Arthritis & Rheumatism, Volume 60,
October 2009 Abstract Supplement

The 2009 ACR/ARHP Annual Scientific Meeting
Philadelphia October 16-21, 2009.


Antiphospholipid Score (aPL-S) in the Antiphospholipid Syndrome: Diagnostic Significance and Predictive Value for the Development of Thrombotic Events in Autoimmune Diseases

Otomo,  Kotaro, Atsumi,  Tatsuya, Fujieda,  Yuichiro, Kato,  Masaru, Miyamoto,  Eriko, Oku,  Kenji, Amengual,  Olga

Purpose:

1) To define the Antiphospholipid Score (aPL-S) by testing multiple antiphospholipid antibodies, and 2) to evaluate its efficacy for the diagnosis of antiphospholipid syndrome (APS) and predictive value for the development of thrombotic events in autoimmune diseases

Method:

1) From our database of autoimmune disease clinic, the results of antiphospholipid antibodies in 233 patients were used to define aPL-S. Five clotting assays (the mixing studies: activated partial thromboplastin time (APTT), kaolin clotting time, the dilute Russel's viper venom test (dRVVT), and the confirmatory tests: APTT and dRVVT) and 6 ELISAs (IgG/M anticardiolipin antibodies, IgG/M anti-beta2-glycoprotein I antibodies and IgG/M phosphatidylserine dependent antiprothrombin antibodies) were analyzed. The aPL-S was calculated according to the number of positive tests and their titers (range 0–83), and compared with the history of thrombosis/pregnancy morbidity. 2) For further analysis, we retrospectively explored the predictive value of aPL-S for thrombotic events. This part of the study comprised 221 patients with autoimmune diseases (12 primary APS, 16 APS with systemic lupus erythematosus and 193 other autoimmune diseases). The aPL-S in 2002 was evaluated in all subjects. Among all the patients, 174 (78%) were followed-up with a mean duration of 66 ±16 months. To calculate the predictive value, the aPL-S was compared with the development of thrombotic events during the follow-up period.

Results:

1) The aPL-S was higher in patients with thrombosis/pregnancy morbidity (n=46) than in those without (22.3±26.3 vs. 4.13±10.8, p=0.00001). For the diagnosis of APS, the receiver operating characteristics (ROC) curve of aPL-S showed hyperbolic, and the area under the ROC curve (ROC AUC) are 0.752 and 0.686 for the aPL-S and for the Sydney revised Sapporo criteria, respectively. The prevalence of thrombosis/pregnancy morbidity was correlated with the levels of aPL-S (Figure). 2) Seventeen patients newly developed thromboses; 10 arterial and 10 venous thromboses. Although 18 out of 19 patients with aPL-S >30 received antithrombotic therapy (4 anticoagulant therapies, 14 antiplatelet therapies and 2 both therapies), six of them developed 8 thrombotic events during the follow-up. Patients with aPL-S >30 had a higher risk of thrombosis than those without (Odds-Ratio: 6.04[95%CI: 1.92–18.99, p=0.004]).

Figure. The bar charts indicate the percentages of the prevalence of APS manifestations in each groups of aPL-S. The values inside the bar indicate the number of the patients.

Conclusion:

The aPL-S is a useful quantitative index for diagnosing APS, and may be a predictive marker of thrombosis in autoimmune diseases.

To cite this abstract, please use the following information:
Otomo, Kotaro, Atsumi, Tatsuya, Fujieda, Yuichiro, Kato, Masaru, Miyamoto, Eriko, Oku, Kenji, et al; Antiphospholipid Score (aPL-S) in the Antiphospholipid Syndrome: Diagnostic Significance and Predictive Value for the Development of Thrombotic Events in Autoimmune Diseases [abstract]. Arthritis Rheum 2009;60 Suppl 10 :1216
DOI: 10.1002/art.26290

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