Incidence of a first thromboembolic event in asymptomatic carriers of high-risk antiphospholipid antibody profile: a multicenter prospective study. Blood. 2011;118:4714-4718. [PMID: 21765019 DOI: 10.1182/blood-2011-03-340232]

The impact of antibody profile in thrombosis associated with primary antiphospholipid syndrome

Triple positivity (TP) for antiphospholipid antibodies(aPL) may identify aPL carriers with poorer prognosis. The clinical impact of TP in primary antiphospholipid syndrome(PAPS) remains unclear and further clinical evidences are needed to validate TP as a marker of severity. The aim of this study was to evaluate the impact of TP on the clinical course of PAPS with thrombosis(t-PAPS). We performed a retrospective analysis of a cohort of t-PAPS patients, comparing groups of patients with TP and non-TP profiles according to their demographic, clinical and laboratory features. We included 105 patients with t-PAPS, the median follow-up time of 3.7 years. Twenty-two patients(21%) had TP; the demographic distribution, the presence of cardiovascular risk factors and the site of thrombosis were similar between TP and non-TP patients. The frequency of thrombotic events did not differ between TP and non-TP patients during the study period. Pregnancy morbidities were more frequent in women with t-PAPS and TP than in those with non-TP profile (80% vs. 52.8%, P = 0.05). Patients with t-PAPS and TP presented, at diagnosis, higher dRVVT ratio (median R = 2.44 vs. 1.57, P < 0.0001), higher aCL titer (median = 50UI vs. 35 UI, P < 0.0001), lower C3 levels (median = 1.08 vs. 1.30 mg dL^-1 , P = 0.001), lower C4 levels (median = 0.22 vs. 0.25 mg dL^-1 , P = 0.05) and higher frequency of positive ANA test (50% vs. 20%, P = 0.008) than patients with t-PAPS and non-TP. Lower-than-normal levels of C3 was independently associated with TP (OR = 5.1, P = 0.02). The presence of TP in patients with t-PAPS was associated with immune derangement, with no effect on the clinical course of the disease.

Antiplatelet and anticoagulant agents for secondary prevention of stroke and other thromboembolic events in people with antiphospholipid syndrome

BACKGROUND

Antiphospholipid syndrome (APS) is a systemic autoimmune disease characterized by arterial or venous thrombosis (or both) and/or pregnancy morbidity in association with the presence of antiphospholipid antibodies. The prevalence is estimated at 40 to 50 cases per 100,000 people. The most common sites of thrombosis are cerebral arteries and deep veins of the lower limbs. People with a definite APS diagnosis have an increased lifetime risk of recurrent thrombotic events.

OBJECTIVES

To assess the effects of antiplatelet or anticoagulant agents, or both, for the secondary prevention of recurrent thrombosis, particularly ischemic stroke, in people with antiphospholipid syndrome.

SEARCH METHODS

We searched the Cochrane Stroke Group Trials Register (February 2017), CENTRAL (last search February 2017), MEDLINE (from 1948 to February 2017), Embase (from 1980 to February 2017), and several ongoing trials registers. We also checked the reference lists of included studies, systematic reviews, and practice guidelines, and we contacted experts in the field.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) that evaluated any anticoagulant or antiplatelet agent, or both, in the secondary prevention of thrombosis in people diagnosed with APS according to the criteria valid when the study took place. We did not include studies specifically addressing women with obstetrical APS.

DATA COLLECTION AND ANALYSIS

Pairs of review authors independently selected studies for inclusion, extracted data, and assessed the risk of bias for the included studies. We resolved any discrepancies through discussion or by consulting a third review author and, in addition, one review author checked all the extracted data.

MAIN RESULTS

We included five studies involving 419 randomized participants with APS. Only one study was at low risk of bias in all domains. One study was at low risk of bias in all domains for objective outcomes but not for quality of life (measured using the EQ-5D-5L questionnaire). We judged the other three studies to be at unclear or high risk of bias in three or more domains.The duration of intervention ranged from 180 days to a mean of 3.9 years. One study compared rivaroxaban (a novel oral anticoagulant: NOAC) with standard warfarin treatment and reported no thrombotic or major bleeding events, but it was not powered to detect such differences (low-quality evidence). Investigators reported similar rates of clinically relevant non-major bleeding (risk ratio (RR) 1.45, 95% confidence interval (CI) 0.25 to 8.33; moderate-quality evidence) and minor bleeding (RR 1.21, 95% CI 0.51 to 2.83) for participants receiving rivaroxaban and the standard vitamin K antagonists (VKA). This study also reported some small benefit with rivaroxaban over the standard VKA treatment in terms of quality of life health state measured at 180 days with the EQ-5D-5L 100 mm visual analogue scale (mean difference (MD) 7 mm, 95% CI 2.01 to 11.99; low-quality evidence) but not measured as health utility (MD 0.04, 95% CI -0.02 to 0.10 [on a scale from 0 to 1]).Two studies compared high dose VKA (warfarin) with moderate/standard intensity VKA and found no differences in the rates of any thrombotic events (RR 2.22, 95% CI 0.79 to 6.23) or major bleeding (RR 0.74, 95% CI 0.24 to 2.25) between the groups (low-quality evidence). Minor bleeding analyzed using the RR and any bleeding using the hazard ratio (HR) were more frequent in participants receiving high-intensity warfarin treatment compared to the standard-intensity therapy (RR 2.55, 95% CI 1.07 to 6.07; and HR 2.03, 95% CI 1.12 to 3.68; low-quality evidence).In one study, it was not possible to estimate the RR for stroke with a combination of VKA plus antiplatelet agent compared to a single antiplatelet agent, while for major bleeding, a single event occurred in the single antiplatelet agent group. In one study, comparing combined VKA plus antiplatelet agent with dual antiplatelet therapy, the RR of the risk of stroke over three years of observation was 5.00 (95% CI 0.26 to 98.0). In a single small study, the RR for stroke during one year of observation with a dual antiplatelet therapy compared to single antiplatelet drug was 0.14 (95% CI 0.01 to 2.60).

AUTHORS' CONCLUSIONS

There is not enough evidence for or against NOACs or for high-intensity VKA compared to the standard VKA therapy in the secondary prevention of thrombosis in people with APS. There is some evidence of harm for high-intensity VKA regarding minor and any bleeding. The evidence was also not sufficient to show benefit or harm for VKA plus antiplatelet agent or dual antiplatelet therapy compared to a single antiplatelet drug. Future studies should be adequately powered, with proper adherence to treatment, in order to evaluate the effects of anticoagulants, antiplatelets, or both, for secondary thrombosis prevention in APS. We have identified five ongoing trials mainly using NOACs in APS, so increasing experimental efforts are likely to yield additional evidence of clinical relevance in the near future.

Primary thromboprophylaxis with low-dose aspirin and antiphospholipid antibodies: Pro's and Con's

Whether primary prophylaxis should be prescribed in individuals with antiphospholipid antibodies (aPL) remains controversial due to the lack of relevant evidence-based data. Indeed, it is unclear whether the benefit of LDA outweighs the risk of major bleeding associated with LDA in a low-risk population. On the contrary, stratification of aPL-positive subjects according to their aPL profile (combination, isotype and titer), presence of other concomitant risk factors for thrombosis and coexistence of an underling autoimmune disease is essential to decide whether primary prophylactic therapy should be prescribed. Additionally, the management of modifiable thrombotic risk factors is a necessary strategy, and the use of transient prophylaxis is crucial during high-risk periods. Specifically designed prospective trials are urgently needed to determine the real prophylactic impact of aspirin, as well as of alternative or concomitant therapeutic strategies such as hydroxychloroquine, statins or DOACS in aPL positive patients.

Increased heterogeneity of brain perfusion is an early marker of central nervous system involvement in antiphospholipid antibody carriers

Objective

The non-criteria neuropsychiatric manifestations of antiphospholipid syndrome include headache, dizziness, vertigo, seizure, depression and psychosis. There were still no objective methods qualified to detect the early central nervous system involvement in non-criteria antiphospholipid syndrome. We evaluated the effectiveness of Tc-99m ECD SPECT in assessing circulatory insufficiency in the brains of patients with antiphospholipid antibodies and neuropsychiatric symptoms but without thromboembolism.

Materials and methods

Patients with a history of positive antiphospholipid antibodies and neuropsychiatric symptoms composed the case group; patients without antiphospholipid antibody served as the control group. Subjects with a history of thromboembolism or autoantibodies to extractable nuclear antigens were excluded. All patients received Tc-99m ECD SPECT studies and were classified by the number of positive antiphospholipid antibodies they carried. The heterogeneity of brain perfusion was defined as the coefficient of variation of the SPECT signals. Analysis of variance (ANOVA) was applied to evaluate the differences between the groups.

Results

Total 60 adult patients were included in this study. There were 54 patients in the case group and 6 patients in the control group. The mean age was 38.3 ± 11.5 years. There were 52 women and 8 men. There was no significant difference in the mean brain perfusion between groups (P = 0.69). However, Tc-99m ECD SPECT demonstrated significant heterogeneity of brain perfusion in relation to the number of antiphospholipid antibodies (P = 0.01).

Conclusions

This is the first study demonstrating that Tc-99m ECD SPECT can early detect the increased heterogeneity of brain circulation in non-criteria antiphospholipid antibody carriers.

Hydroxychloroquine in the primary thrombosis prophylaxis of antiphospholipid antibody positive patients without systemic autoimmune disease

Objective The objective of this study was to determine the efficacy of hydroxychloroquine (HCQ) in the primary thrombosis prevention of antiphospholipid antibody (aPL)-positive patients with no other systemic autoimmune diseases. Methods Under the auspices of Antiphospholipid Syndrome Alliance for Clinical Trials and International Networking, a multicenter, international, randomized controlled trial (RCT) was initiated, in which persistently aPL-positive but thrombosis-free patients without systemic autoimmune diseases were randomized to receive HCQ or no treatment in addition to their standard regimen. The primary objective was the efficacy of HCQ in preventing the first thrombosis. The secondary objectives were the thrombosis incidence rate, and the effects of HCQ on aPL profile and mortality rate. Patients were risk-stratified based on antiplatelet agent use. The goal was to follow patients every 6 months for 5 years. Results We recruited 20 persistently aPL-positive patients (female: 19, mean age: 46.6 ± 9.9 years, and baseline antiplatelet medication: 14); 9/20 were randomized to HCQ. During the mean follow-up of 1.7 years, no patients developed thrombosis or a serious adverse event. The study was terminated early due to the low recruitment rate, exacerbated by the prolonged manufacturing shortage and significant price increase of HCQ in the United States. Conclusion Given that a small number of patients with a relatively short follow-up were enrolled in our RCT, and no patients developed thrombosis, we cannot accurately assess the effectiveness of HCQ for primary thrombosis prevention in persistently aPL-positive patients with no other systemic autoimmune diseases. Our experience suggests that conducting an international RCT, especially without pharmaceutical support, is an extremely challenging undertaking.

Diagnosis and management of the antiphospholipid syndrome

Antiphospholipid syndrome (APS) is characterized by thrombosis and/or pregnancy complications in the presence of persistent antiphospholipid antibodies (APLA). Laboratory diagnosis of APLA depends upon the detection of a lupus anticoagulant, which prolongs phospholipid-dependent anticoagulation tests, and/or anticardiolipin (aCL) and anti-β2-glycoprotein-1 (β2GPI) antibodies. APLA are primarily directed toward phospholipid binding proteins. Pathophysiologic mechanisms underlying thrombosis and pregnancy loss in APS include APLA induced cellular activation, inhibition of natural anticoagulant and fibrinolytic systems, and complement activation, among others. There is a high rate of recurrent thrombosis in APS, especially in triple positive patients (patients with lupus anticoagulant, aCL and anti-β2GPI antibodies), and indefinite anticoagulation with a vitamin K antagonist is the standard of care for thrombotic APS. There is currently insufficient evidence to recommend the routine use of direct oral anticoagulants (DOAC) in thrombotic APS. Aspirin with low molecular weight or unfractionated heparin may reduce the incidence of pregnancy loss in obstetric APS. Recent insights into the pathogenesis of APS have led to the identification of new potential therapeutic interventions, including anti-inflammatory and immunomodulatory therapies. Additional research is needed to better understand the effects of APLA on activation of signaling pathways in vascular cells, to identify more predictive biomarkers that define patients at greatest risk for a first or recurrent APLA-related clinical event, and to determine the safety and efficacy of DOACs and novel anti-inflammatory and immune-modulatory therapies for refractory APS.

Clinical characteristics and thrombosis outcomes of paediatric antiphospholipid syndrome: analysis of 58 patients

The study aims to analyse the clinical and immunological manifestations of paediatric antiphospholipid syndrome (APS) in patients, based on the 2006 revised classification criteria of definite APS. Fifty-eight paediatric patients with APS were enrolled and analysed retrospectively. A total of 37 female and 21 male patients with a mean age of 14 ± 3 years at disease onset were included. Fourteen (24%) cases were primary APS, and 40 (69%) cases were secondary to systemic lupus erythaematosus (SLE). Anti-nuclear antibody (ANA) positivity and hypocomplementemia were more common in secondary APS than in primary APS. The most common manifestations of thrombosis were deep vein thrombosis of the lower extremities (25 cases, 37%). Non-thrombotic manifestations were mainly immunologic thrombocytopenia, autoimmune haemolytic anaemia, skin lesions, arthritis, pulmonary hypertension, heart valve vegetations and spontaneous abortion. LA, ACL and anti-β2GPI were positive in 42 (95%), 28 (64%) and 34 (77%) cases, respectively. Over half (23 cases, 52%) of the patients were triple-positive for antiphospholipid (aPL) antibodies. Among patients with single-positive LA and anti-β2GPI, the proportion with venous thrombosis was 100% (5 cases) and 0% (0 cases), respectively. The arterial thrombosis proportions were 22% (5 cases), 21% (3 cases) and 14% (1 case) in the triple-, double- and single-aPL-positive groups, respectively (P > 0.05). Fifty-three (91%) cases were followed up for 3 to 140 months, with a median time of 32 months. Seven (13%) cases had recurrences or appearances of thrombosis during follow-up, all of which were double- or triple-aPL positive. APS in the paediatric patients is mostly secondary to SLE. ANA positivity and hypocomplementemia are more common in secondary APS, but there are no differences in the other clinical manifestations between the primary and secondary APS groups. Deep vein thrombosis is the most common thrombotic event. Positive LA may increase the risk of venous thrombosis. Multiple-aPL positivity does not increase the proportion of thrombosis. Long-term anticoagulant or antiplatelet therapy is needed to prevent thrombosis recurrence in double- or triple-positive aPL cases.

Incidence of thromboembolic events in asymptomatic carriers of IgA anti ß2 glycoprotein-I antibodies

BACKGROUND

The antiphospholipid syndrome (APS) is defined by simultaneous presence of vascular clinical events and antiphospholipid antibodies (aPL). The aPL considered as diagnostics are lupus anticoagulant and antibodies anticardiolipin (aCL) and anti-ß2 glycoprotein-I (aB2GP1). During recent years, IgA aB2GP1 antibodies have been associated with thrombotic events both in patients positive, and mainly negative for other aPL, however its value as a pro-thrombotic risk-factor in asymptomatic patients has not been well defined.

OBJECTIVE

To test the role of IgA anti B2GP1 as a risk factor for the development of APS-events (thrombosis or pregnancy morbidity) in asymptomatic population with a 5-year follow-up.

METHODS

244 patients isolated positive for anti-beta2-glycoprotein I IgA (Group-1 study) and 221 negative patients (Group-2 control) were studied. All the patients were negative for IgG and IgM aCL.

RESULTS

During the follow-up, 45 patients (9.7%) had APS-events, 38 positive for IgA-aB2GP1 and 7 negative (15.6% vs 3.2%, p<0.001). The incidence rate of APS-events was 3.1% per year in IgA-aB2GP1 positive patients and 0.6% per year in the control group. Arterial thrombosis were the most frequent APS-events (N = 25, 55%) and were mainly observed in Group-1 patients (21 vs 4, p = 0.001). Multivariate analysis were shown as independent risk-factors for the development of APS-events, age, sex (men) and presence of IgA-aB2GP1 (odds ratio 5.25, 95% CI 2.24 to 12.32).

CONCLUSION

The presence of IgA-aB2GP1 in people with no history of APS-events is the main independent risk factor for the development of these types of events, mainly arterial thrombosis.

Reduction of annexin A5 anticoagulant ratio identifies antiphospholipid antibody-positive patients with adverse clinical outcomes

Essentials Annexin A5 resistance is a mechanism for antiphospholipid (aPL) syndrome. 750 patients with history of thrombosis, pregnancy complications and controls were tested. Reduced annexin A5 anticoagulant ratios (A5R) correlate with aPL antibody multipositivity. Reduced A5R may identify patients with a propensity for thrombosis or pregnancy complications. Click to hear an ISTH Academy presentation on antiphospholipid antibody syndrome by Drs de Laat and Bertolaccini SUMMARY: Background Annexin A5 (A5) is a potent anticoagulant protein that shields anionic phospholipids from coagulation reactions. Previous studies showed that antibodies from patients with antiphospholipid (aPL) syndrome (APS) interfere with annexin A5 crystallization and anticoagulant activity. Objective The purpose of this study was to investigate whether reduced values in the annexin A5 anticoagulant ratio (A5R) assay (i.e. 'annexin A5 resistance') are associated with adverse clinical events in aPL antibody-positive patients. Patients/Methods In an initial discovery phase, a group of 679 patient samples from a 'real-world' tertiary care hospital population were tested for A5R. This was followed by a validation-phase cohort of 71 asymptomatic patients with aPL antibodies and no prior history of an adverse clinical event whose baseline samples were tested for A5R then subsequently observed for up to 4 years. Results In the discovery-phase group, we found a reduction of A5R in aPL antibody-positive patients with thrombosis and/or pregnancy complications compared with aPL antibody-negative patients and controls. In addition, reduced A5R values in both the discovery-phase group and validation-phase cohort correlated with the extent of multi-positivity for standard APS tests, which has also been shown to be associated with a risk of adverse clinical outcomes. Conclusion Reduced A5R values were associated with a multi-positivity profile in aPL antibody-positive patients within both groups and with the development of adverse clinical events.

Pathogenesis and management of antiphospholipid syndrome

Antiphospholipid antibodies are a heterogeneous group of autoantibodies that have clear associations with thrombosis and pregnancy morbidity, and which together constitute the 'antiphospholipid syndrome' (APS). However, the pathophysiology of these complications is not well understood and their heterogeneity suggests that more than one pathogenic process may be involved. Diagnosis remains a combination of laboratory analysis and clinical observation but there have been significant advances in identifying specific pathogenic features, such as domain I-specific anti-β2-glycoprotein-I antibodies. This in turn has pointed to endothelial and complement activation as important factors in the pathogenesis of APS. Consequently, although anticoagulation remains the standard treatment for thrombotic APS and during pregnancy, the realisation that these additional pathways are involved in the pathogenesis of APS has significant implications for treatment: agents acting outside the coagulation system, such as hydroxychloroquine for pregnancy complications and sirolimus as an inhibitor of the mammalian target of rapamycin (mTOR) pathway, are now under evaluation and represent a radical change in thinking for haematologists. Conventional anticoagulation is also under challenge from new, direct acting anticoagulants. This review will provide a comprehensive overview of the evolving understanding of APS pathogenesis and how this and novel therapeutics will alter diagnosis and management.

Autoantibodies to domain 1 of beta 2 glycoprotein I determined using a novel chemiluminescence immunoassay demonstrate association with thrombosis in patients with antiphospholipid syndrome

INTRODUCTION

Antibodies to the domain 1 of beta 2 glycoprotein I (β2GPI-D1) have been suggested as a risk marker for thrombosis in patients with the antiphospholipid syndrome (APS). This cross-sectional study aimed to analyze the clinical utility of a novel chemiluminescence assay for the detection of anti-β2GPI-D1 antibodies.

PATIENTS AND METHODS

Sera collected from patients with primary or secondary APS (n = 106; 72 with and 34 without history of thrombosis) and controls (n = 272) were tested for anti-β2GPI-D1 IgG by chemiluminescence assay (QUANTA Flash) and by two anti-β2GPI IgG assays (QUANTA Lite and QUANTA Flash β2GPI IgG).

RESULTS

Anti-β2GPI-D1 IgG titers were significantly higher in patients with thrombosis (P = 0.0032) than those without. At the cut-off of 20 units, which yielded a 99.5% specificity, 24 of 72 (34.9%) patients with thrombosis and four of 34 (11.8%) without thrombosis were anti-β2GPI-D1 IgG positive (odds ratio, OR = 4.0). By further optimizing the cut-off specifically for correlation with thrombosis, 20.8% of the patients with thrombosis and 2.9% of the patients without thrombosis were positive (OR = 8.7). The ORs were significantly lower for antibodies to the full-length β2GPI by either the chemiluminescence assay or ELISA. Using the anti-β2GPI chemiluminescence assay, the OR was 2.3 (recommended cut-off of 20 CU) or 4.1 (optimal cut-off 164.6 CU). Using the anti-β2GPI ELISA, the OR was 2.7 (recommended cut-off of 20 units) or 3.7 (optimal cut-off 7.6 units).

CONCLUSION

These data indicate that anti-β2GPI-D1 IgG are present more frequently and in higher titers in APS patients with thrombotic complications than in those without.The novel β2GPI-D1 chemiluminescence assay appears to be superior to full-length β2GPI assays for the risk assessment of thrombotic events in APS patients.

Diagnosis and treatment of antiphospholipid syndrome in childhood: A review

The antiphospholipid syndrome (APS) is a multisystem autoimmune disease characterized by recurrent fetal loss and thromboembolic events associated with the presence of elevated titres of antiphospholipid antibodies (aPL). The purpose of this review is to summarize what is currently known about the diagnosis and treatment of pediatric APS, to highlight key differences between APS presenting in adults versus children throughout, and to identify areas where future research is needed.

Recent advances in understanding antiphospholipid syndrome

Antiphospholipid syndrome (APS), also known as Hughes Syndrome, is a systemic autoimmune disease characterized by thrombosis and/or pregnancy morbidity in the presence of persistently positive antiphospholipid antibodies. A patient with APS must meet at least one of two clinical criteria (vascular thrombosis or complications of pregnancy) and at least one of two laboratory criteria including the persistent presence of lupus anticoagulant (LA), anticardiolipin antibodies (aCL), and/or anti-b2 glycoprotein I (anti-b2GPI) antibodies of IgG or IgM isotype at medium to high titres in patient’s plasma. However, several other autoantibodies targeting other coagulation cascade proteins (i.e. prothrombin) or their complex with phospholipids (i.e. phosphatidylserine/prothrombin complex), or to some domains of β2GPI, have been proposed to be also relevant to APS. In fact, the value of testing for new aPL specificities in the identification of APS in thrombosis and/or pregnancy morbidity patients is currently being investigated.

The Laboratory Diagnosis of the Antiphospholipid Syndrome

The Antiphospholipid Syndrome (APS) is classified based on the presence of both clinical and laboratory criteria. Both sets of criteria are subject to much review and intense research as it is becoming increasingly clear that no single test is specific for defining this autoimmune disorder. A number of leading international bodies have released guidelines in an attempt to improve the laboratory testing and reporting. The current review is an appraisal of some of the literature pertaining to the laboratory testing.

Persistent triple antiphospholipid antibody positivity as a strong risk factor of first thrombosis, in a long-term follow-up study of patients without history of thrombosis or obstetrical morbidity

Introduction The long-term risk of first thrombosis and benefit of prophylaxis in antiphospholipid antibody (aPL) carriers without history of thrombosis or obstetrical morbidity is poorly known. This study aimed to evaluate the long-term rate and risk factors associated with a first thrombosis in those patients. Patients and methods After a prior study ended in December 2005 and was already published, we extended the follow-up period of our cohort of aPL carriers. Results Ninety-eight of the 103 patients of the previous study were included. The annual first thrombosis rate was 2.3% per patient-year during a median of 13 years (6-17). None of the baseline characteristics was predictive of risk of first thrombosis, but persistent aPL over time were associated with an increased risk. The stronger association was found in triple aPL-positive carriers: OR 3.38 (95% CI: 1.24-9.22). Of note, conversely to our previous findings, no benefit of aspirin prophylaxis was observed. Conclusion The risk of first thrombosis in aPL carriers without history of thrombosis or obstetrical morbidity was significant, persisted linearly over time and was associated with persistent aPL. This risk was especially increased in triple aPL-positive carriers, in whom a close follow-up seems to be necessary. Nevertheless, the benefit of aspirin prophylaxis remained unclear.

Thrombotic risk assessment in antiphospholipid syndrome: the role of new antibody specificities and thrombin generation assay

Antiphospholipid syndrome (APS) is an autoimmune condition characterized by the presence of antiphospholipid antibodies (aPL) in subjects presenting with thrombosis and/or pregnancy loss. The currently used classification criteria were updated in the international consensus held in Sidney in 2005. Vascular events seem to result of local procoagulative alterations upon triggers influence (the so called “second-hit theory”), while placental thrombosis and complement activation seem to lead to pregnancy morbidity. The laboratory tests suggested by the current classification criteria include lupus anticoagulant, a functional coagulation assay, and anticardiolipin and anti-β2-glycoprotein-I antibodies, generally detected by solid phase enzyme-linked immunosorbent assay. The real challenge for treating physicians is understanding what is the actual weight of aPL in provoking clinical manifestations in each case. As thrombosis has a multi-factorial cause, each patient needs a risk-stratified approach. In this review we discuss the role of thrombotic risk assessment in primary and secondary prevention of venous and arterial thromboembolic disease in patients with APS, focusing on new antibody specificities, available risk scoring models and new coagulation assays.

The antiphospholipid syndrome: from pathophysiology to treatment

Antiphospholipid antibody syndrome (APS) is an autoimmune acquired thrombophilia characterized by recurrent thrombosis and pregnancy morbidity in the presence of antiphospholipid antibodies (aPL). APS can be primary, if it occurs in the absence of any underlying disease, or secondary, if it is associated with another autoimmune disorder, most commonly systemic lupus erythematosus. The exact pathogenetic mechanism of APS is unknown, but different, not mutually exclusive, models have been proposed to explain how anti-PL autoantibodies might lead to thrombosis and pregnancy morbidity. Diagnosis of APS requires that a patient has both a clinical manifestation (arterial or venous thrombosis and/or pregnancy morbidity) and persistently positive aPL, but the clinical spectrum of the disease encompasses additional manifestations which may affect every organ and cannot be explained exclusively by a prothrombotic state. Treatment for aPL-positive patients is based on the patient's clinical status, presence of an underlying autoimmune disease, and history of thrombotic events. In case of aPL positivity without previous thrombotic events, the treatment is mainly focused on reduction of additional vascular risk factors, while treatment of patients with definite APS is based on long-term anticoagulation. Pregnancy complications are usually managed with low-dose aspirin in association with low molecular weight heparin. Refractory forms of APS could benefit from adding hydroxychloroquine and/or intravenous immunoglobulin to anticoagulation therapy. Promising novel treatments include anti-B cell monoclonal antibodies, new-generation anticoagulants, and complement cascade inhibitors. The objective of this review paper is to summarize the recent literature on APS from pathogenesis to current therapeutic options.

Performance Characteristics of Commercial Immunoassays for the Detection of IgG and IgM Antibodies to β2 Glycoprotein I and an Initial Assessment of Newly Developed Reference Materials for Assay Calibration

OBJECTIVES

To investigate the performance characteristics and impact of newly developed reference calibrators on the commutability between anti-β2 glycoprotein I (anti-β2 GPI) immunoassays in antiphospholipid syndrome (APS) and/or systemic lupus erythematosus (SLE).

METHODS

Immunoglobulin G (IgG) and immunoglobulin M (IgM) anti-β2 GPI immunoassays from four manufacturers were evaluated. Serum samples from 269 patients (APS only, n = 31; SLE and APS, n = 83; SLE only, n = 129; pregnancy-related clinical manifestations without APS, n = 26) and 162 women with histories of successful pregnancies were tested. Results were expressed in kit-specific arbitrary units and in the calibrator reference units (RUs) based on 99th percentile cutoff values. Diagnostic accuracies, correlation between kits, and specific clinical manifestations in APS were investigated.

RESULTS

The sensitivities of the assays ranged from 15.8% to 27.2% (IgG) and 12.3% to 15.8% (IgM) while specificities ranged from 79.4% to 86.5% (IgG) and 80.6% to 84.5% (IgM). There was moderate to almost perfect interassay reliability (Cohen κ, 0.69-0.98), and Spearman correlation coefficients were generally improved when results of the IgG determinations were expressed in RUs.

CONCLUSIONS

Although qualitative agreements between immunoassays for both antibody isotypes are acceptable, correlations with APS clinical manifestations were kit dependent. Only the use of IgG reference material improved quantitative correlations between assays.

Laboratory testing for antiphospholipid syndrome

This is a practical report on laboratory tests for the diagnosis of antiphospholipid syndrome (APS). After a general definition of APS, this study deals with appropriateness and timing in requesting the determination of antiphospholipid (aPL) antibodies. Lupus anticoagulant (LAC), anticardiolipin (aCL), and anti β2-glycoprotein I (aβGPI) are the mandatory tests to be performed, while other tests are not yet validated for clinical use. Interpretation of results is an important discussed issue that implies a close liaison between clinical pathologists and clinicians. Finally, a personal definition of APS according to aPL antibody profile closes the manuscript.

Current status and future prospects for the treatment of antiphospholipid syndrome

Antiphospholipid syndrome (APS) is a prothrombotic disease characterized by thrombosis and pregnancy morbidity in the presence of antiphospholipid antibodies (apL). Management of thrombosis is based on long-term oral anticoagulation and patients with arterial events should be treated aggressively. Primary thrombo-prophylaxis is recommended in patients with systemic lupus erythromatosus (SLE) and obstetric APS. Obstetric APS care is based on high-risk management and treatment with aspirin and heparin. Possible future therapies include statins, hydroxychloroquine, rituximab, and new anticoagulant drugs. Current research is focused on targeting components of the complement system, interfering with aPL-mediated cell activation and using tailored peptides to block the pathogenic subpopulation of aPL.

Presence of Antiphospholipid Antibodies as a Risk Factor for Thrombotic Events in Patients with Connective Tissue Diseases and Idiopathic Thrombocytopenic Purpura

OBJECTIVE

Antiphospholipid syndrome (APS) is a well-known complication of habitual abortion and/or thrombosis and is frequently associated with autoimmune diseases.

METHODS

We retrospectively investigated the relationships between the presence of antiphospholipid antibodies (aPLs) and the incidence of thrombotic events (THEs) in 147 patients with various connective tissue diseases (CTD) suspected of having APS and 86 patients with idiopathic thrombocytopenic purpura (ITP). THEs were observed in 41 patients, including 14 cases of venous thrombosis, 21 cases of arterial thrombosis and eight cases of complications of pregnancy.

RESULTS

The prevalence of THE was significantly high in the systemic lupus erythematosus (SLE) patients compared with the other CTD patients and ITP patients. The frequency of lupus anticoagulant (LA), anticardiolipin antibodies (aCL)-β2-glycoprotein (GPI) complex IgG and aPL was significantly high in the SLE patients compared with the ITP patients. Subsequently, the rate of development of THE was significantly high in the patients with aPLs. In particular, the incidence of THE was significantly high in the SLE or ITP patients with LA, aCL-β2GPI IgG or aPL. The optimal cut-off values for LA, aCL IgG and aCL-β2GPI complex IgG for the risk of THEs were higher in the SLE patients in comparison to the values obtained when using the kit provided by the manufacturer.

CONCLUSION

Although aPLs is frequently associated with SLE and is a causative factor for thrombosis, the optimal cut-off value for aPL for predicting the occurrence of THEs varies among different underlying diseases.

Pediatric antiphospholipid syndrome

Antiphospholipid syndrome (APS) is a multisystem autoimmune condition characterized by vascular thromboses associated with persistently positive antiphospholipid antibodies. There is currently a paucity of data (incidence, prevalence, thrombosis risk, and effective treatment) in pediatric APS. The purpose of this report is to review the current literature on APS in children and neonates, identify the gaps in current knowledge, and suggest avenues for studies to fill those gaps.

Patients with antiphosholipid syndrome and thrombotic recurrences: A real world observation (the Piedmont cohort study)

BACKGROUND

Patients with antiphospholipid syndrome (APS) often have thrombotic recurrences, sometimes despite appropriate ongoing anticoagulant treatment. Identifying APS vascular patients at high risk for thrombotic recurrences is still an unsolved issue.

OBJECTIVES

To report the real-life experience of thrombotic recurrences in APS patients included in the Piedmont observational cohort study, and evaluate clinical and laboratory risk factors for thrombotic recurrences.

PATIENTS

A multi-centre observational study was performed by enrolling 177 patients with vascular APS (primary APS in 99 subjects (56%)); the median follow-up was five years (range 1-26 years).

RESULTS

The observed thrombotic recurrence rate was about 7.5/100 patient years in the first five years after the first thrombotic event. While the first recurrence often occurred (45%) in patients who were not on oral anticoagulant therapy (OAT), the second recurrence mainly occurred despite ongoing OAT (80%). However, due to the real-life observational nature of this study, treatment was based on the treating physician's judgement, and no structured therapeutic protocol was applied. Moreover, compliance with OAT was not available. No differences in antiphospholipid antibodies (aPL) profile were observed between patients with or without thrombotic recurrences, but a high risk aPL profile (Miyakis type 1 and 2a) was present in 96% of our patients, 26% of whom had triple positivity. Diabetes (p < 0.01, OR 10), inherited thrombophilia (p < 0.0078, OR 4) and OAT withdrawal were independent risk factors for recurrences.

CONCLUSIONS

With the limit of a real-life observational cohort study, the thrombotic recurrence rate in APS was as high as 7.5/100 patient years in the first five years after the first thrombotic event. OAT discontinuation, diabetes and inherited thrombophilia, when associated with a high-risk aPL profile, are risk factors for thrombotic recurrences.

Antiphospholipid Antibodies and Recurrent Thrombotic Events: Persistence and Portfolio

BACKGROUND

There are very limited prospective data on the significance of persistent antiphospholipid antibodies (aPL) and recurrent thrombo-occlusive events (TOEs). We investigated the prognostic value of (1) 2 newer aPL assays, (2) an aPL portfolio and (3) persistent aPL positivity following stroke.

METHODS

A total of 1,770 subjects from the APASS-WARSS study underwent further aPL testing for antibodies to phosphatidylserine (aPS) and anti-β2-glycoprotein-I (anti-β2GPI) from stored sera. Follow-up aPL status was also tested in a subset of subjects. Primary analysis was based on time to any TOE (ischemic stroke, myocardial infarction, transient ischemic attack, deep vein thrombosis, pulmonary embolism or systemic arterial occlusion)/death at 2 years. Cox proportional hazard analyses assessed whether aPL independently related to outcome.

RESULTS

Persistent anti-β2GPI decreased the time to TOE/death after adjustment for potential confounders (hazards ratio (HR) 2.86, 95% CI 1.21-6.76, p = 0.017). When persistent anti-β2GPI was combined with another persistently positive aPL, time to TOE/death was also reduced (HR 3.79, 95% CI 1.18-12.14, p = 0.025). Neither persistent anticardiolipin antibodies nor persistent aPS alone nor a single positive anti-β2GPI nor aPS was associated with decreased time to TOE/death. No single positive aPL, portfolio of baseline aPL or any persistent aPL increased the rate of TOE/death.

CONCLUSIONS

Rates of TOE/death were not influenced by aPL results at baseline or follow-up. Persistent anti-β2GPI alone, and with persistent second aPL, was independently associated with decreased time to TOE/death. Persistent aPL, an aPL portfolio and newer aPL in ischemic stroke patients are not helpful in predicting an increased rate of recurrent TOEs.

Thrombocytopenic syndromes in pregnancy

The physiological changes in pregnancy result in platelet counts that are lower than in nonpregnant women. Consequently, thrombocytopenia is a common finding occurring in 7-12% of pregnant women. Gestational thrombocytopenia, the most common cause of low platelet counts, tends to be mild in most women and does not affect maternal, fetal or neonatal outcomes. Gestational thrombocytopenia needs to be distinguished from other less common causes of isolated thrombocytopenia, such as immune thrombocytopenia, which affects approximately 3% of thrombocytopenic pregnant women and can lead to neonatal thrombocytopenia. Hypertensive disorders of pregnancy and thrombotic microangiopathies are both associated with thrombocytopenia. They share a considerable number of similar characteristics and are associated with significant maternal and neonatal morbidity and rarely mortality. Accurate identification of the aetiology of thrombocytopenia and appropriate management are integral to optimizing the pregnancy, delivery and neonatal outcomes of this population. Clinical cases are described to illustrate the various aetiologies of thrombocytopenia in pregnancy and their treatment.

Clinical utility of automated chemiluminescent antiphospholipid antibody assay

BACKGROUND

The threshold for clinically relevant levels of antiphospholipid (aPL) antibodies for the diagnosis of antiphospholipid syndrome (APS) remains a matter of debate. As new technologies for antibody detection are introduced, their performance characteristics must be clearly understood and compared to traditional assays.

OBJECTIVES

To assess the analytical performance and clinical utility of fully automated anticardiolipin (aCL) and anti-β2 glycoprotein I (aβ2GPI) chemiluminescent immunoassays (CIA) in comparison to the traditional ELISA tests.

PATIENTS/METHODS

Samples from 220 autoimmune patients were studied (primary APS - 74; secondary APS - 47, systemic lupus erythematosus (SLE) without APS - 99). All samples were tested for IgG and IgM aCL and β2GPI antibodies using both CIA and ELISA, and for lupus anticoagulant (LAC).

RESULTS

Good qualitative agreement and quantitative correlation were found between methods in regard to individual antibodies and their categories (profiles). All assays showed good clinical performance in APS, and strong correlation with APS-related clinical symptoms. Importance of determining individual laboratory 99 percentile values for a healthy population as normal cut-off values was shown. Additionally, based on a clinical approach, this study has established the low/medium threshold for QUANTA Flash aCL IgG and IgM assays.

CONCLUSIONS

This study showed good clinical performance and strong correlation of the new automated CIA aPL assays with APS clinical symptoms. It also enabled us to determine the corresponding low/medium antibody threshold for the aCL antibody methods with different unit types.

Delineating the deranged immune system in the antiphospholipid syndrome

The antiphospholipid syndrome (APS) is a systemic autoimmune disease that is characterized serologically by the presence of antiphospholipid antibodies (aPL) and clinically by vascular thrombosis and obstetric complications. The protein β2 glycoprotein I (β2GPI) is identified as the most important autoantigen in this syndrome. Activation of endothelial cells, thrombocytes and placental tissue by anti-β2GPI antibodies relates to the clinical manifestations of APS. This review describes genetic and environmental factors in relation to APS and summarizes the current knowledge on abnormalities in components of both the innate and adaptive immune system in APS. The role of dendritic cells, T-cells, B-cells, monocytes, neutrophils and NK-cells as well as the complement system in APS are discussed. Several gaps in our knowledge on the pathophysiology of APS are identified and a plea is made for future extensive immune cell profiling by a systems medicine approach in order to better unravel the pathogenesis of APS, to gain more insight in the role of the immune system in APS as well as having the potential to reveal biomarkers or novel therapeutic targets.

The role of the gut microbiota in the pathogenesis of antiphospholipid syndrome

Infectious triggers are associated with the induction of transient antiphospholipid antibodies. One therefore wonders if microbes that permanently colonize us play a role in the pathogenesis of antiphospholipid syndrome (APS). The microbiota represents the collection of all microorganisms colonizing humans and is necessary for normal host physiology. The microbiota, however, is a constant stress on the immune system, which is tasked with recognizing and eliminating pathogenic microbes while tolerating commensal populations. A growing body of literature supports a critical role for the commensal-immune axis in the development of autoimmunity against colonized barriers (e.g., gut or skin) and sterile organs (e.g., pancreas or joints). Whether these interactions affect the development and sustainment of autoreactive CD4(+) T cells and pathogenic autoantibodies in APS is unknown. This review provides an overview of the current understanding of the commensal-immune axis in autoimmunity with a focus on the potential relevance to APS. Additionally, we discuss emerging findings supporting the involvement of the gut microbiota in a spontaneous model of APS, the (NZW × BXSB)F1 hybrid, and formalize hypotheses to explain how interactions between the immune system and the microbiota may influence human APS etiopathogenesis.

Validity of the global anti-phospholipid syndrome score to predict thrombosis: a prospective multicentre cohort study

OBJECTIVE

To investigate the validity of the global APS score (GAPSS) to predict thrombosis in patients with autoimmune diseases.

METHODS

This prospective cohort study included consecutive patients with aPL or SLE. aPL, aPS-PT and GAPSS were determined. A Cox proportional hazards model assessed the validity of GAPSS and identified other potential independent predictors of thrombosis.

RESULTS

One hundred and thirty-seven patients [43.5 (s.d. 15.4) years old; 107 women] were followed up for a mean duration of 43.1 (s.d. 20.7) months. Mean GAPSS was significantly higher in patients who experienced a thrombotic event compared with those without [10.88 (s.d. 5.06) vs 8.15 (s.d. 5.31), respectively, P = 0.038]. In univariate analysis, age [hazard ratio (HR) = 1.04 (95% CI 1.01, 1.08)] and GAPSS above 16 [HR = 6.86 (95% CI 1.90, 24.77)] were each significantly associated with thrombosis during follow-up, while history of arterial thrombosis [HR = 2.61 (95% CI 0.87, 7.82)] failed to reach significance. Among aPL assays, IgG aPS/PT--a component of the GAPSS--was significantly associated with thrombosis [HR = 2.95 (95% CI 1.02, 8.51)]. In multivariate analysis, GAPSS above 16 remained the only significant predictor of thrombosis [HR = 6.17 (95% CI 1.70, 22.40)].

CONCLUSION

This first external validation study confirmed that GAPSS can predict thrombosis in patients with aPL and associated autoimmune diseases.

Antiphospholipid syndrome: antibodies to Domain 1 of β2-glycoprotein 1 correctly classify patients at risk

BACKGROUND

Determination of lupus anticoagulant (LA), anticardiolipin (aCL) and β2-Glycoprotein 1 (aβ2GP1) antibodies is mandatory to classify patients with antiphospholipid syndrome (APS) into risk categories.

OBJECTIVES

To measure relevant antibodies, considered to be those of the IgG isotype directed towards β2GP1 and particularly those directed to Domain 1 (Dm1) of the molecule.

PATIENTS/METHODS

In this cross-sectional study we measured IgG aβ2GP1-Dm1 by a chemiluminescent immunoassay in a group of individuals initially positive for IgG aβ2GP1 and classified as triple (LAC+, IgG aCL+, IgG aβ2GP1+, n = 32), double (LAC-, IgG aCL+, IgG aβ2GP1+, n = 23) or single positive (LA-, IgG aCL-, IgG aβ2GP1+, n = 10).

RESULTS AND CONCLUSION

Geometric mean and standard deviation expressed as chemiluminescent units (CU) in triple, double and single positive groups were 273.0 ± 6.2, 18.2 ± 9.6 and 4.4 ± 2.2, respectively. The geometric mean obtained in 40 healthy subjects was 2.0 ± 2.0. Mean CU values were significantly different among groups and with respect to values found in 40 healthy subjects (P < 0.0001). Positive values of IgG aβ2GP1-Dm1 (above 14.2 CU) were found in 45 individuals while 20 individuals (20/65 = 30.8%) positive for IgG aβ2GP1 were negative for IgG aβ2GPI-Dm1. There was a significant association between positive IgG aβ2GP1-Dm1 and thromboembolic events (P = 0.001). Positive and negative values of IgG aβ2GP1-Dm1 were consistently confirmed after 12 weeks, with only three low positive values being negative after 12 weeks. In conclusion, IgG aβ2GP1-Dm1 seems a robust and reproducible test that in association with the classic tests may be useful in clinical practice in identifying individuals at high risk of developing thromboembolic events.