Characteristics of Chinese patients with antiphospholipid syndrome and the ability of lupus anticoagulant assays to identify them.

BACKGROUND: The objective of the work was to study the manifestations of antiphospholipid syndrome (APS) in the Chinese population, and evaluate the ability of lupus anticoagulant (LAC) assays to identify APS.

METHODS: Consecutive patients with APS from 2012 to 2015 in our hospital were recruited, strictly following the Sydney revised Sapporo criteria for APS classification. Meanwhile, in the LAC-positive population, LAC normalized ratios obtained from diluted Russell viper venom time (DRVVT) and silica clotting time (SCT) assays were compared between patients with and without APS.

RESULTS: One hundred and seventeen patients with defined APS comprised 86 women and 31 men with a mean age of 38 years (range 9-78 years), 38 (32.5%) of them had systemic lupus erythematosus. The prevalence of arterial thrombosis, venous thrombosis and obstetric complications were 46.2%, 25.6% and 30.8%, respectively. LAC was detected in 105 patients (89.7%), anti-β2-glycoprotein I antibodies (aβ2GPI) in 88 (75.2%) and anticardiolipin antibodies in 41 (35.0%). In 353 patients with persistent LAC, the receiver operator characteristic (ROC) curve for APS prediction defined the best cut-off value for DRVVT normalized ratio as 1.61 with 73.7% specificity and 72.6% sensitivity. For SCT, the normalized ratio was 1.91 with 70.8% specificity and 56.5% sensitivity.

CONCLUSIONS: A high prevalence of arterial thrombosis and LAC-positive result was noted in Chinese patients with APS, and an appropriate threshold for LAC normalized ratios could help to discriminate APS from non-APS patients in the LAC-positive population.