To examine the usefulness of a single measurement of anticardiolipin antibodies (aCL) in systemic lupus erythematosus (SLE) in routine clinical practice.All 127 patients with SLE currently followed by our rheumatology unit had an aCL measurement on routine clinic review. Their charts were then reviewed for specific disease manifestations. Basic statistical correlations of the aCL result and the specific disease manifestations were performed, and the clinical utility of the aCL test assessed using Bayesian analysis.aCL was positive (2 SD) in 24% and was associated with recurrent fetal loss, thrombosis, cerebrovascular disease, livedo reticularis and digital infarcts. Bayesian analysis showed that a single positive aCL test increased the relative and absolute risk of all the above complications. The criterion of aCL positivity as15 units (2 SD) was associated with the highest relative risk.A single positive aCL test in routine management of SLE is a useful predictor of important clinical events.
