Antiphospholipid patterns predict risk of thrombosis in systemic lupus erythematosus.

OBJECTIVE: We evaluated which aPL combinations increase the risk of future thrombosis in patients with SLE. METHODS: This prospective cohort study consisted of SLE patients who had been tested for all seven aPL (LA, aCL isotypes IgM, IgG and IgA, and anti-ß2-glycoprotein I isotypes IgM, IgG and IgA). Pooled logistic regression was used to assess the relationship between aPL and thrombosis. RESULTS: There were 821 SLE patients with a total of 75 048 person-months of follow-up. During the follow-up we observed 88 incident cases of thrombosis: 48 patients with arterial, 37 with venous and 3 with both arterial and venous thrombosis. In individual models, LA was the most predictive of any [age-adjusted rate ratio 3.56 (95% CI 2.01, 6.30), P < 0.0001], venous [4.89 (2.25, 10.64), P < 0.0001] and arterial [3.14 (1.41, 6.97), P = 0.005] thrombosis. Anti-ß2-glycoprotein I IgA positivity was a significant risk factor for any [2.00 (1.22, 3.3), P = 0.0065] and venous [2.8 (1.42, 5.51), P = 0.0029] thrombosis. Only anti-ß2-glycoprotein I IgA appeared to add significant risk to any [1.73 (1.04, 2.88), P = 0.0362] and venous [2.27 (1.13, 4.59), P = 0.0218] thrombosis among those with LA. We created an interaction model with four categories based on combinations of LA and other aPL to look at the relationships between combinations and the risk of thrombosis. In this model LA remained the best predictor of thrombosis. CONCLUSION: Our study demonstrated that in SLE, LA remained the best predictor of thrombosis and adding additional aPL did not add to the risk, with the exception of anti-ß2-glycoprotein I IgA.

Cutaneous manifestations of antiphospholipid syndrome.

Antiphospholipid syndrome (APS) is an acquired thrombophilic disorder in which autoantibodies are produced against a variety of phospholipids and phospholipid-binding proteins. The purpose of this article is to review cutaneous findings in patients with APS diagnosis. An overview regarding prevalence, description, pathogenesis and histopathology, are described for cutaneous manifestations of APS.

The Role of Antiphospholipid Antibodies in COVID-19.

PURPOSE OF THE REVIEW: Elevated levels of anti-phospholipid (aPL) antibodies are the most important criterion in the diagnosis of anti-phospholipid syndrome (APS) and are usually responsible for promoting the risk of thrombotic complications. Now, in the course of the global coronavirus disease 2019 (COVID-19) pandemic, measurable aPL antibodies have also been detected in a noticeable number of patients showing a variety ranging from studies with only isolated positive tests to cohorts with very high positivity. Thus, the question arises as to whether these two different clinical pictures may be linked. RECENT FINDINGS: The ambivalent results showed a frequent occurrence of the investigated aPL antibodies in COVID-19 patients to an individually varying degree. While some question a substantial correlation according to their results, a number of studies raise questions about the significance of a correlation of aPL antibodies in COVID-19 patients. Within the scope of this review, these have now been described and compared with each other. Ultimately, it is necessary to conduct further studies that specifically test aPL antibodies in a larger context in order to make subsequent important statements about the role of APS in COVID-19 and to further strengthen the significance of the described comparisons.

Systematic Review of Antiphospholipid Antibodies in COVID-19 Patients: Culprits or Bystanders?

PURPOSE OF REVIEW: COVID-19 patients have a procoagulant state with a high prevalence of thrombotic events. The hypothesis of an involvement of antiphospholipid antibodies (aPL) has been suggested by several reports. Here, we reviewed 48 studies investigating aPL in COVID-19 patients. RECENT FINDINGS: Prevalence of Lupus Anticoagulant (LA) ranged from 35% to 92% in ICU patients. Anti-cardiolipin (aCL) IgG and IgM were found in up to 52% and up to 40% of patients respectively. Anti-ß2-glycoprotein I (aß2-GPI) IgG and IgM were found in up to 39% and up to 34% of patients respectively. Between 1% and 12% of patients had a triple positive aPL profile. There was a high prevalence of aß2-GPI and aCL IgA isotype. Two cohort studies found few persistent LA but more persistent solid phase assay aPL over time. aPL determination and their potential role is a real challenge for the treatment of this disease.

Anti-phosphatidyl-serine/prothrombin antibodies (aPS/PT) in isolated lupus anticoagulant (LA): is their presence linked to dual test positivity?

OBJECTIVES: Anti phosphatidylserine/prothrombin antibodies (aPS/PT) are often present in patients with antiphospholipid syndrome (APS) and might be relevant in the pathogenesis of this condition. They are major determinant of lupus anticoagulant (LA) in triple-positive antiphospholipid (aPL) profile. Whether they are present and pathogenic in patients with isolated LA [negative anticardiolipin (aCL) and anti ß2-glycoprotein I (aß2GPI) antibodies] is a matter of debate. METHODS: We measured aPS/PT in a large number of isolated LA with the aim to ascertain whether there is a link between the way isolated LA is assessed and the presence of these antibodies. APS/PT were measured in 86 patients with isolated LA (aCL- and abeta2GPI-). LA was assessed by two test systems, the dilute Russell Viper Venom Time (dRVVT) and the Silica Clotting Time (SCT). RESULTS: Sixty-six (77%) individuals with isolated LA were positive for aPS/PT (IgM 44, IgG and IgM 15, IgG in 7). Diagnosis of LA was made based on positive results in both dRVVT and SCT in 40 patients (Group 1) and based on only one positive test in the remaining 46 patients (Group 2). The rate of positive aPS/PT antibodies was significantly higher in Group 1 (OR=7.2, 95% CI 1.9-27.0, p<0.002). Moreover, the titre of IgM aPS/PT was significantly increased in Group 1 as compared to Group 2 (137 U, IQR 64-179 vs. 43 U, IQR 11-120, p=0.008). CONCLUSIONS: These data indicate an association between LA based on two positive coagulation tests and the presence of aPS/PT antibodies, especially of IgM isotype.

Therapeutic plasma exchange for anticoagulant-refractory antiphospholipid syndrome with severe ischemic and necrotic skin lesions: A case series.

Antiphospholipid syndrome (APS) is a systemic autoimmune disease characterized by clinical findings including thrombosis and/or obstetric complication and laboratory findings, e.g. ≥1 positive antiphospholipid antibodies (aPL) (lupus anticoagulant, anticardiolipin IgG/IgM and/or anti-ß2-glycoprotein IgG/IgM). A rare APS clinical entity is severe necrosis which is difficult to treat and often does not respond to anticoagulant therapy. Three consecutive patients with primary or secondary APS who presented with necrotic skin lesions secondary to APS were treated with therapeutic plasma exchange (TPE), glucocorticoids and low-molecular-weight heparin. All patients had a rapid-onset, either full or significant recovery of their APS-related necrotic lesions. Upon treatment, one patients showed resolution of lupus anticoagulant. Two patients had a decrease of at least 88 % in aPL titers after the initial treatment, and were kept on TPE maintenance every 5-6 weeks. None of the patients experienced significant side effects of the TPE. This is the first case series showing the clinical benefits of TPE in patients with ischemic and necrotic skin lesions due to severe anticoagulant-refractory vascular APS.

Interest of IgG and IgM antiprothrombin autoantibodies in the exploration of antiphospholipid syndrome: a 5-year retrospective study.

OBJECTIVES: Non-conventional aPL have been described in patients presenting clinical manifestations of antiphospholipid syndrome but negative for conventional markers. Among them, detection of autoantibodies against prothrombin has been proposed to improve diagnosis and management of these patients. However autoantibodies against prothrombin are heterogeneous and their use in clinical practice still remains unclear. The aim of this study was to evaluate the interest of IgG and IgM autoantibodies directed against the prothrombin only (aPT). METHODS: We retrospectively studied IgM and IgG aPT results, conventional antiphospholipid syndrome markers and clinical data of a large cohort of 441 patients referred for antiphospholipid syndrome exploration with aPT detection over a period of 5 years. RESULTS: We observed a total prevalence of 17% of aPT-positive patients (75/441). A significant association was found between aPT and thrombosis (P = 0.035), with 70% of patients having unexplained thrombosis, aPT representing the sole aPL detected. aPT positivity was significantly more frequent in venous thrombosis than in arterial thrombosis (P = 0.004). Interestingly, we demonstrated for the first time that aPT IgG levels were higher in recurrent thrombosis than in isolated thrombosis (P = 0.013), leading us to propose a predictive level of recurrence for thrombosis. CONCLUSION: Our results show that aPT are associated with thrombosis and demonstrate the interest of assessing both IgG and IgM aPT, in particular in venous thrombosis when conventional markers are negative. Quantification of aPT could predict recurrence of thrombosis and influence subsequent treatment strategy. Prospective clinical studies are now required to confirm these results.

Autoimmune and rheumatic musculoskeletal diseases as a consequence of SARS-CoV-2 infection and its treatment.

The coronavirus disease-2019 (COVID-19) pandemic is likely to pose new challenges to the rheumatology community in the near and distant future. Some of the challenges, like the severity of COVID-19 among patients on immunosuppressive agents, are predictable and are being evaluated with great care and effort across the globe. A few others, such as atypical manifestations of COVID-19 mimicking rheumatic musculoskeletal diseases (RMDs) are being reported. Like in many other viral infections, severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection can potentially lead to an array of rheumatological and autoimmune manifestations by molecular mimicry (cross-reacting epitope between the virus and the host), bystander killing (virus-specific CD8 + T cells migrating to the target tissues and exerting cytotoxicity), epitope spreading, viral persistence (polyclonal activation due to the constant presence of viral antigens driving immune-mediated injury) and formation of neutrophil extracellular traps. In addition, the myriad of antiviral drugs presently being tried in the treatment of COVID-19 can result in several rheumatic musculoskeletal adverse effects. In this review, we have addressed the possible spectrum and mechanisms of various autoimmune and rheumatic musculoskeletal manifestations that can be precipitated by COVID-19 infection, its therapy, and the preventive strategies to contain the infection.

Domain I of ß2GPI is capable of blocking serum IgA antiphospholipid antibodies binding in vitro: an effect enhanced by PEGylation.

OBJECTIVES: This study aims to inhibit antiphospholipid syndrome (APS) serum derived IgA anti-beta-2-glycoprotein I (aß2GPI) binding using Domain I (DI). METHODS: Serum from 13 APS patients was tested for IgA aß2GPI and Anti-Domain I. Whole IgA was purified by peptide M affinity chromatography from positive serum samples. Serum was tested for IgA aß2GPI binding in the presence and absence of either DI or of two biochemically modified variants containing either 20 kDa of poly(ethylene glycol) (PEG) or 40 kDa of PEG. RESULTS: Significant inhibition with DI was possible with average inhibition of 23% (N = 13). Further inhibitions using 20 kDa PEG-DI and 40 kDa PEG-DI variants showed significant inhibition (p = 0.0001) with both the 40 kDa PEG-DI and 20 kDa PEG-DI variants showing increased inhibition compared with DI alone (p = 0.0001 and p = 0.001, n = 10). CONCLUSIONS: Inhibition of IgA aß2GPI by DI is possible and can be enhanced by biochemical modification in a subset of patients.

Autoimmune haemolytic anaemia and thrombocytopaenia in a single-centre cohort of patients with systemic lupus erythematosus from Turkey: clinical associations and effect on disease damage and survival.

INTRODUCTION: Thrombocytopaenia and autoimmune haemolytic anaemia (AIHA) have considerable impact on prognosis in systemic lupus erythematosus (SLE). We investigated the frequencies of these haemocytopaenias, along with their associations and effect on outcome in a single-centre cohort of patients with SLE. METHODS: Demographic characteristics, clinical features, autoantibody profiles, damage and mortality data were compared between patients with and without each haematological abnormality. Variables displaying significant differences between the groups were entered into logistic regression. RESULTS: Ninety-three patients had AIHA and 215 had thrombocytopaenia. Both were associated with neuropsychiatric (NP) involvement, with each other, leucopaenia, antiphospholipid syndrome (APS) and antiphospholipid antibodies. More patients in both groups had organ damage, and their damage scores were higher. Association to NP damage was discernible. In addition, cardiovascular and renal damage and diabetes were more pronounced in patients with thrombocytopaenia. At logistic regression analysis, younger age, anticardiolipin antibody IgM positivity, leucopaenia and thrombocytopaenia were associated with AIHA whilst lupus anticoagulant activity, AIHA, leucopaenia, APS and NP involvement were associated with thrombocytopaenia. Among damage items, peripheral vascular damage, diabetes, NP damage, renal and ocular damage displayed significant associations with thrombocytopaenia, whereas none of the items did with AIHA. Patients with AIHA had significantly reduced survival rates at 10 and 20 years. CONCLUSIONS: We observed that AIHA and thrombocytopaenia were associated with severe lupus, affecting major organs and causing end organ damage. Thus, they may be considered as prognostic markers. Furthermore, AIHA and especially thrombocytopaenia may also be a marker for a subgroup of lupus patients who have or may develop APS.

Thrombophilia in non-thrombotic chronic venous disease of the lower limb - a systematic review.

Chronic venous disease (CVD) represents a significant healthcare burden. Thrombophilia is proposed as a risk factor, particularly for post-thrombotic CVD. A systematic review was performed to determine the relationship between thrombophilia and non-thrombotic CVD. MEDLINE® and Embase® databases were searched from 1946 up to March 2018. Case-control studies, cohort studies or randomised clinical trials reporting on thrombophilias in non-thrombotic lower limb CVD in adult patients were included. Non-English and post-thrombotic syndrome studies were excluded. Study selection and data extraction were performed by two reviewers. Fifteen studies were included, reporting on 916 cases and 1261 controls. Studies largely focused on venous ulceration and investigated multiple haemostatic factors. An association between thrombophilia and non-thrombotic CVD was identified, with greater prevalence and factor concentration alteration reported in patients compared to controls. Concomitant thrombophilia presence was associated with earlier CVD onset. Relationship strength varied, with commoner aetiologies showing clearer correlation than rarer ones. Thrombophilia is associated with non-thrombotic CVD but the mechanism is unclear and causation cannot be determined. Future research should focus on prospective studies with larger populations and identify adjunct therapies targeting thrombophilia.

The Lupus Anticoagulant Paradox.

Lupus anticoagulant (LA) represents the most enigmatic antibody population in patients with antiphospholipid syndrome and represents a paradox that is still unsolved. This class of antiphospholipid antibody causes a phospholipid-dependent prolongation of the clotting time but is associated with an increased risk of thrombosis and pregnancy morbidity. In this review, we will provide an overview of the different antibodies that have been associated with LA activity, their importance based on clinical studies, and address the question why this prolongation of the clotting time is associated with thrombosis rather than a bleeding tendency.

Distinguishing lupus anticoagulants from factor VIII inhibitors in haemophilic and non-haemophilic patients.

INTRODUCTION: Accurate diagnosis of an inhibitor, a neutralizing antibody to infused factor VIII (FVIII), is essential for appropriate management of haemophilia A (HA). Low-titre inhibitors may be difficult to diagnose due to high rates of false-positive inhibitor results in that range. Transient low-titre inhibitors and false-positive inhibitors may be due to the presence of a lupus anticoagulant (LA) or other non-specific antibodies. Fluorescence immunoassay (FLI) to detect antibodies to FVIII is a sensitive method to identify inhibitors in HA. Evaluations of antibody profiles by various groups have demonstrated that haemophilic inhibitors detected by Nijmegen-Bethesda (NBA) and chromogenic Bethesda (CBA) assays correlate with positivity for anti-FVIII immunoglobulin (Ig) G1 and G4. AIM: This study sought to determine whether FLI could distinguish false-positive FVIII inhibitor results related to LAs from clinically relevant FVIII inhibitors in HA patients. METHODS: Samples from haemophilic and non-haemophilic subjects were tested for LA, specific FVIII inhibitors by NBA and CBA, and anti-FVIII immunoglobulin profiles by FLI. RESULTS: No samples from LA-positive non-haemophilic subjects were positive by FLI for anti-FVIII IgG4. Conversely, 91% of NBA-positive samples from haemophilia subjects were positive for anti-FVIII IgG4. Two of 11 haemophilia subjects had samples negative for anti-FVIII IgG4 and CBA, which likely represented LA rather than FVIII inhibitor presence. CONCLUSIONS: Assessment of anti-FVIII profiles along with the CBA may be useful to distinguish a clinically relevant low-titre FVIII inhibitor from a transient LA in HA patients.

Direct oral anticoagulants: an alternative treatment for thrombotic antiphospholipid syndrome?

Background Direct oral anticoagulants (DOACs) demonstrate a lower risk-benefit ratio than vitamin K antagonists (VKAs) for secondary thromboprophylaxis of thrombotic events. But there are no data on the efficacy of DOACs for the prevention of thrombotic recurrence in patients with antiphospholipid syndrome (APS). In this study, we evaluated the efficacy of DOACs to prevent recurrences of thrombotic events in patients with APS. Methods This was a single-center pilot, using a multi-step Fleming design. If seven or fewer patients presented treatment failure with rivaroxaban, the study could conclude efficacy. Results A total of 23 patients were included. APS involved the veins only ( n = 19), arteries only ( n = 2) or both ( n = 1) and 1 patient exhibited catastrophic antiphospholipid syndrome (CAPS). Overall, two patients were positive for lupus anticoagulant, anti-beta-2 glycoprotein I antibodies and anticardiolipid antibodies (triple positivity). The mean duration of follow up was 35.6 (range, 29-40) months. A total of six treatment failures were reported: one patient, with triple positivity, developed bilateral distal pulmonary embolism (PE) after 20 months of treatment with rivaroxaban, two patients refused to take rivaroxaban, the treatment was stopped in three other patients: two with adverse effects and one with chronic iron-deficiency anemia. Conclusions Rivaroxaban may represent an alternative for secondary thromboprophylaxis for thrombo-embolism in patients with APS, in particular, those with poor international normalized ratio (INR) control and those who are not at the highest risk of recurrent thrombosis, such as those with triple positivity.

Lupus Anticoagulant-hypoprothrombinemia Syndrome (LAC-HPS) in Children With Systemic Lupus Erythematosus: Report of 3 Cases.

Lupus anticoagulant, also known as lupus antibody, is generally associated with thrombosis rather than bleeding events. Lupus anticoagulant-hypoprothrombinemia syndrome in children is rather rare but can lead to mild to life-threatening bleeding. Here, we report 3 cases of lupus anticoagulant-hypoprothrombinemia syndrome associated with systemic lupus erythematosus. They initially presented with mucocutaneous bleedings, and subsequently developed other symptoms fulfilling the laboratory criteria for systemic lupus erythematosus. Case 2 and 3 had significant epistaxis and intracerebral hemorrhage responded to systemic corticosteroid along with fresh frozen plasma. Three cases demonstrated acquired hypoprothrombinemia with no correction of mixing studies. Case 1 had low factor X level, which has never been reported previously. In all 3 cases, their coagulogram returned to normal level after corticosteroid treatment.

Non-Criteria or Seronegative Obstetric Antiphospholipid Syndrome?

BACKGROUND: Obstetric antiphospholipid syndrome (Obs-APS) is one of the most commonly identified causes of recurrent pregnancy loss and its accurate diagnosis is a requirement for optimal treatment. Some patients do not fulfill the revised Sapporo classification criteria, the original APS classification criteria, and are considered to be non-criteria Obs-APS. In these patients with non-criteria, there is controversy about their inclusion within the spectrum of APS and eventually their treatment as having Obs-APS. A subset of patients may also have clinical characteristics of Obs-APS even though lupus anticoagulant (LA), anticardiolipin antibodies, and anti-ß2-glycoprotein I (aß2GPI) antibodies are consistently negative. These patients are recognized as seronegative Obs-APS. We reviewed evidence of non-criteria Obs-APS and discuss a case of a woman with a diagnosis of active systemic lupus erythematosus (SLE) and non-criteria Obs-APS with four consecutive pregnancy losses. After an accurate diagnosis the patient received prenatal counseling and benefited from the optimal treatment of Obs-APS that led to a successful pregnancy. The applicability of this successful experience about outcomes in women with non-criteria, or seronegative, Obs-APS is also evaluated.

Assessment of the underlying causes of the immune thrombocytopenia: Ten years experience.

OBJECTIVE: Immune thrombocytopenia (ITP) is an immune haematologic disorder causing platelet destruction mediated by anti-platelet antibodies. In this study we aimed to evaluate the clinical and laboratory variables of ITP patients in southeast of Turkey. METHODS: In this retrospective study 167 ITP patients between 2005 and 2015 were evaluated. All patients were screened for immunological parameters including ANA (antinuclear antibodies), anti dsDNA (anti-double-stranded-DNA), ACA(anti-cardiolipin) IgM and IgG, LA (lupus anticoagulants). All patients were screened for Helicobacter pylori, HBsAg (Hepatitis B surface antigen), anti-HCV (hepatitis C virus antibody), and anti-HIV ½ (HIV antibody) and brucellosis.. RESULTS: Among the patients, 50 (29.9%) patients were male, 117 (70.1%) were female. The age range of patients was 18-86 (mean 38.16±14). In 56 patients (33.5%) splenectomy was performed. 36 patients (21.6%) were positive for ANA, 5 (3%) were positive for anti dsDNA, 14 (8.4%) for ACA Ig G, and 14 (8.4%) patients for ACA IgM. LA was tested in 165 patients and 30 (18%) patients were positive for LA. Microbiologic evaluation was as follows: 16 patients (9.6%) were positive for HbsAg, 109 (65.3%) positive for Anti-HBs, 5 positive for anti-HCV (3%), 56 (33.5%) patients were positive for Helicobacter pylori antigen, 5 (2.9%) for Brucella and one patient was positive for anti-HIV ½. CONCLUSIONS: Immune thrombocytopenia patients have to be evaluated according to their demographic characteristics and laboratory results. Secondary causes of ITP were HIV, HCV, Helicobacter pylori, brucellosis, tuberculosis, and autoimmune diseases in our region. Management of ITP patients can change in different regions.

Women's Issues in Antiphospholipid Syndrome.

BACKGROUND: Antiphospholipid syndrome (APS) is an autoimmune systemic disease characterized by vascular thrombosis (arterial or venous) and/or pregnancy complications associated with the occurrence of autoantibodies, specifically lupus anticoagulant, anticardiolipin antibodies, and/or anti-ß2 glycoprotein-I antibodies confirmed at least twice over a 12 week period according to the 2006 Sydney criteria. Antiphospholipid antibodies are encountered  in the general population with a reported prevalence of 1% to 5%  However, APS is far more infrequent with a prevalence of 40-50/100,000 persons and an incidence of about 5 new patients/100,000 persons. APS can be diagnosed in patients with no apparent clinical or laboratory pathology (primary APS) or it may be related to numerous other conditions, autoimmune diseases (usually systemic lupus erythematosus), malignancies, infections and drugs (secondary APS). Women are at risk for APS since the disease is encountered in both the primary and the secondary state in females more often than in men. In addition, women in their reproductive years can develop APS (either classical or obstetric), and special attention is warranted in pregnant women with a diagnosis of APS. The benefits of hormonal therapy in the form of contraception or hormone replacement treatment should be carefully weighed against the increased risk for vascular complications in women with APS.

Cerebral Venous Sinus Thrombosis in A Patient with Sjögren's Syndrome with Atypical Antibodies: A Case Report.

BACKGROUND: Although Sjögren's syndrome has been known to complicate with white matter lesions, encephalopathy, or stroke, reports of cerebral venous sinus thrombosis due to Sjögren's syndrome with atypical antibodies are rare. CASE REPORT: A 50-year-old woman was admitted to our neurological ward with nausea and vomiting following acute onset of severe headache in the left occipital region. Brain computed tomography revealed no abnormalities. The patient was fully conscious, with normal cognitive functioning, but exhibited unsteady tandem gait. Both magnetic resonance venography and computed tomography venography suggested left transverse sinus blockage. Intravenous enoxaparin, followed by oral warfarin, was initiated as treatment for cerebral venous sinus thrombosis. After investigation, Sjögren's syndrome was diagnosed and lupus anticoagulant antibody test was positive. The patient was treated with hydroxychloroquine, and appeared fully recovered at the 6-month follow-up, with no clinical or radiological signs of relapse. CONCLUSION: This case reports the relationship between cerebral venous sinus thrombosis and Sjögren's syndrome. It is necessary to screen autoimmune disorders in patients with cerebral venous sinus thrombosis that present with no common risk factors of venous thrombosis in order to prevent inappropriate management, and potentially adverse outcomes.

Laboratory evaluation of anti-phospholipid syndrome: a preliminary prospective study of phosphatidylserine/prothrombin antibodies in an at-risk patient cohort.

Immunoglobulin (Ig)G/IgM autoantibodies to phosphatidylserine/prothrombin (aPS/PT) were evaluated individually and in combination with criteria anti-phospholipid (aPL) tests in a prospectively ascertained cohort of patients at risk for anti-phospholipid syndrome (APS). One hundred and sixty (160) consecutive requests for lupus anti-coagulant (LAC) from the University of Utah Health Sciences Center were identified during 8 weeks. Of these, 104 unique patients had additional requests for cardiolipin (aCL) and/or beta2 glycoprotein I (aß2 GPI) IgG and/or IgM; samples were retained and analysed for aPS/PT, aCL and/or aß2 GPI IgG and IgM antibodies. Following testing, a comprehensive chart review was performed and patients categorized according to their clinical diagnosis. Individual and combined sensitivities, specificities, odd ratios (OR), diagnostic accuracy for specific tests or combinations by receiver operating characteristic (ROC), area under the curve (AUC) analyses and correlations between test results were determined. The sensitivities of aPS/PT IgG/IgM (54·6/45·5%) were lower than LAC (81·8%) but higher relative to aCL IgG/IgM (27·3/0%) or aß2 GPI IgG/IgM (27·3/0%). The best correlation between LAC and any aPL test was observed with aPS/PT (P = 0·002). There was no significant difference in the diagnostic accuracies for any panel with LAC: LAC/aß2 GPI IgG/aCL IgG [AUC 0·979, OR 475·4, 95% confidence interval (CI) 23·1-9056·5, P = 0·0001 and LAC/aß2 GPI IgG/aPS/PT IgG or LAC/aPS/PT IgG/aCL IgG (AUC 0·962, OR 265·3, 14·2-4958·2, P = 0·0001). The high correlation between LAC and aPS/PT IgG/IgM in this preliminary study suggest that this marker may be useful in the evaluation of APS. More studies to determine the optimal aPL antibody tests combination are needed.