood tests for antiphospholipid antibodies (aPLs). This article explains what tests are used to detect these antibodies and outlines the complexities of interpreting and acting upon a positive result. If aPLs are persistently positive, the patient may develop antiphospholipid syndrome (APS) characterised by vascular thrombosis, pregnancy morbidity or both. In patients with SLE who are aPL-positive but have not developed APS, there is some evidence that low-dose aspirin should be used prophylactically, but it is not conclusive. APS in patients with SLE is clinically similar to primary APS and should be treated in the same way, with anticoagulation to prevent recurrent thrombosis or with aspirin and sometimes heparin to prevent pregnancy loss. Current best practice in use of these treatments is discussed. However, these treatments are not ideal as they can have major side effects such as haemorrhage. Research which may lead to better, more targeted therapy for APS is discussed at the end of the article.