Rheumatology Advance Access originally published online on March 1, 2006
Rheumatology 2006 45(9):1116-1120; doi:10.1093/rheumatology/kel050
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The persistence of anticardiolipin antibodies is associated with an increased risk of the presence of lupus anticoagulant and anti-ß2-glycoprotein I antibodies
1Division of Clinical Epidemiology, 2Department of Hematology, Montreal General Hospital, McGill University Health Centre, 3Division of Rheumatology, Montreal General Hospital, Research Institute of the McGill University Health Centre, 4Department of Epidemiology and Biostatistics, McGill University, 5Laboratoire de Coagulation, Hôpital Maisonneuve-Rosemont, Université de Montréal, Montreal, Quebec, 6Division of Outcomes and Population Health, University Health Network Research Institute and 7Division of Rheumatology, University Health Network, University of Toronto, Toronto, Ontario, Canada.
Correspondence to: P. R. Fortin, Arthritis Centre of Excellence, Toronto Western Hospital, Room MP 10-304, 399 Bathurst Street, Toronto, Ontario, Canada M5T 2S8. E-mail: pfortin{at}uhnresearch.ca
Objective. We studied antiphospholipid antibodies (aPL) in blood samples from a cohort of individuals followed for thrombosis to determine whether the persistent presence of anticardiolipin antibodies (aCL) is associated with a greater likelihood of having lupus anticoagulant and/or anti-ß2-glycoprotein I antibodies (LA/aß2GPI).
Methods. Blood samples from 353 individuals who had been tested for aCL on at least two occasions were tested for aß2GPI and LA. Two groups were defined: aCL-persistent, who tested aCL-positive on at least two occasions, and aCL non-persistent, who tested aCL-positive on fewer than two occasions. Multivariate logistic regressions were performed using LA/aß2GPI, LA and aß2GPI as outcome variables and the percentage of aCL-positive tests as the predictor variable, adjusted for age, gender, family history of cardiovascular disease (CVD), systemic lupus erythematosus (SLE), smoking and number of venous (VT) and arterial thromboses (AT).
Results. Sixty-eight (19%) individuals were aCL persistent and 285 (81%) were aCL non-persistent. LA/aß2GPI was found in 36 (53%) of the aCL persistent group and 38 (13%) of the aCL non-persistent group. The two groups were similar for age, gender and smoking. Family history of CVD, SLE, VT and AT were more frequent in the aCL persistent group. Multivariate analyses revealed that odds ratios for LA/aß2GPI, LA and aß2GPI were 1.34 [95% confidence interval (CI)=1.22–1.47], 1.36 (95% CI=1.24–1.50) and 1.47 (95% CI=1.31–1.65) respectively for each 10% increase in aCL-positive tests vs 0% positive tests.
Conclusion. Persistence of aCL positivity is associated with an increased risk of LA/aß2GPI.
KEY WORDS: Antiphospholipid antibodies, Anticardiolipin antibodies, Lupus anticoagulant, Anti-ß2-glycoprotein I antibodies.