Antiphospholipid Syndrome Research Articles

Lupus anticoagulant and valvular cardiac surgery.

Despite its name, lupus anticoagulant (LAC) neither exclusively occurs in lupus nor induces anticoagulation. It is an antiphospholipid antibody found in 2%-4% of the population that promotes clot formation by targeting phospholipid-protein complexes in cell membranes. However, in vitro, LAC exhibits paradoxical effects, prolonging clotting times in phospholipid-dependent assays such as Activated Partial Thromboplastin Time (APTT). This unpredictability extends to point-of-care tests like Activated Clotting Time (ACT), which are frequently used to monitor anticoagulation during cardiac surgeries involving cardiopulmonary bypass (CPB). High doses of unfractionated heparin (UFH) are administered in these procedures, but the presence of LAC complicates ACT measurements, creating challenges for both anesthesiologists and surgeons. This case report highlights the clinical implications of LAC in perioperative management, underscoring the difficulties in ensuring adequate anticoagulation during CPB.

The effect of immunosuppressive agent FTY-720 on coagulation, nitroxidergic lung activity and water balance in experimental antiphospholipid syndrome

Antiphospholipid syndrome (APS) is a systemic acquired autoimmune thrombophilia that leads to impaired non-respiratory lung functions due to the circulation of antiphospholipid antibodies, shifting the balance between the coagulation link of hemostasis and the anti-coagulation system towards hypercoagulation. The research examines the modulating effect of FTY-720 on the water balance, coagulation and NO-activity of the lungs under conditions of experimental APS. The functional activity of FTY-720 is largely due to its ability to bind to S1P1 receptors and block signaling pathways mediated by the interaction of the mediator sphingosine-1-phosphate with them. The main effect of FTY-720 is immunosuppression, which develops as a result of the drug’s receptor interaction predominantly with S1P1 receptors, resulting in the retention of autoreactive lymphocytes in lymph nodes, and prevents further spread of inflammation and damage. The experiments were conducted on 85 male rats, divided into groups as follows: The first group of animals (n = 30) was injected with cardiolipin antigen every other day for three weeks for APS modeling; the rats of the second group (n = 25), which served as a control group, were similarly injected with 0.9% NaCl; APS modeling and FTY-720 injection were combined on the remaining animals (n = 30). Three weeks later, arterial (art) and venous (ven) blood was taken, in which APTT and PT were determined using a hemocoagulometer CGL 2110 “Solar” and the corresponding coefficients of APPT of ven/art, PT of ven/ art were calculated. NO-activity was assessed by the content of plasma NO and NO bronchoalveolar lavage obtained by washing the extraction of the bronchopulmonary complex in anesthetized animals. To study the water balance of the lungs, the mass of moist and dried lungs was measured, were determined the total, extra- and intravascular fluid of the lungs. In APS, an increase in APTT and PT of arterial and venous blood was observed, an increase in the level of NO in bronchoalveolar lavages against the background of worsening nitroxidergic activity of the lungs – the NO index of ven/art decreased. There was a positive effect of FTY- 720 on the restoration of non-respiratory lung functions in APS.

Extra-Hepatic Portal Venous Obstruction in Pregnant Women of South-Asian Descent: A Case Series

Liver diseases complicate approximately 3% of pregnancies worldwide, and require specialized care to ensure optimal pregnancy outcomes. Extra-hepatic portal venous obstruction (EHPVO), even though asymptomatic in a majority of the cases, has a higher risk of variceal bleeding in pregnancy and adverse pregnancy outcomes. In this series, we describe five cases of EHPVO presenting during pregnancy at our tertiary care hospital, their antenatal management, and delivery outcomes. In our case series on EHPVO in pregnancy, a majority of the women were diagnosed during childhood and adequately asymptomatic before pregnancy. Two women underwent Endoscopic band ligation for esophageal varices and one woman underwent splenectomy before pregnancy for disease control. One woman was Anti-nuclear antibody (ANA) positive and another was Anti-phospholipid antibody (APLA) positive, while the other three did not have pre-existing thrombotic tendencies. One patient required Endoscopic band ligation during pregnancy. Pregnancy complicated by hypertension was noted in two of the five women (40%). Four of the five women (80%) had thrombocytopenia requiring blood products during delivery. Two women underwent preterm vaginal delivery, and one woman underwent preterm Caesarean section because of placental abruption. Three women had a post-partum hemorrhage, which was effectively managed with uterotonics and blood products. All five women and their neonates were discharged in good health. Multi-disciplinary approach with standardized antenatal care can give positive pregnancy outcomes in women with EHPVO.

Impact of Antiphospholipid Syndrome on Reproductive Outcomes: Current Insights and Management Approaches.

Antiphospholipid syndrome (APS) is a disease characterized by the presence of antiphospholipid (aPL) antibodies, thrombosis, and obstetric complications. While patients with APS can have successful pregnancies, many important considerations exist. APS can also cooccur with other systemic autoimmune diseases which can affect pregnancy, particularly systemic lupus erythematosus. This article reviews specific considerations for pregnancy and reproductive health in patients with APS. Similar to other autoimmune diseases, stable or quiescent disease and planning with a rheumatologist and obstetrician prior to conception are vital components of a successful pregnancy. Pregnancy management for patients with aPL antibodies or diagnosis of APS with aspirin and/or anticoagulation depending on disease profile is discussed, as well as the effects of physiologic changes during pregnancy in maternal and fetal outcomes for this population. Given the reproductive span lasts beyond conception through delivery, we include discussions on safe contraception options, the use of assistive reproductive technology, pregnancy termination, menopause, and male fertility. While APS is a relatively rare condition, the effects this disease can have on maternal and fetal outcomes even with available therapies demonstrates the need for more high-quality, evidence-based research.

Complex antiphospholipid syndrome successfully controlled for 17 years with personalized enoxaparin therapy

Antiphospholipid syndrome (APS) is a systemic autoimmune disease characterized by the presence of antiphospholipid antibodies and venous and arterial thrombotic events, including obstetric complications. We describe the case of a 56-year-old female diagnosed with APS with triple antibody positivity and multiple disease-associated manifestations, namely recurrent purpuric lesions, adrenal insufficiency due to infarction, acalculous cholecystitis, and three spontaneous abortions. Her follow-up was marked by severe thrombotic and haemorrhagic events, notably splanchnic vein thrombosis and haemorrhagic shock after a renal biopsy, as well as the diagnosis of systemic lupus erythematosus 8 years after the APS diagnosis. Chronic anticoagulation with enoxaparin, with dosage guided by anti-factor Xa activity, resulted in stability without complications over 17 years. This case emphasizes the importance of personalized therapeutic strategies and close monitoring in patients with APS.

Recurrent pulmonary thromboembolism with cardiac tamponade as initial manifestations of lupus and antiphospholipid syndrome: a case report

Systemic lupus erythematosus (SLE) is an inflammatory autoimmune disease with an important course due to systemic compromise. SLE is frequently associated with antiphospholipid syndrome, and pulmonary thromboembolism (PE) is particularly common. It is extremely rare for PE to be the initial clinical presentation and even more uncommon for it to coincide with cardiac tamponade, representing a challenge in diagnosis and management. We present a case of a 42-year-old woman with recurrent PE with severe pleural and pericardial effusion, hemodynamic instability, and cardiac tamponade. Laboratory workup revealed hypocomplementemia, leukopenia, negative SLE antibodies, and a positive lupus anticoagulant. This case emphasizes the importance of determining the etiology of PE, assessing risk classification, and implementing proper management, which are crucial for the patient's survival and outcome.

L-arginine, aminoguanidine and mesenchymal stem cells reduce the level of endoplasmic reticulum stress markers and D-dimer in the lungs of mice with antiphospholipid syndrome

Antiphospholipid syndrome (APS) is an autoimmune disease characterized by damage to the intima of the microcirculatory blood vessels as a result of the formation of autoimmune antibodies to phospholipids of cell membranes. Recent data indicate a possible link between the occurrence of autoimmune diseases and endoplasmic reticulum stress, impaired nitric oxide availability, high plasma D-dimer level. The aim of the study was to estimate the effect of nitric oxide synthesis modulators L-arginine and aminoguanidine, and mesenchymal stem cells on the level of inositol-requiring enzyme-1a (IRE-1a), glucose-regulated protein 78 (GRP-78) as ER stress markers, and the level of D-dimer in the lung tissue of female BALB/c line mice with experimental APS induced with cardiolipin administration. 30 experimental animals were divided into five groups: 1 – control animals; 2 – mice with APS; 3 – mice with APS, injected intraperitoneally with L-arginine hydrochloride (25 mg/kg) and aminoguanidine (10 mg/kg); 4 – mice with APS, injected intraperitoneally with stem cells (5×106/kg); 5 – mice with APS, injected with L-arginine hydrochloride, aminoguanidine and stem cells in combination. After 10 days post APS formation animals were removed from the experiment, proteins were extracted from the lung tissue and their level was determined with Western blotting. It was established that in group with APS the levels of IRE-1, GRP-78 and D-dimer were substantially increased as compared to the control group. After separate administration of both arginine with aminoguanidine and MSC, as well as with their combined use, the level of IRE-1, GRP-78 and D-dimer decreased compared to the indices in animals with induced APS. The obtained data indicated that this effect is probably due to the reduction of ER stress through iNOS inhibition and the anti-inflammatory action of MSCs. Keywords: aminoguanidine, antiphospholipid syndrome, D-dimer, endoplasmic reticulume stress, GRP-78, IRE-1, L-arginine, lung, mesenchymal stem cells

Prevalence and clinical value of autoantibodies directed against lysobisphosphatidic acid in antiphospholipid syndrome.

To assess the prevalence and clinical significance of autoantibodies against lysobisphophatidic acid (aLBPA) in patients with antiphospholipid syndrome (APS). We conducted a retrospective analysis involving 91 patients with persistent conventional antiphospholipid antibodies (aPL): 60 patients with at least one clinical event of APS (symptomatic group) and 31 without (asymptomatic group), as well as 33 aPL-negative controls. Detection of aLBPA in serum samples was performed using an enzyme-linked immunosorbent assay (ELISA) specifically designed for this study. The prevalence of aLBPA is significantly higher in patients with persistent aPL than that of the control group (p< 0.0001). Among patients with persistent aPL, our findings reveal a significantly higher prevalence of aLBPA in asymptomatic patients compared with their symptomatic counterparts (p= 0.027). Notably, patients positive for IgG aPL alone demonstrated a greater likelihood of presenting clinical events suggestive of APS. The combined assay of aLBPA and conventional aPL could be used to stratify patients with persistent aPL. This combined approach could serve as a valuable tool in the management of this complex autoimmune disease, particularly in guiding decisions regarding the initiation of primary thromboprophylaxis in asymptomatic patients with persistent aPL.

Teaching NeuroImages: Cilioretinal Artery Occlusion Secondary to Antiphospholipid Syndrome.

Teaching NeuroImages: Cilioretinal Artery Occlusion Secondary to Antiphospholipid Syndrome.

Bilateral Adrenal Hemorrhage in a Patient Anticoagulated with Apixaban for Antiphospholipid Syndrome (APS): A Rare Case Report

Context: Adrenal hemorrhage is a recognized yet rare complication associated with antiphospholipid syndrome (APS), an autoimmune disorder characterized by the presence of antiphospholipid antibodies that increase the risk of thrombosis. The incidence of adrenal hemorrhage in patients with APS has a diagnostic yield of approximately one-third, indicating that it may often go unrecognized in clinical practice. Traditionally, the management of APS has relied on anti-vitamin K therapy, such as warfarin. However, the advent of direct oral anticoagulants (DOACs) has prompted discussions about their use as an alternative. Recent clinical guidelines, however, strongly advise against the use of DOACs in patients with APS due to concerns over their safety and efficacy in preventing thromboembolic events. Case Presentation: This case study describes a 53-year-old woman with a history of venous thromboembolism who was treated with apixaban, a direct oral anticoagulant. She presented with acute abdominal pain and symptoms suggestive of adrenal insufficiency. Initial evaluations revealed significant changes in her clinical condition, leading to further diagnostic imaging. A CT scan demonstrated bilateral adrenal hemorrhage, which was a surprising finding given her anticoagulation therapy. Subsequent laboratory tests indicated a positive triple antibody profile, confirming a diagnosis of primary antiphospholipid syndrome. This case is particularly noteworthy as there have been limited documented instances of adrenal hemorrhage in patients receiving chronic anticoagulation with apixaban. The presentation of bilateral adrenal hemorrhage in the context of APS adds a crucial dimension to the understanding of the disease and its management. Conclusion: This case highlights the potential for serious complications, such as adrenal hemorrhage, in patients with antiphospholipid syndrome, particularly those treated with direct oral anticoagulants. It underscores the necessity for clinicians to remain vigilant for such rare yet significant events in the management of APS. Additionally, this case raises important questions regarding the appropriateness of DOACs in this patient population, especially given the latest recommendations against their use. Increased awareness and further investigation into the implications of anticoagulation strategies in APS patients are warranted to improve patient outcomes and safety.

Antiphospholipid Antibodies as Key Players in Systemic Lupus Erythematosus: The Relationship with Cytokines and Immune Dysregulation.

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by an overproduction of cytokines, such as interleukins and interferons, contributing to systemic inflammation and tissue damage. Antiphospholipid syndrome is a thrombo-inflammatory autoimmune disease affecting a third of SLE patients. We performed an in-depth analysis of the available literature, and we highlighted the complex interplay between immunity, inflammation, and thrombosis, the three major pathogenic pathways that are trapped in a mutually reinforcing destructive loop.

Clinical and immunologic abnormalities in COVID-19

Objective: to find approaches to improve diagnostics of the debut of rheumatic manifestations, associated with COVID-19.Material and methods. Data from 1000 patients from the COVID-19 registry were included in the prospective cohort study. In all patients, the diagnosis of COVID-19 was confirmed by polymerase chain reaction. Of these patients, 380 (41.8% men and 58.2% women, mean age 47.0±2.5 years) had rheumatic manifestations. Patients were examined using routine clinical methods. Immunological markers of rheumatic diseases were determined, including antibodies against cyclic citrullinated peptide, rheumatoid factor, antiphospholipid antibodies and antinuclear factor (ANF), and an immunoblot for antinuclear antibodies was performed if ANF titer was &gt;1:160.Results and discussion. Patients had the following rheumatic manifestations: arthralgias (in 342), myalgias (in 23), skin rashes (in 15). ANF titers &gt;1:160 were found in 57.6% of patients. No reliable data indicating the development of an antiphospholipid syndrome were found in the study group. Lupus anticoagulant was detected in 5.7% of cases, antibodies against β2-glycoprotein in 5.7%, antibodies against cardiolipin in 3.8%. High ANF titers were found in 63.9% of patients with arthralgia. Gender-specific differences were found when analyzing the correlation between ANF titers and rheumatic manifestations: in men, high ANF tires were associated with myalgias, and in women with arthralgias. The presence of rheumatic manifestations depended directly on the severity of the disease. A correlation between arthralgia and leucopenia was also found – leucocyte count &lt; 3,9 ‧109 /L was a predictor of arthralgias. The sensitivity and specificity of the model were 99.3 and 91.2%, respectively.Conclusion. The results suggest that COVID-19 can provoke the development of immunological abnormalities that may subsequently lead to the development of an autoimmune diseases (AID). The optimal approach to prevention and early detection of AID in patients with coronavirus infection caused by SARS-CoV-2 is to monitor laboratory parameters – leukocyte count and CRP level. If rheumatic manifestations are present, the use of immunological and imaging examinations is also recommended.

Pregnancy planning in lupus and APS patients

Systemic Lupus Erythematosus (SLE) and Antiphospholipid Syndrome (APS) have a substantial impact on pregnancy outcomes and require meticulous planning and management. This article explores the complex interrelationships between SLE, APS, and pregnancy and provides an overview of the associated risks and predictors. The crucial role of pre-conception counselling, risk stratification and tailored treatment plans is highlighted, accompanied by a suggested practical approach. Recent advancements in therapeutic approaches and emerging research on promising targeted interventions indicate the potential for enhanced maternal and fetal outcomes.

How to treat patients with thrombotic antiphospholipid syndrome in 2024?

Antiphospholipid syndrome encompasses a range of clinical conditions, particularly thrombotic or obstetrical manifestations, associated with the presence of antiphospholipid antibodies. Managing thrombotic antiphospholipid syndrome in daily clinical practice can be challenging and requires thorough risk stratification and tailored treatment strategies. Primary prophylaxis focuses on improving traditional thrombosis risk factors and, in certain situations, may include low-dose aspirin and / or prophylactic anticoagulants (e.g., low-molecular-weight heparin). The treatment of thrombotic antiphospholipid syndrome primarily involves long-term anticoagulation with vitamin K antagonists. In some cases, a combination of vitamin K antagonists and low-dose aspirin, vitamin K antagonists with international normalized ratio target >3 or a switch to therapeutic doses of low-molecular-weight heparin might be employed. The use of hydroxychloroquine is essential for patients with secondary systemic lupus erythematosus and may be considered for patients with recurrent thrombosis. In other selected situations, the use of immunomodulatory agents can be considered.

Autoantibodies to protein S may explain rare cases of coagulopathy following COVID-19 vaccination.

While Coronavirus disease 2019 (COVID-19) vaccines have proven to be both effective and generally safe, rare but severe adverse events following immunization (AEFIs) are described. Autoantibodies to platelet factor-4 are associated with catastrophic thrombotic AEFIs, but comprehensive investigations of other autoantibodies are lacking. We aimed to detect and describe autoantibodies targeting coagulation-related proteins in a population-wide cohort (SWEDEGENE) including AEFIs attributed to COVID-19 vaccines in Sweden. Subjects were recruited from December 2020 to October 2022 and were stratified based on diagnosis and COVID-19 exposure. Screening was carried out in two phases, with a multiplex bead-based assay in the first subset (until September 2021) and with targeted assays for the second (until October 2022). Positivity was defined based on absolute, relative, and biological/technical thresholds. Patients with coagulation-related AEFIs were older and the Vaxzevria vaccine was overrepresented in this group. Two cases had antiphospholipid antibodies but none had PF4 antibodies. We identified six positives for protein S autoantibodies. Protein S concentrations were negatively correlated with autoantibody response in patients with immunoreactivity and functional analysis revealed low protein S activity in three subjects. Our population-wide analysis reveals cases with autoantibodies against protein S which possibly underlie coagulopathic AEFIs.

ANA-positive versus ANA-negative Antiphospholipid Antibody-positive Patients: Results from the APS ACTION Clinical Database and Repository.

This study focused on the prevalence and impact of antinuclear antibodies (ANA) in antiphospholipid antibody (aPL)-positive patients without concomitant systemic autoimmune rheumatic diseases (SARDs). Data from aPL-positive patients with or without Revised Sapporo APS classification criteria were retrieved from the APS ACTION Registry. Patients with concomitant SARDs were excluded. 430 aPL-positive patients were included in the analysis, 56% ANA-positive and 44% negative. ANA positivity was significantly associated with history of hematologic manifestations (persistent autoimmune hemolytic anaemia, thrombocytopenia, leukopenia and/or lymphopenia) (16% of ANA-positive vs 7% of ANA-negative, p= 0.006). Triple aPL-positivity was more frequent in the ANA-positive subgroup (p= 0.02), along with low baseline C3 and C4 levels (p= 0.05 and p= 0.009, respectively), and higher frequency for extractable nuclear antigens (ENA). Among aPL-positive patients with no APS classification, ANA-positive patients showed a higher rate of arthritis (p= 0.006). Among female patients who have experienced at least one pregnancy, 113 were ANA-positive and 96 were ANA-negative; ANA-negative patients had a higher number of pregnancies (p= 0.018), and number of live births (p= 0.014). A wider proportion of ANA-positive patients were treated with hydroxychloroquine (HCQ) (p< 0.001). When we analysed aPL-positive patients with no other SARDs, ANA status was not associated with thrombosis or pregnancy morbidity. Interestingly, ANA-positive patients showed higher rates of systemic autoimmune features, including hematologic manifestations, multiple aPL positivity, lower complement levels, ENA positivity, and joint involvement, and were more often treated with HCQ. Finally, aPL-positive subjects who were ANA-negative had a higher rate of pregnancies and live births.

Peripheral Ischemia and Necrosis Revealing Buerger&amp;apos;s Disease in an Internal Medicine Department

Buerger&amp;apos;s disease is a systemic vasculitis strongly correlated with tobacco use. It entails a heavy socio-occupational impact. We report the case of a 26-year-old patient with ischemia of the lower limbs revealing Buerger’s disease. He is known smoker with passive exposure to Indian hemp. He was seen for ischemic foot pain that had been progressing for a year. Involvement began in the left big toe. Subsequently, hyperalgesic necrotic lesions were observed on the 3rd, 4th and 5th toes of the foot. Biological investigations revealed an inflammatory syndrome with normocytic anemia and increased C-reactive protein. Retroviral, syphilitic, Hepatitis B and C viruses and SARS-CoV-2 serologies were negative. Antinuclear antibodies were initially borderline at 100 IU with speckled fluorescence, then negative on control. Neutrophil cytoplasmic antibodies and antiphospholipid antibodies were negative. Investigation of thrombophilia was non-contributory, notably factor V mutation testing, antithrombin III assay, proteins C and S and fibrinogen. An arterial ultrasound revealed extensive arterial thrombosis with thickening of the femoral arterial vessel walls. Thromboangiitis obliterans was confirmed and the patient was put on corticosteroids and adjuvant therapy. Surgical treatment was performed 4 months later. Buerger&amp;apos;s disease is a serious vascular disorder which must be diagnosed very early in order to prevent complications. Early smoking cessation leads to remission in the early phase.

Rare connective tissue diseases in patients with C1-inhibitor deficiency hereditary angioedema: first evidence on prevalence and distribution from a large Italian cohort study.

In patients with Hereditary Angioedema (HAE) related to primary C1 inhibitor deficiency (C1INH), the defective clearance of immune complexes and apoptotic materials along with impairment of normal humoral response potentially leads to autoimmunity. Few studies report evidence on autoimmune diseases in C1INH-HAE, but no large population studies focus on rare connective tissue diseases (RCTDs). We aim at evaluating for the first time prevalence and distribution of RCTDs - Systemic Lupus Erytematosus (SLE), primary Sjogren Syndrome (SjS), primary antiphospholipid syndrome (APS), Systemic Sclerosis (SSc), and mixed connective tissue diseases (MCTD) in a large Italian cohort of C1INH-HAE patients. A multicenter observational study includes C1INH-HAE patients from ITACA Centers throughout Italy (time frame Sept 2023-March 2024). Inclusion criteria are i. a defined diagnosis of type I or type II C1INH-HAE; ii. age ≥15 years (puberty already occurred); iii. enrollment in the ITACA Registry. The diagnosis of SLE, primary SjS, primary APS, SSc, and MCTD are made in accordance with international classification criteria. Data are collected from a total of 855 C1INH-HAE patients referring to 15 ITACA Centers. Patients with concomitant RCTDs were 18/855 (2.1%) with F:M ratio 3.5 and a prevalent type I C1INH-HAE diagnosis (87.2%). A diagnosis of SLE results in 44.5% of cases (n=8) while the remaining diagnoses are primary SjS (22.2%, n=4), primary APS (16.6%, n=3), SSc (11.2%, n=2), and a single case of MCTD (5.5%). The female gender is prevalent in all the RCTDs. Patients on long term prophylaxis (LTP) are significantly prevalent in RCTDs group than in the whole C1INH-HAE population (p<0.01). A relevant prevalence of RCTDs is documented in C1INH-HAE patients, mainly SLE. Patients with RCTDs are on LTP in a significant proportion supporting the idea of a bidirectional link between C1INH-HAE and autoimmunity.

Utilizing Artificial Intelligence to Reconcile Indeterminate Lupus Anticoagulant Panel Results

Abstract Lupus anticoagulant (LA) is one laboratory criterion for diagnosing antiphospholipid antibody syndrome (APS), a condition associated with hypercoagulability, pregnancy complications, and death. LA diagnosis requires a complex panel, often performed at a specialized laboratory. Ruling out false positive or transient LAs requires ≥ two positive tests ≥ 12 weeks apart. Most LA tests are negative, with small subsets resulting positive or indeterminate. Indeterminates leave clinicians with limited understanding of appropriate clinical follow-up. Thus, the International Society on Thrombosis and Hemostasis discourages weak resulting nomenclature such as “indeterminate.” Our study used artificial intelligence to predict LA indeterminate results as positive or negative, identifying patients requiring further testing. This IRB approved study reviewed nearly 4000 LA tests performed from 2019-2023. Parameters included CBC, thromboelastography, renal/hepatic function assays, coagulation tests, antiphospholipid antibodies and LA tests. LA test components included screening tests (APTT, Dilute Russel Viper Venom Test (DRVVT) screen), mixing studies (1:1 APTT mix, DRVVT mix), phospholipid-dependent confirmation (DRVVT, hexagonal phase, platelet neutralization), and factor VIII. A positive LA test fulfilled 4 criteria: at least one positive screening test, mixing study and phospholipid-dependent assay and factor VIII inhibitor exclusion. An LA panel meeting 2-3 criteria resulted indeterminate. Studies meeting &amp;lt;2 criteria were negative. This analysis was performed using Machine Intelligence Learning Optimizer (MILO) platform which displays the performance of multiple models. MILO was trained with two classifications: positive and negative cases. Data was split into training (100 training positives; 100 negatives) and testing (primary and secondary validation) sets (100 positives; 1388 negatives). LA panels affected by drug interactions (9.4%) or containing incomplete datasets (21%) were excluded. Sensitivity, specificity, negative predictive value (NPV) and positive predictive value (PPV) determined model efficacy. 2903 negative (84%), 318 positive (9.1%), and 246 indeterminate (7.1%) LA results were included from 3467 patients. Only 84 of the 246 indeterminate patients (34%) were retested. Of these, 28 remained indeterminate, 43 became negative and 13 resulted positive. The best performing MILO models were the K-nearest neighbor (KNN) and logistic regression. The ability of these models to determine which indeterminate cases would become positive or negative was evaluated. KNN displayed the highest specificity (0.88) and PPV (0.57). All models had a high NPV and specificity due to substantive exposure to negative cases for the training and testing. Exclusion of some parameters did not improve the performance of the models. However, even the best model (various KNN models) had low sensitivity and PPV due to a small pool of positive training/testing cases and a much smaller group of indeterminate LA with subsequent positive results. Creating models accurately predicting indeterminate cases that may become positive enables appropriate clinical follow-up. Thus, improving model accuracy will require a larger sample size of positive indeterminates with follow-up.

A Tale of Two Cases: Acquired Hemophilia A and/or Lupus Anticoagulant?

Abstract Distinguishing between acquired hemophilia A (AHA) and lupus anticoagulant (LA) is essential for effective clinical management. This can be challenging due to similarities in laboratory tests and potential interference between their diagnostic tests. Here we present two complex cases. Case 1 is a 69-year-old female with PNH presenting with a subdural hematoma. Prolonged aPTT with no correction on mixing raised clinical suspicion of AHA. Factor VIII activity was low (2%) across three dilutions in the factor assay. A Bethesda assay revealed a low factor VIII inhibitor (1%). LA was negative by DRVVT. Antiphospholipid antibodies (Cardiolipin and Beta-2-Glycoprotein 1) were also negative. Treatment with prednisone and intravenous immunoglobulin was initiated with presumptive diagnosis of AHA. Subsequent samples to check other factor levels uncovered low Factor IX as well. Higher dilutions in factor assays exhibited non-parallelism in Factor IX and VIII, suggesting a non-specific inhibitor. Chromogenic Factor VIII was within the normal range. Another LA test, Staclot-LA was positive. Overall, this case was consistent with LA rather than AHA. The initial ‘positive’ Bethesda assay was attributed to interference by LA. Case 2 is a 20-year-old female with no significant medical history who was admitted elsewhere for a complicated C-section with intraabdominal hemorrhage. She had prolonged aPTT and positive LA by platelet neutralization test there. Upon transfer, the initial assessment confirmed prolonged aPTT and a time-dependent inhibitor pattern in mixing studies. Factor studies revealed significantly diminished factor VIII activity (&amp;lt;1%) using both one-stage clotting and chromogenic assays. A strong factor VIII inhibitor was identified through chromogenic Bethesda assay (126 BU). Non-parallelism was observed in other factors (Factor IX, XI, XII). LA was negative by DRVVT but positive by Staclot-LA. Cardiolipin and beta2-glycoprotein-1 antibodies were negative. The diagnosis of AHA was evident. But is there concurrent LA present? Both Staclot-LA and platelet neutralization tests are PTT-based and susceptible to interference from factor VIII inhibitor. The patient underwent treatment, and factor VIII inhibitor disappeared in 3 months. Staclot-LA also turned negative, suggesting that the initially ‘positive’ LA test was likely a result of interference. In both cases, adopting a holistic approach to differentiate between AHA and LA is beneficial. Relying solely on individual tests may lead to false interpretations, as LA can inhibit FVIII activity assays and produce false positives in the Bethesda assay. It is advisable to include higher dilutions in factor assays and/or chromogenic assays to mitigate interference. The presence of factor VIII inhibitor can also result in false-positive LA results such as Staclot-LA assay. For more reliable results, DRVVT and antibody tests are preferable. If the aPTT-based assay is the sole positive LA test, the presence of LA is suggested when it occurs before and/or after the presence of a factor inhibitor.