Background/Purpose

Recently, new scoring systems to quantify the probability for the diagnosis of antiphospholipid syndrome (APS) have been proposed in sequence: the Antiphospholipid Score(aPL-S) and the Global Antiphoshpholipid Syndrome Score (GAPSS). They are derived from the combinations of independent risks for thrombosis particularly focused on antiphospholipid antibodies profiles(aPL-S) or centered on the existence of each antiphospholipid antibodies taking into account with conventional cardiovascular disease risks (GAPSS). These scores, as well as tools for diagnosis, function as index for predicting future thrombosis in autoimmune diseases.

Methods

This study comprised 411 patients with autoimmune diseases who visited Hokkaido University Hospital Rheumatology Clinic between 2002 and 2003. Demographic, clinical data and cardiovascular risk factors were obtained from the medical charts. Lupus Anticoagulant (LAC) assays  and IgG/M anticardiolipin antibodies, IgG/M anti-β₂-glycoprotein I antibodies and IgG/M phosphatidylserine dependent antiprothrombin antibodies were performed in all subjects. Among all the patients, 257 (62.5%) patients with follow-up period of more than 5 years (median follow-up periods: 126(IQR 92.5,133) months) were eligible. The disease profile of these patients was as follows; 17(7%) primary APS, 25(10%) APS with systemic lupus erythematosus(SLE), 84(33%) SLE (without APS), 45(18%) rheumatoid arthritis and 85 patients with other autoimmune diseases.

 To evaluate the diagnostic powers for GAPSS and aPL-S, area under the curve (AUC) of receiver operating characteristic (ROC) curves were calculated. To evaluate the powers of the two scores for thrombosis prediction, Cox proportional hazard regression analyses were performed separately for each score with the cut off derived om the ROC curve. Each risk factor for the multivariate Cox analyses were assessed through separate univariate Cox regression test. To evaluate and compare the predictive powers of the two scores, Somer’s d coefficient was calculated.

Results

Thirty-seven patients newly developed thrombosis during the observation period; 23 arterial thrombosis and 23 venous thrombosis. The ROC curve of GAPSS showed higher AUC than that of aPL-S (0.693 vs 0.656, respectively, p<0.05) indicating that GAPSS has better ability of diagnosing APS (GAPSS vs aPL-s: 0.693 vs 0.656, p<0.05 ).The cut off values of GAPSS and aPL-S for predicting future thrombosis were 10 and 31, respectively. The Cox multivariate proportional hazard regression analyses revealed that both scores, with appropriate cut off levels,accurately reflected the risks of the future thrombosis with statistic significance(GAPSS>10 p=0.01, aPL-S>31 p<0.0001). The aPL-S showed higher Somer’s coefficient than GAPSS (0.497 vs 0.412, respectively, p<0.05)

Conclusion

The aPL-S and GAPSS accurately reflected the diagnosis of APS and the risk for future thrombotic events in patients with autoimmune diseases in our cohort. GAPSS may have relatively high potential for APS diagnosis and aPL-S might be superior to GAPSS in predicting future thrombosis.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/markers-of-thrombotic-events-in-autoimmune-diseasescomparison-of-antiphospholipid-score-apl-s-and-global-anti-phospholipid-syndrome-score-gapss/