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Background: The APS ACTION International Clinical Database and Repository includes a secure web-based data capture system storing patient information including demographics, antiphospholipid antibodies (aPL)-related medical history, and aPL tests. Despite efforts at harmonization, inter-assay variability remains a problem in aPL testing. As a clinical repository open to researchers, ensuring comparability between assays and consistency in results between APS ACTION laboratories is essential to the validity of studies emerging from this network., Objective: To assess the level of agreement between an aPL-registry inclusion and core laboratory (core lab) anticardiolipin antibody (aCL) and anti-β 2 -glycoprotein-I antibody (aβ 2 GPI) ELISA testing results., Methods: Patients are recruited from 25 international centers based on positive aPL tests at inclusion. All samples are retested at the corresponding national APS ACTION core lab to confirm aPL positivity based on standard validated protocols. We analysed the categorical agreement, degree of linear association, and correlation between inclusion (local laboratory) and core lab aPL tests. Samples were included in this study only if results of aPL testing with ELISA at baseline were available., Results: 497 registry samples underwent confirmatory aPL tests. Categorical agreement between the inclusion and core lab values, as expressed by Cohen's kappa coefficients, ranged between 0.61 and 0.80 (as substantial agreement). The correlation between quantitative results in the aCL and aβ 2 GPI was better for IgM and IgA compared to IgG (Spearman rho 0.789 and 0.666 vs. 0.600 for aCL and rho 0.892 and 0.744 vs. 0.432 for aβ 2 GPI)., Conclusions: The results of inclusion for aCL and aβ 2 GPI tests used for recruitment into the registry were in agreement to the results obtained by the APS ACTION core laboratories; aCL and aβ 2 GPI results showed very good categorical agreement. This agreement increased when considering high titer (>40 units) samples. APS ACTION is a reliable and useful research resource for APS., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

In a previous systematic literature search, we demonstrated that the frequencies of antiphospholipid antibodies (aPL) in general-population patients with pregnancy morbidity (PM), deep vein thrombosis (DVT), myocardial infarction (MI), and stroke (ST) are 6%, 10%, 11%, and 14%. To determine the association between aPL and clinical outcomes, we conducted a follow-up analysis of the 120 studies included in the original paper. Based on the analysis of 81 studies, a significant difference in the frequency of aPL criteria tests between patients and controls emerged considering all the outcomes together (10% versus 3%). In particular, a significant difference was reported for overall PM, pregnancy loss (PrL), late PrL, severe preeclampsia (PEC), ST, MI, and DVT. No difference emerged for early PrL, intrauterine growth restriction (IUGR), PEC, eclampsia (EC), and HELLP. A positive association was found in more than half of the studies for overall PrL, severe PEC, HELLP, ST, MI, and DVT and in less than half for early and late PrL, PEC, EC, and IUGR. The positive association between aPL and clinical outcomes included in the antiphospholipid syndrome classification criteria is not supported by every study, being particularly inconsistent for early PL, IUGR, PEC, EC, and HELLP., (© The Author(s) 2015.)

Since the late 1980s some publications have proposed that antiphospholipid antibodies (aPL) may have some relationship with infertility, considering reported deleterious effects that aPL exert on trophoblast proliferation and growth. Although not included in current classification criteria for antiphospholipid syndrome, many physicians investigate for aPL in patients with a history of infertility, including antibodies not listed in classification criteria, and most of those patients will receive anticoagulant therapy if any of those antibodies have a result considered positive. A review of literature was conducted searching for studies that investigated the association of aPL and infertility and if aPL positivity alters in vitro fertilization (IVF) outcome. The definition of infertility, routine work-up to exclude other causes of infertility, definition of IVF failure as inclusion criteria and control populations were heterogeneous among studies. Most of them enrolled women over 40 years of age, and exclusion of other confounding factors was also inconsistent. Of 29 studies that assessed aPL positivity rates in infertile women, the majority had small sample sizes, implying a lack of power, and 13 (44.8%) reported higher frequency of aPL in infertile patients compared to controls, but most of them investigated a panel of non-criteria aPL tests, whose clinical significance is highly controversial. Only two studies investigated all three criteria tests, and medium-high titer of anticardiolipin cut-off conforming to international guidelines was used in one study. Considering IVF outcome, there was also disparity in this definition: few studies assessed the live birth rate, others the implantation rate. Of 14 publications that addressed the relationship between aPL and IVF outcome, only two described a detrimental effect of these autoantibodies. In conclusion, available data do not support an association between aPL and infertility, and aPL positivity does not seem to influence IVF outcome. Well-designed clinical studies recruiting women with a clear diagnosis of infertility and a high-risk aPL profile should be performed to test whether clinically relevant aPL do-or not-exert an effect on human fertility., (© The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.)

The presence of anti-phospholipid (aPL) is necessary but not sufficient to induce a thrombotic event. The "second hit" hypothesis suggested that an additional trigger may be needed to develop a vascular event in aPL carriers. In this article, pro and con of primary thromboprophylaxis in aPL carriers is deeply discussed, concluding that univocal data are not available, due to conflicting results of available clinical trials. However, in clinical practice the primary thromboprophylaxis is not indicated in all unselected asymptomatic aPL carriers, and the best strategy begin with the assessment of the peculiar risk profile of the subject. Thus, it is mandatory to eliminate modifiable prothrombotic risk factors (i.e. smoking, oral contraceptive), to treat the irreversible risk factors (i.e. hypertension, diabetes) and to introduce an aggressive prophylaxis with subcutaneous LMWH in high-risk situations (i.e. surgical procedures with prolonged immobilization). A different evaluation should be addressed to aPL carriers with a concomitant autoimmune disease that are considered as an additional pro-thrombotic risk factor. Similarly, concomitant positivity for more than one anti-phospholipid test confer a stronger risk of developing the thrombotic manifestations. Specific trials with larger cohorts of patients are needed to better clarify this issue., (Copyright © 2011. Published by Elsevier B.V.)