Session Title: Antiphospholipid Syndrome
Session Type: Abstract Submissions (ACR)
Background/Purpose: The so called “antiphospholipid score (aPL-S)” was recently developed and validated (1). This score was shown to be a useful quantitative index for diagnosing APS and to be valuable as a predictive marker for thrombosis in autoimmune diseases. We aimed to independently validate the aPL-S by applying the proposed score system to our cohort of SLE patients. (1. Otomo et al. Arthritis Rheum 2012; 64: 504)
Methods: we applied the aPL-S to a cohort of 211 consecutive SLE patients, all attending our Lupus Clinic. aPL-S was calculated for each patient by adding together the points corresponding to the risk factors as described. To validate the aPL-S, we adapted the proposed score using our in house cut-off values for aPL testing as previously reported or according to the current guidelines, as appropriate.
Results: Overall, 81 patients fulfilled criteria for APS and 73 patients had a history of thrombosis (48 arterial, 41 venous). Out of 144 women who had ever been pregnant, 61 had a history of pregnancy loss. Higher values of aPL-S were seen in patients who experienced thrombosis and/or pregnancy loss when compared to those without clinical events (median 17 [0-86] vs. 4 [0-31], p<0.001). When analysing clinical subgroups, patients who experienced thrombosis or pregnancy loss showed higher aPL-S compared to those without clinical events (median 18 [0-86] vs. 4 [0-27], p<0.001 for thrombosis; 7 [0-69] vs. 3 [0-29], p=0.029 for pregnancy loss). When the cut-off level for the aPL-S was defined as 30, as per the original study (1) the sensitivity and specificity of the aPL-S were 39% and 95%. The PPV of an aPL-S ≥30 was 36%, whereas the NPV was 91%.
Conclusion: We demonstrated that the aPL profile can be successfully quantified by the aPL-S in an independent cohort of SLE patients. The aPL-S correlated with a history of thrombosis and pregnancy loss in our cohort, suggesting that the aPL-S is a suitable quantitative marker for APS.
M. L. Bertolaccini,
M. A. Khamashta,
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/independent-validation-of-the-antiphospholipid-score-apl-s-for-the-diagnosis-of-antiphospholipid-syndrome-aps/