ANTIPHOSPHOLIPID SYNDROME (S ZUILY, SECTION EDITOR) How to Identify High-Risk APS Patients: Clinical Utility and Predictive Values of Validated Scores Kenji Oku 1 & Olga Amengual 1 & Shinsuke Yasuda 1 & Tatsuya Atsumi 1 # Springer Science+Business Media, LLC 2017 Abstract Purpose of Review Antiphospholipid syndrome (APS) is a clinical disorder characterised by thrombosis and/or preg- nancy morbidity in the persistence of antiphospholipid (aPL) antibodies that are pathogenic and have pro- coagulant activities. Thrombosis in APS tends to recur and require prophylaxis; however, the stereotypical treat- ment for APS patients is inadequate and stratification of the thrombotic risks is important as aPL are prevalently observed in various diseases or elderly population. Recent Findings It is previously known that the multiple positive aPL or high titre aPL correlate to thrombotic events. To progress the stratification of thrombotic risks in APS patients and to quantitatively analyse those risks, antiphospholipid score (aPL-S) and the Global Anti- phospholipid Syndrome Score (GAPSS) were defined. These scores were raised from the large patient cohort data and either aPL profile classified in detail (aPL-S) or simplified aPL profile with classical thrombotic risk fac- tors (GAPSS) was put into a scoring system. Both the aPL-S and GAPSS have shown a degree of accuracy in identifying high-risk APS patients, especially those at a high risk of thrombosis. However, there are several areas requiring improvement, or at least that clinicians should be aware of, before these instruments are applied in clin- ical practice. One such issue is standardisation of the aPL tests, including general testing of phosphatidylserine- dependent antiprothrombin antibodies (aPS/PT). Summary Additionally, clinicians may need to be aware of the patient’ s medical history, particularly with respect to the inci- dence of SLE, which influences the cutoff value for identify- ing high-risk patients. Keywords Antiphospholipid syndrome . Antiphospholipid antibodies . Antiphospholipid score . GAPSS Introduction Antiphospholipid syndrome (APS) is a clinical disorder characterised by thrombosis and/or pregnancy morbidity with persistent, pathogenic antiphospholipid (aPL) antibodies that have pro-coagulant activities [1–3]. Depending on the assay, aPL is reported in up to approximately 40% of patients with systemic lupus erythematosus (SLE) [4, 5]. There is solid evidence that thromboses in APS tend to recur and require prophylaxis [6, 7]; however, the stereotypical treatment for APS patients is often inadequate. Antiphospholipid antibodies are highly prevalent in patients with infectious diseases, autoimmune disorders, malignancies, and hepat- ic diseases and even in healthy elderly individuals [8–10]. The risk of thrombosis among healthy individ- uals who are incidentally found to have aPL is likely to be low (1% per year) [11] and only 40% of patients with aPL eventually develop APS manifestations in SLE [12, 13]. However, once thrombosis occurs in aPL car- riers and APS develops, the quality of life decreases greatly [14]. Thus, one of the most important clinical issues surrounding APS is the stratification of patients so that refractory cases receive intensive care and lower risk cases are not overtreated. This article is part of the Topical Collection on Antiphospholipid Syndrome * Kenji Oku kenoku@med.hokudai.ac.jp 1 Department of Medicine II, Hokkaido University Graduate School of Medicine, N15 W7, Kita-ku, Sapporo 060-8638, Japan Curr Rheumatol Rep (2017) 19:51 DOI 10.1007/s11926-017-0674-4