Determination of Risk Factors
Hypertension was defined as the use of any antihypertensive medication or blood pressure higher than 140/90 mmHg on more than two occasions during the follow-up period. Diabetes mellitus was defined as the use of any antidiabetic medication or haemoglobin A1c (NGSP) > 6.5%. Dyslipidaemia was defined as the use of any lipid-lowering agents or an elevated serum low-density lipoprotein concentration > 140 mg/dl. Glucocorticosteroid treatment was defined as the use of any oral or intravenous corticosteroid therapy for more than three consecutive months at any time of the follow-up. Current cigarette smoking was defined as any cigarette or cigar during the follow-up period.
Determination of Antiphospholipid Antibodies and the Antiphospholipid Score (aPL-S)
For lupus anticoagulant (LA), mixing tests of three clotting assays were performed using a semiautomated hemostasis analyzer (STart 4; Diagnostica Stago) according to the guidelines recommended by the Subcommittee on Lupus Anticoagulant/Antiphospholipid Antibody of the Scientific and Standardization Committee of the International Society on Thrombosis and Haemostasis . For measurement of the activated Partial Thromboplastin Time (APTT), PTT-LA test (Diagnostica Stago) was used for screening and confirmed with mixing test using Staclot LA kit (Diagnostica Stago). The Dilute Russell's viper venom time (dRVVT) was screened and confirmed by the Gradipore LA test (Sydney New South Wales, Australia) and the kaolin clotting time (KCT) using a kaolin solution (Dade Behring, Liederbach, Germany).
Anticardiolipin antibodies (aCL) immunoglobulins (Ig) G and M, anti-beta2 glycoprotein I antibodies (aβ2GPI) IgG and IgM, and phosphatidylserine-dependent antiprothrombin antibodies (aPS/PT) IgG and IgM were assayed by enzyme-linked immunosorbent assay (ELISA) as described previously [2-4].
Brandt JT, Triplett DA, Alving B, Scharrer I. Criteria for the diagnosis of lupus anticoagulants: an update. On behalf of the Subcommittee on Lupus Anticoagulant/Antiphospholipid Antibody of the Scientific and Standardisation Committee of the ISTH. Thromb Haemost. 1995;74(4):1185–90.
Amengual O, Atsumi T, Khamashta MA, Koike T, Hughes GR. Specificity of ELISA for antibody to beta 2-glycoprotein I in patients with antiphospholipid syndrome. Br J Rheumatol. 1996;35(12):1239–43.
Atsumi T, Ieko M, Bertolaccini ML, Ichikawa K, Tsutsumi A, Matsuura E, et al. Association of autoantibodies against the phosphatidylserine-prothrombin complex with manifestations of the antiphospholipid syndrome and with the presence of lupus anticoagulant. Arthritis Rheum. 2000;43(9):1982–93.
Harris EN, Gharavi AE, Patel SP, Hughes GR. Evaluation of the anti-cardiolipin antibody test: report of an international workshop held 4 April 1986. Clin Exp Immunol. 1987;68(1):215–22.
We especially thank the participants, who made this study possible. We also thank Dr Mototsugu Doi, Dr Michihiro Kono, Dr Shun Tanimura and Dr Yusuke Ogata for their clinical contributions. We thank Dr Peter Y. Shane for assistance with the manuscript.
No specific funding was received to carry out the work described in this manuscript.
Rheumatology. 2019;58(6):969-974. © 2019 Oxford University Press