Predictive value of persistent versus transient antiphospholipid antibody subtypes for the risk of thrombotic events in pediatric patients with systemic lupus erythematosus

Antiphospholipid Antibodies Occurrence in Acute SARS-CoV-2 Infection without Overt Thrombosis

We sought to determine the prevalence of antiphospholipid antibodies (aPLs) and their correlation with COVID-19 severity (in terms of clinical and laboratory parameters) in patients without thrombotic events during the early phase of infection. This was a cross-sectional study with the inclusion of hospitalized COVID-19 patients from a single department during the COVID-19 pandemic (April 2020-May 2021). Previous known immune disease or thrombophilia along with long-term anticoagulation and patients with overt arterial or venous thrombosis during SARS-CoV-2 infection were excluded. In all cases, data on four criteria for aPL were collected, namely lupus anticoagulant (LA), IgM and IgG anticardiolipin antibodies (aCL), as well as IgG anti-β2 glycoprotein I antibodies (aβ2GPI). One hundred and seventy-nine COVID-19 patients were included, with a mean age of 59.6 (14.5) years and a sex ratio of 0.8 male: female. LA was positive in 41.9%, while it was strongly positive in 4.5%; aCL IgM was found in 9.5%, aCL IgG in 4.5%, and aβ2GPI IgG in 1.7% of the sera tested. Clinical correlation: LA was more frequently expressed in severe COVID-19 cases than in moderate or mild cases (p = 0.027). Laboratory correlation: In univariate analysis, LA levels were correlated with D-dimer (p = 0.016), aPTT (p = 0.001), ferritin (p = 0.012), C-reactive protein (CRP) (p = 0.027), lymphocyte (p = 0.040), and platelet (p < 0.001) counts. However, in the multivariate analysis, only the CRP levels correlated with LA positivity: OR (95% CI) 1.008 (1.001-1.016), p = 0.042. LA was the most common aPL identified in the acute phase of COVID-19 and was correlated with infection severity in patients without overt thrombosis.

COVID-19 and the antiphospholipid syndrome

Coronavirus disease 2019 (COVID-19) has resulted in a global pandemic. Most COVID-19 patients are asymptomatic or have flu-like symptoms. However, around 15% of the patients may have severe disease, including unilateral or bilateral pneumonia with acute respiratory distress syndrome and progressive hypoxemia that may require mechanical ventilation assistance. A systemic inflammatory response syndrome occurs in the most severe forms of COVID-19, with multiorgan involvement which can be life threatening caused by a cytokine storm. Although what best characterizes COVID-19 are the manifestations of the respiratory system, it has been shown that it also acts at the cardiovascular level, producing coagulation abnormalities, which causes thrombotic events mainly in the arteries/arterioles, microcirculation and venous system, and potentially increased mortality risk. This multiorgan vascular disease overlaps with other known microangiopathies, such as thrombotic microangiopathy or paroxysmal nocturnal hemoglobinuria, where complement overactivation plays an important role in the pathophysiology of thrombosis. Furthermore, coagulopathy secondary to COVID-19 occurs in the context of an uncontrolled inflammatory response, reminiscent of APS, especially in its catastrophic form. This review summarizes the current knowledge regarding the relationship between COVID-19 and the APS.

COVID-19 coagulopathy and antiphospholipid syndrome

The presence of thrombotic events in COVID-19 patients has been described since the beginning of the pandemic. This association has been confirmed in most of the reported studies. Autopsy reports have shown that most thromboses are located in the lung, although they have also been observed in other organs such as the skin and kidneys. SARS-CoV2 infection induces a generalized prothrombotic state, which is attributed to a combination of factors such as hypoxia, excess cellular apoptosis, and mainly to overactivation of the immune system. Among immune-mediated prothrombotic situations, antiphospholipid syndrome (APS) stands out. Recurrent thrombotic events are observed in APS in the presence of antiphospholipid antibodies (aPL). There are numerous studies that report high prevalence of aPL in patients with COVID-19 infection. However, the results show discrepancies in the data on the prevalence of aPL, and its role in the pathogenesis of thrombosis in these patients. This could be due to the heterogeneity of the detection procedures for aPL or to transient elevations of non-pathogenic aPL levels in the context of infection. In this review we try to clarify the role of aPL in COVID-19 infection, and attempt to answer the question of whether it is a coagulopathy of its own, or secondary to APS.

Antigens and Antibodies of the Antiphospholipid Syndrome as New Allies in the Pathogenesis of COVID-19 Coagulopathy

High prevalence of both criteria and extra-criteria antiphospholipid antibodies (aPL) has been reported in COVID-19 patients. However, the differences in aPL prevalence decreased when an age-matched control group was included. The association of aPL with thrombotic events in COVID-19 is very heterogeneous. This could be influenced by the fact that most of the studies carried out were conducted on small populations enriched with elderly patients in which aPL was measured only at a single point and they were performed with non-standardized assays. The few studies that confirmed aPL in a second measurement showed that aPL levels hardly changed, with the exception of the lupus anticoagulant that commonly reduced. COVID-19 coagulopathy is an aPL-independent phenomenon closely associated with the onset of the disease. Thrombosis occurs later in patients with aPL presence, which is likely an additional prothrombotic factor. B2-glycoprotein deficiency (mainly aPL antigen caused both by low production and consumption) is very common during the SARS-CoV2 infection and has been associated with a greater predisposition to COVID-19 complications. This could be a new prothrombotic mechanism that may be caused by the blockage of its physiological functions, the anticoagulant state being the most important.

Antiphospholipid antibodies in patients with myocardial infarction with and without obstructive coronary arteries

BACKGROUND

Recent studies demonstrate that prothrombotic antiphospholipid antibodies (aPL) are overrepresented in patients with myocardial infarction (MI) due to coronary artery disease (MICAD). However, it is not known whether aPL differ between the two subsets of MI: MICAD and MI with nonobstructive coronary arteries (MINOCA).

OBJECTIVES

To determine whether aPL are associated with MINOCA or MICAD, or with hypercoagulability as assessed by activated protein C-protein C inhibitor (APC-PCI) complex.

METHODS

Well-characterized patients with MINOCA (n = 98), age- and gender-matched patients with MICAD (n = 99), and healthy controls (n = 100) were included in a cross-sectional case-control study. Autoantibodies (IgA/G/M) targeting cardiolipin and β₂ glycoprotein-I and specific nuclear antigens were analyzed by multiplexed bead technology. The concentration of APC-PCI was determined as a measure of hypercoagulability by an immunofluorometric sandwich assay.

RESULTS

Both prevalence and titers of aPL of the IgG isotype (anti-cardiolipin and/or anti-β₂ glycoprotein-I) were higher in patients with MINOCA and MICAD than in controls. aPL IgG positivity was twice as frequent among patients with MICAD than MINOCA (11% vs. 6%, nonsignificant). We observed no group differences regarding aPL IgA/M or antibodies targeting specific nuclear antigens. Levels of APC-PCI were elevated in aPL IgG-positive compared to aPL IgG-negative MICAD patients.

CONCLUSIONS

aPL IgG, but not IgA/M, are enriched particularly in patients with MICAD but also in patients with MINOCA, as compared to controls. Interestingly, signs of hypercoagulability-measured by increased levels of the APC-PCI complex-were present in aPL IgG-positive MICAD patients, indicating an association with functional disturbances of the coagulation system.

Managing Antiphospholipid Syndrome in Children and Adolescents: Current and Future Prospects

Pediatric antiphospholipid syndrome (APS) is a rare acquired multisystem autoimmune thromboinflammatory condition characterized by thrombotic and non-thrombotic clinical manifestations. APS in children and adolescents typically presents with large-vessel thrombosis, thrombotic microangiopathy, and, rarely, obstetric morbidity. Non-thrombotic clinical manifestations are frequently seen in pediatric APS and may be present even before the vascular thrombotic events occur. We review insights into the pathogenesis of APS and discuss potential targets for therapy. The identification of multiple immunologic abnormalities in patients with APS reveals molecular targets for current or future treatment. Management strategies, especially for APS in adolescents, require screening for additional prothrombotic risk factors and consideration of counseling regarding contraceptive strategies, lifestyle recommendations, treatment adherence, and mental health issues associated with this autoimmune thrombophilia. The main goal of therapy in pediatric APS is the prevention of thrombosis. The management of acute thrombosis events in children and adolescents is the same as for primary APS, which involves isolated occurrences, and secondary APS, which is seen in association with another autoimmune disease, e.g., systemic lupus erythematosus. A pediatric hematologist should be consulted so other differential thrombophilic conditions can be eliminated. Therapy includes unfractionated heparin or low-molecular-weight heparin followed by vitamin K antagonists. Treatment of catastrophic APS involves triple therapy (anticoagulation, intravenous corticosteroid pulse therapy, and plasma exchange) and may include intravenous immunoglobulin for children and adolescents with this condition. New drugs such as eculizumab and sirolimus seem to be promising drugs for APS.

Evaluation of Frequency, Clinical Correlation, and Antibodies Confirmation Profile in Patients with Suspected Antiphospholipid Syndrome

Antiphospholipid syndrome (APS) is a systemic autoimmune disease characterized by arterial and venous thrombotic manifestations and/or pregnancy-related complications in patients with persistent antiphospholipid (aPL) antibodies. The introduction of Sapporo's classification criteria allowed uniformity in the classification of this pathology, representing a considerable advance in its diagnosis. However, currently some doubts about the application of these criteria still persist. The aim of this study was to contribute to the better understanding of APS by the assessment of aPL prevalence, the association between clinical and laboratory tests, and evaluation of the aPL confirmatory profile.

In this study, 1,179 samples from patients with suspected APS of both genders, without age restrictions, who were advised to test for complete aPL's profile were analyzed. The samples were tested for lupus anticoagulant (LAC), anticardiolipin immunoglobulin (Ig) G/IgM and anti-β-2-glycoprotein I IgG/IgM antibodies. Patient samples with isolated test requests for analysis and samples from patients under the influence of anticoagulants or in an infectious process were excluded.

The overall positivity found was 17.9% and the most frequent aPL was LAC. The antibodies were determined in isolation and in association. The prevalence of triple positivity was 0.8% and double positivity was 1.8%. Positivity was higher in inpatient/emergency services compared with outpatient services. There was a higher positivity in individuals over 41 years, males, patients with systemic lupus erythematosus, kidney complications, and deep vein thrombosis/thrombophlebitis. The positivity confirmation with second sample was 39.5% and the confirmation profile shows that 50.6% of samples confirmed with same positivity profile; 17.3% with a different profile and regarding to these, 2.5% of the samples confirmed positivity with a different antibody from the previously detected.

This study suggests that the aPL's positivity tends to increase with age, showing that the aPL's testing should be avoided during an acute event and reinforces the need for complete aPL laboratory profile in the second sample and subsequent determinations.

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-β2-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-β2-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-β2-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-β2-glycoprotein I IgA.

Childhood-onset systemic lupus erythematosus-related antiphospholipid syndrome: A multicenter study with 1519 patients

OBJECTIVE

To assess childhood-onset systemic lupus erythematosus-related antiphospholipid syndrome(cSLE-APS) in a large Brazilian population.

METHODS

A retrospective observational cohort study was carried-out in 27 Pediatric Rheumatology university centers, including 1519 cSLE patients.

RESULTS

cSLE-APS was observed in 67/1519 (4%) and was diagnosed at disease onset in 39/67 (58%). The median disease duration was 4.9 (0-17) years. Thrombosis recurrences were evidenced in 18/67 (27%) cSLE-APS patients. The most frequent thrombosis sites in cSLE-APS patients were: venous thrombosis in 40/67 (60%), especially deep vein thrombosis in 29/40 (72%); arterial thrombosis in 35/67 (52%), particularly stroke; small vessels thrombosis in 9/67 (13%) and mixed thrombosis in 3/67 (4%). Pregnancy morbidity was observed in 1/67 (1%). Non-thrombotic manifestation associated to cSLE-APS occurred in 21/67 (31%), mainly livedo reticularis in 14/67 (21%), valvar thickening in 4/67 (6%) and valvar vegetations not related to infections in 2/67 (3%). None of them had catastrophic APS. Further analysis demonstrated that the median of SLICC/ACR-DI [1(0-5) vs. 0(0-7),p < 0.0001] was significantly higher in cSLE-APS patients compared to cSLE without APS. The frequencies of cerebrovascular disease (40% vs. 1%,p < 0.0001), polyneuropathy (9% vs. 1%,p < 0.0001), SLICC/ACR-DI ≥1 (57% vs. 27%, p < 0.0001) and intravenous cyclophosphamide use (59% vs. 37%, p < 0.0001) were significantly higher in the former group.

CONCLUSIONS

Our large multicenter study demonstrated that cSLE-APS was a rare condition, occurring during disease course with a high accrual damage. Central and peripheral neuropsychiatric involvements were distinctive features of this autoimmune thrombosis.

Significance of Anti-Phosphatidylethanolamine Antibodies in the Pathogenesis of Recurrent Pregnancy Loss

Anti-phosphatidylethanolamine antibody (aPE), an anti-phospholipid autoantibody (aPL), has been proposed as a factor in recurrent pregnancy loss (RPL). However, conflicting views exist on the pathogenicity of RPL, and aPE has not yet been included in the classification criteria for antiphospholipid syndrome (APS). Here, we aimed to determine the clinical importance of examining aPE. aPE (IgG, IgM) was measured in 1705 patients with a history of RPL and re-examined after a 12-week interval in patients who tested positive. Persistent positive patients were administered low-dose aspirin during the subsequent pregnancy and clinical outcomes depending on the presence, type, and persistence of aPE were evaluated. Among the patients positive for aPE IgG and aPE IgM in the first examination (n = 117; 6.87%, and n = 235; 13.6%, respectively), 31.5% and 37.6% were negative upon re-examination, respectively. Moreover, among the cases with known pregnancy outcome, the miscarriage rate in the cumulative positive aPE group was 32.6% (29/89), which did not differ significantly from that of the aPE negative group (27.7%; 80/209; P = 0.178). Alternatively, the miscarriage rate in the persistently positive group was 40.7% (22/54), which was significantly higher than that in the transient positive group, 20.0% (7/35) (P = 0.041). Particularly, this difference become more significant when focusing on aPE IgM, 46.9% (15/32) in the persistent, compared with 16.7% (4/24) in the transient positive group (P = 0.024). aPE IgM is suggested to serve as a pathogenic aPL together with anti-cardiolipin antibodies and lupus anticoagulants, particularly if these factors persist over an extended period of time.

Pediatric APS: State of the Art

PURPOSE OF REVIEW

The purpose of this report is to review recent research findings on APS in children and neonates.

RECENT FINDINGS

European evidence-based recommendations for diagnosis and treatment of pediatric APS has recently been published by the SHARE Initiative. Recent studies have shown a high prevalence of non-thrombotic manifestations in children with aPL, domains 4/5 specificity of 'innocent' anti-β2GPI antibodies in infants, and a higher risk for developmental delays and learning disabilities, hence, the need for neurodevelopmental monitoring in children born to mothers with APS. An International effort on creating a new diagnostic criteria for APS is underway. Pediatric APS is a rare disease with significant differences from the APS in adults. Majority of the children with persistently positive aPL do not develop thrombotic events; however, relatively higher proportion of thrombosis in children is related to aPL positivity compared to adults; this may partly be due to the absence of common pro-thrombotic "second-hit" risk factors of adults such as atherosclerosis and cigarette smoking. Diagnosis of APS in children may be delayed or missed when adult APS criteria are used, because in pediatric APS, non-thrombotic clinical manifestations such as thrombocytopenia, hemolytic anemia, and neurological disorders such as migraine, epilepsy, and chorea may precede thrombotic manifestations. Around 20% of the children initially diagnosed with primary APS eventually develop SLE. Neonatal APS is rare; however, the offspring of mothers with APS are at a higher risk for developmental delays and learning disabilities; prematurity and IUGR may increase this risk. Regular assessment of neurodevelopmental status of these children should be performed. Thrombosis is a rare event in the offspring of mothers with APS; anticoagulation of such infants is not recommended. An international effort to create a new diagnostic criteria for APS is underway.

Antiphospholipid antibodies in patients with dysglycaemia: A neglected cardiovascular risk factor?

BACKGROUND

Cardiovascular disease is a serious complication in patients with dysglycaemia, defined as either type 2 diabetes or impaired glucose tolerance. Research focusing on the identification of potential markers for atherothrombotic disease in these subjects is warranted. The antiphospholipid syndrome is a common acquired prothrombotic condition, defined by a combination of thrombotic events and/or obstetric morbidity and positivity of specific antiphospholipid antibodies. Available information on antiphospholipid antibodies in dysglycaemia is scarce.

OBJECTIVE

This study investigates the association between antiphospholipid antibodies and dysglycaemia.

PATIENTS/METHODS

The PAROKRANK (periodontitis and its relation to coronary artery disease) study included 805 patients, investigated 6-10 weeks after a first myocardial infarction, and 805 matched controls. Participants without known diabetes (91%) underwent an oral glucose tolerance test. Associations between antiphospholipid antibodies (anti-cardiolipin and anti-β2 glycoprotein-I IgG, IgM and IgA) and dysglycaemia were analysed.

RESULTS

In total, 137 (9%) subjects had previously known type 2 diabetes and 371 (23%) newly diagnosed dysglycaemia. Compared with the normoglycaemic participants, those with dysglycaemia had a higher proportion with first myocardial infarction (61% vs 45%, p < 0.0001) and were more often antiphospholipid antibody IgG positive (8% vs 5%; p = 0.013). HbA1c, fasting glucose and 2-h glucose were significantly associated to antiphospholipid antibody IgG. Odds ratios (ORs) were 1.04 (95% confidence interval [CI] 1.02-1.06), 1.14 (95% CI 1.00 - 1.27) and 1.12 (95% CI 1.04 - 1.21), respectively, after adjustments for age, gender and smoking.

CONCLUSIONS

This study reports an association between antiphospholipid antibody IgG positivity and dysglycaemia. Further studies are needed to verify these findings and to investigate if antithrombotic therapy reduces vascular complications in antiphospholipid antibody positive subjects with dysglycaemia.

Pediatric antiphospholipid syndrome

Despite its potential to cause significant morbidity in children, pediatric antiphospholipid syndrome (APS) is an understudied condition. In this review, we will cover what is known about pediatric APS epidemiology and how the clinician might approach the diagnosis of pediatric APS. We will highlight similarities and differences with the adult disease, both for primary APS and in the context of lupus. Clinical manifestations beyond thrombosis, especially neurologic and hematologic in nature, will be discussed. We will also consider what unique implications antiphospholipid antibody-positivity may have for children with lupus and for neonates born to mothers with APS. The approach to treatment will be covered, including the unique impact of APS medications on children as compared with adults. Finally, the importance of future mechanistic research is emphasized as physicians endeavor to provide the personalized care that children with APS clearly deserve.

Phospholipid inhibitors

The antiphospholipid syndrome (APS) is defined by the association of arterial and/or venous thrombosis and/or pregnancy complications with the presence of at least one among the main antiphospholipid antibodies (aPL) (i. e., Lupus anticoagulants, LA, IgG and/ or IgM anticardiolipin antibodies, aCL, IgG and/or IgM antiβ2-glycoprotein I antibodies, aβ2-GPI). Several clinical studies have consistently reported that LA is a stronger risk factor for both arterial and venous thrombosis compared to aCL and aβ2-GPI. In particular, LA activity dependent on the first domain of β2-GPI and triple aPL positivity are associated with the risk of thrombosis and obstetrical complications.

Asymptomatic aPL-positive subjects do not require primary thromboprophylaxis. Venous thromboembolism is the most common initial clinical manifestation of APS. To prevent its recurrence indefinite anticoagulation is recommended. Long duration treatment with warfarin or aspirin is used after a first cerebral arterial thrombosis. Low molecular weight heparin (LMWH) with or without aspirin is recommended to reduce the rate of obstetrical complications of APS pregnant women.

Subsequent Thrombotic Outcomes in Patients with Ischemic Stroke with Antiphospholipid Antibody Positivity

PURPOSE

International consensus criteria for antiphospholipid syndrome (APS) require persistently positive antiphospholipid antibodies (aPL) and medium or high titers in association with clinical manifestations. However, the clinical relevance of persistence and titers of aPL in patients with stroke has not been identified. We aimed to investigate the risk of subsequent thrombotic events in patients with ischemic stroke with aPL positivity in terms of aPL status.

MATERIALS AND METHODS

We reviewed the medical records of 99 patients with ischemic stroke with at least one or more aPL-positivity (i.e., positivity for aCL, anti-β2-glycoprotein-1, and/or lupus anticoagulants). The patients were divided into two groups: "definite APS" who fulfilled the laboratory criteria and "indefinite APS" who fell short of the criteria. We compared the risk of subsequent thrombotic events between the two groups. Cox proportional hazards model and Kaplan-Meier survival curves were used for the analyses.

RESULTS

Of the 99 patients, 46 (46%) were classified as having definite APS and 53 (54%) as having indefinite APS. The mean follow-up was 51.6 months. Overall event numbers were 14 (30.4%) in definite APS and 16 (30.2%) in indefinite APS. Increased subsequent thrombotic events (hazard ratio 1.039; 95% confidence interval 0.449-2.404; p=0.930) and decreased time to thrombotic events (log-rank p=0.321) were not associated with aPL status.

CONCLUSION

There was no increased risk of subsequent thrombotic events in ischemic stroke patients with definite APS, compared with those with indefinite APS.

Antiphospholipid syndrome and recurrent miscarriage: A systematic review and meta-analysis

Antiphospholipid syndrome (APS) is an autoimmune condition that is associated with thrombosis and morbidity in pregnancy. The exact mechanisms by which these associations occur appear to be heterogeneous and are not yet well understood. The aim of this study was to identify and analyze publications in recent years to better understand the diagnosis and its contribution to monitoring APS among women with recurrent miscarriage (RM). This systematic review and meta-analysis was conducted using the PubMed and Web of Knowledge databases, with articles published between 2010 and 2014, according to the PRISMA statement. Of the 85 identified studies, nine were selected. Most of the studies reported an association between recurrent miscarriage and specific antiphospholipid antibodies, as anticardiolipin antibodies (aCL), lupus anticoagulant (LA), anti-β2-glycoprotein I antibodies (aβ2GPI) and antiphosphatidylserine (aPS), which showed a relationship with RM. The main result of the meta-analysis revealed association between antiphospholipid antibodies (aPLs) and/or APS compared to the patients with RM (OR: 0.279; 95% CI: 0.212-0.366) and APS cases compared to the patients with RM (OR: 0.083; 95% CI: 0.036-0.189). High heterogeneity among these studies (I²=100.0%, p <0.001) was observed. In addition, there was no significant publication bias across studies according to Begg's test (p=0.230), although Egger's test (p=0.037) suggests significant publication bias. The funnel plot was slightly asymmetrical. Systematic review and meta-analysis demonstrated a positive association between antiphospholipid antibodies and/or antiphospholipid syndrome in patients with recurrent miscarriage.

Thrombophilia and assisted reproduction technology-any detrimental impact or unnecessary overuse?

PURPOSE

The aim of this study is to provide an overview of the studies investigating a possible association between thrombophilia and assisted reproductive technology (ART) outcome.

METHODS

This is a literature review.

RESULTS

Congenital thrombophilias (CoT) are reported to be associated with pregnancy loss. However, the association between CoT and early pregnancy loss is weak and does not necessarily support causation. CoT are more likely to be associated with late fetal loss. Even though data pooled from case-control and cohort studies suggest an increased risk of ART failure in women with CoTs, there seems no association when the analysis is confined to better quality cohort studies. The evidence supporting anticoagulation to improve ART outcome in CoT carriers is weak. Likewise, studies on antiphospholipid antibodies (APAs) and ART outcome suffer from multiple methodological limitations and a detrimental impact of APA positivity is controversial. Empirical administration of heparin or low molecular weight heparin to women with recurrent ART failures is supported by weak evidence. Importantly, thrombophilias are likely to increase thrombotic complications after ovarian stimulation for ART.

CONCLUSIONS

Current evidence does not support routinely testing for or treatment of thrombophilia in the setting of ART nor in couples with implantation failure. A careful personal and family history should be obtained and a risk assessment for thrombotic complications should be made in every woman undergoing ovarian stimulation. If positive, testing for thrombophilia is warranted.

Clinical Application of Revised Laboratory Classification Criteria for Antiphospholipid Antibody Syndrome: Is the Follow-Up Interval of 12 Weeks Instead of 6 Weeks Significantly Useful?

Background. According to revised classification criteria of true antiphospholipid antibody syndrome, at least one of three antiphospholipid antibodies should be present on two or more occasions at least 12 weeks apart. However, it can be inconvenient to perform follow-up tests with interval of 12 weeks. We investigated clinical application of follow-up tests with interval of 12 weeks. Method. Totals of 67, 199, and 332 patients tested positive initially for the lupus anticoagulants confirm, the anti-β 2 glycoprotein-I antibody, and the anti-cardiolipin antibody test, respectively, from Jan 2007 to Jul 2009. We investigated clinical symptoms of patients, follow-up interval, and results of each test. Results. Among patients with initial test positive, 1.5%-8.5% were subjected to follow-up tests at interval of more than 12 weeks. Among 25 patients with negative conversion in tests, patients with interval of more than 12 weeks showed clinical symptom positivity of 33.3%, which was higher than that of 12.5% with 6-12 weeks. Among 34 patients with persistent test positive, clinical symptoms positivity trended to be more evident in patients at interval of 6-12 weeks (47.4% versus 26.7%, P = 0.191) than more than 12 weeks. Conclusion. Less than 10% of patients with initial test positive had follow-up tests at interval of more than 12 weeks and the patients with persistent test positive at interval of more than 12 weeks showed trends toward having lower clinical symptoms than 6-12 weeks. More research is needed focused on the evidence that follow-up test at interval of more than 12 weeks should be performed instead of 6 weeks.

IgG/IgM antiphospholipid antibodies present in the classification criteria for the antiphospholipid syndrome: a critical review of their association with thrombosis

Essentials The clinical value of IgM antibodies in thrombotic antiphospholipid syndrome (APS) is debated. By review of literature, we reconsidered the clinical value of IgM antibodies in thrombotic APS. More significant correlations with thrombosis were found for the IgG compared to IgM isotype. Unavailability of paired IgG/IgM results hampers evaluating the added value of IgM positivity. Click to hear Dr de Groot's perspective on antiphospholipid syndrome

SUMMARY

Background Despite the update of the classification criteria for the antiphospholipid syndrome (APS), difficulties persist in the identification of patients at risk for thrombosis. Current guidelines include assays detecting IgG/IgM anti-β2 -glycoprotein I and anti-cardiolipin antibodies, although the relevance of IgM antibodies has been debated. Objectives Through a review of the literature from 2001 to 2014, we aimed to formally establish the thrombotic risk stratification potential of IgM as compared with IgG anti-phospholipid antibodies (aPLs). Patients/methods One thousand two hundred and twenty-eight articles were selected by a computer-assisted search of the literature. Of the 177 studies that met our inclusion criteria, the clinical value of IgG/IgM aPLs was established through analysis of odds ratios for thrombosis or percentage of positives in the thrombotic population. Results/conclusions We clearly found more significant correlations with thrombosis for the IgG than for the IgM isotype. Nonetheless, in a minority of studies, significant associations with thrombosis were found for IgM but not IgG antibodies. The unavailability of paired results of IgG and IgM for each separate patient hampers evaluation of the added value of isolated IgM positivity. To fully take advantage of results obtained by future studies, we strongly encourage scientists to provide all studied information per patient. We planned a large multicenter study to investigate clinical associations of isolated/combined positivity for criteria/non-criteria aPLs. Importantly, because of the presence of non-pathogenic aPLs, quantitative assays are characterized by a high false-positivity rate. Optimization of functional assays, such as thrombin generation measuring the whole scheme of coagulation, may help to reduce APS-related morbidity and mortality.

Transiently positive anticardiolipin antibodies and risk of thrombosis in patients with systemic lupus erythematosus

Fluctuations in the titers of anticardiolipin antibodies (aCL) have been reported in systemic lupus erythematosus (SLE) patients, but their relation with thrombosis is not completely understood. Prospective inception cohort of 237 patients with SLE (American College of Rheumatology criteria). Positivity for antiphospholipid antibodies (aPL) was defined according to Sapporo criteria. aCL was defined as persistently positive when more than two-thirds of the determinations were positive during follow-up. Patients were classified into four groups: A [positive lupus anticoagulant (LA)], B (negative LA and persistently positive aCL), C (negative LA and transiently positive aCL) and D (negative LA and aCL). Of these 237 patients, 211 (89%) patients were women. Median age at diagnosis and follow-up were 32 (2—78) and 10 (1—31) years, respectively; 33 (13.9%), 23 (9.7%), 42 (17.7%) and 139 (58.6%) patients were classified in groups A, B, C and D, respectively. Thirty (12.6%) and 23 (9.7%) patients suffered arterial and venous thrombotic events, respectively. Adjusted risk for arterial thrombosis was increased in groups A [odds ratio (OR) 15.69, 95% confidential interval (CI) 4.79—51.42, P < 0.001] and B (OR 7.63, 95% CI 2.00—29.08, P = 0.003), but not in group C when compared with group D. Adjusted risk of venous thrombosis was increased in group A (OR 4.24, 95% CI 1.36—13.20, P = 0.013), but not in groups B or C when compared with group D. Risk of thrombosis is not increased in SLE patients with negative LA and transiently positive aCL, even fulfilling Sapporo laboratory criteria, when compared with aPL-negative SLE patients. Lupus (2007) 16, 810—816.

Autoantibodies and their Judicious Use in Pediatric Rheumatology Practice

Autoantibody testing forms an important part of diagnostic workup of patients in Pediatric rheumatology practice. However it is important to understand that the mere presence of autoantibodies does not necessarily mean the presence of an underlying autoimmune disease. Autoantibodies may be present decades before the development of clinical manifestations of an autoimmune disease and may be viewed as harbingers of Autoimmune disease. On the other hand, low-affinity autoantibodies may be present in normal healthy individuals; these natural autoantibodies serve an important function in immune regulation and tolerance. Autoantibody testing in pediatric practice mainly includes testing for anti-nuclear antibodies, anti-dsDNA antibodies, anti-neutrophil cytoplasmic autoantibodies and antiphospholipid antibodies. Rheumatoid factor and anti-CCP do not have much significance in the diagnostic schema in pediatric rheumatology, except perhaps for classification of juvenile idiopathic arthritis (JIA) and prognostication in late-onset polyarticular JIA. The positive predictive value (PPV) of any laboratory test depends on the prevalence of the disease in the population being tested. Hence, test ordering practices greatly impact the performance characteristics and positive predictive value of any laboratory test. A restricted test ordering only in patients with clinical signs and symptoms suggestive of autoimmune disease would thus greatly increase the PPV of tests such as antinuclear antibody used for diagnosing autoimmunity.

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.

Antiphospholipid antibodies correlate with stroke severity and outcome in patients with antiphospholipid syndrome

BACKGROUND

Our goal was to analyze the association of the level of antiphospholipid antibodies (aPLs) with stroke severity and outcome in patients with antiphospholipid syndrome (APS).

METHODS

Observational study included consecutive patients with ischemic stroke younger than 55 years (2007-2012). We analyzed serum levels of aPLs, including anticardiolipin (aCL) antibodies, anti-β2-glycoprotein I antibodies (anti-β2GPI) and antiprothrombin antibodies (aPS/PT) within the first 48 h after admission, and again, in the case of a positive result, at least 12 weeks after the first measurement. Stroke severity was measured by the National Institutes of Health Stroke Scale (NIHSS), and the three-month stroke outcome by the modified Rankin Scale (mRS). Multiple linear regression models were used to analyze the correlation between the aPLs and stroke severity and outcome.

RESULTS

Overall 255 stroke patients were included, 22 (8.6%) with APS. Among them, a positive correlation was found between immunoglobulin M (IgM) aCL levels within 48 h and NIHSS (rho = 0.471; p = 0.027), as well as a tendency toward a positive correlation between immunoglobulin G (IgG) anti-β2GPI levels within 48 h and three-month mRS (rho = 0.364; p = 0.096). Multiple linear regression analyses showed a positive correlation between levels of IgM aCL < 48 h and the NIHSS (β-coefficient [standard error; SE] = 0.127 [0.044]), as well as the levels of IgG anti-β2GPIwithin 48 h and the three-month mRS (β-coefficient [SE] = 0.034 [0.011]).

CONCLUSIONS

In young stroke patients with APS, serum levels of IgM aCL within 48 h are correlated with stroke severity and levels of IgG anti-β2GPI within 48 h are correlated with three-month outcomes.

Assessment and reporting of the clinical immunogenicity of therapeutic proteins and peptides-harmonized terminology and tactical recommendations

Immunogenicity is a significant concern for biologic drugs as it can affect both safety and efficacy. To date, the descriptions of product immunogenicity have varied not only due to different degrees of understanding of product immunogenicity at the time of licensing but also due to an evolving lexicon that has generated some confusion in the field. In recent years, there has been growing consensus regarding the data needed to assess product immunogenicity. Harmonization of the strategy for the elucidation of product immunogenicity by drug developers, as well as the use of defined common terminology, can benefit medical practitioners, health regulatory agencies, and ultimately the patients. Clearly, understanding the incidence, kinetics and magnitude of anti-drug antibody (ADA), its neutralizing ability, cross-reactivity with endogenous molecules or other marketed biologic drugs, and related clinical impact may enhance clinical management of patients treated with biologic drugs. To that end, the authors present terms and definitions for describing and analyzing clinical immunogenicity data and suggest approaches to data presentation, emphasizing associations of ADA development with pharmacokinetics, efficacy, and safety that are necessary to assess the clinical relevance of immunogenicity.

Treatment of the antiphospholipid syndrome

The antiphospholipid syndrome is characterized by a combination of laboratory findings (i.e., the presence of at least one antiphospholipid antibody) and clinical manifestations (arterial and/or venous thrombosis, obstetrical complications). Long-term oral anticoagulant is recommended to prevent recurrence of both arterial and venous thrombosis, whereas (low molecular weight) heparin plus aspirin is the treatment of choice to prevent further obstetrical complications. In the rare case of catastrophic antiphospholipid syndrome, heparin plus high-dose corticosteroids plus plasma exchange is associated with the highest recovery rate. Some new, non-antithrombotic-based treatments of antiphospholipid syndrome with rituximab, autologous stem cell transplantation, or hydroxychloroquine are also reviewed.

Annexin A5 anticoagulant activity in children with systemic lupus erythematosus and the association with antibodies to domain I of β2-glycoprotein I

Children with systemic lupus erythematosus (SLE) have a high prevalence of antiphospholipid (aPL) antibodies and are at increased risk for aPL-related thrombosis. We investigated the association between annexin A5 anticoagulant activity and antibodies to the domain I portion of β2-glycoprotein I (anti-DI antibodies), and propose a potential mechanism for the pathogenesis of aPL-related thrombosis. Using samples from 183 children with SLE collected during the Atherosclerosis Prevention in Pediatric Lupus Erythematosus (APPLE) trial, we examined resistance to the anticoagulant effects of annexin A5, using the annexin A5 resistance (A5R) assay, and evaluated for anti-DI IgG antibodies. Children with SLE had higher frequency of anti-D1 antibodies (p = 0.014) and significantly reduced A5R compared to pediatric controls: mean A5R = 172 ± 30% versus 242 ± 32% (p < 0.0001). Children with SLE and positive anti-DI antibodies had significantly lower mean A5R levels compared to those with negative anti-DI antibodies: mean A5R = 155 ± 24% versus 177 ± 30% (p < 0.0001). In multivariate analysis, anti-DI antibodies (p = 0.013) and lupus anticoagulant (LA) (p = 0.036) were both independently associated with reduced A5R. Children with SLE have significantly reduced annexin A5 anticoagulant activity that is associated with the presence of LA and anti-DI antibodies.

Clinical causes and treatment of the thrombotic storm

Thrombotic storm represents an extreme prothrombotic phenotype, characterized by multiple thrombotic events affecting diverse vascular beds occurring over a brief period of time. Thrombotic events involve venous and arterial circulation, including unusual locations, such as cerebral sinus venous thrombosis, intra-abdominal thromboembolic occlusions and microvascular events. Some patients will have antiphospholipid antibodies, but a significant number have no identifiable hypercoagulable state. The mainstay of treatment consists of anticoagulant therapy, although some patients appear to benefit from the addition of immunomodulatory therapies. Other disorders that share this thrombotic storm phenotype include catastrophic antiphospholipid syndrome, spontaneous heparin-induced thrombocytopenia and similar aggressive clinical disorders. Ongoing studies are focused on identifying underlying genetic factors that may predispose patients to develop this extreme clinical phenotype.

Correct laboratory approach to APS diagnosis and monitoring

Triple positivity (positive Lupus Anticoagulant, anticardiolipin and anti β2-glycoptrotein I antibodies) identifies the pathogenic autoantibody (anti Domain I of β2-glycoptroteinI) that is present in patients with definite Antiphospholipid Syndrome (APS). This is supported by the fact that aβ2GPI antibodies obtained by affinity purification in these patients possess LA activity. Moreover, patients and carriers of this profile carry a much higher risk of thrombosis and pregnancy loss than APS patients with positivity for only one of the tests. Thus, very different risk categories exist among patients with APS as well as among carriers of aPL. Clinical studies and interventional trials should first take these high risk subjects into consideration.

Antiphospholipid syndrome: laboratory testing and diagnostic strategies

The antiphospholipid syndrome (APS) is diagnosed in patients with recurrent thromboembolic events and/or pregnancy loss in the presence of persistent laboratory evidence for antiphospholipid antibodies. Diagnostic tests for the detection of antiphospholipid antibodies include laboratory assays that detect anticardiolipin antibodies, lupus anticoagulants, and anti-β(2)-glycoprotein I antibodies. These assays have their origins beginning >60 years ago, with the identification of the biologic false positive test for syphilis, the observation of "circulating anticoagulants" in certain patients with systemic lupus erythematosus, the identification of cardiolipin as a key component in the serologic test for syphilis, and the recognition and characterization of a "cofactor" for antibody binding to phospholipids. Although these assays have been used clinically for many years, there are still problems with the accurate diagnosis of patients with this syndrome. For example, lupus anticoagulant testing can be difficult to interpret in patients receiving anticoagulant therapy, but most patients with a thromboembolic event will already be anticoagulated before the decision to perform the tests has been made. In addition to understanding limitations of the assays, clinicians also need to be aware of which patients should be tested and not obtain testing on patients unlikely to have APS. New tests and diagnostic strategies are in various stages of development and should help improve our ability to accurately diagnose this important clinical disorder.

Current and future management of pediatric venous thromboembolism

Venous thromboembolism (VTE) is an increasingly common complication encountered in tertiary care pediatric settings. The purpose of this review is to summarize the epidemiology, current and emerging pharmacotherapeutic options, and management of this disease. Over 70% of VTE occur in children with chronic diseases. Although they are seen in children of all ages, adolescents are at greatest risk. Pediatric VTE is associated with an increased risk of in-hospital mortality; recurrent VTE and post-thrombotic syndrome are commonly seen in survivors. In recent years, anticoagulation with low molecular weight heparin has emerged as the mainstay of therapy, but compliance is limited by its onerous subcutaneous administration route. New anticoagulants either already approved for use in adults or in the pipeline offer the possibility of improved dose stability and oral routes of administration. Current recommended anticoagulation course durations are derived from very limited case series and cohort data, or extrapolations from adult literature. However, the pathophysiologic underpinnings of pediatric VTE are dissimilar from those seen in adults and are often variable within groups of pediatric patients. Clinical studies and trials in pediatric VTE are underway which will hopefully improve the quality of evidence from which therapeutic guidelines are derived.

Antithrombotic therapy in neonates and children: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines

BACKGROUND

Neonates and children differ from adults in physiology, pharmacologic responses to drugs, epidemiology, and long-term consequences of thrombosis. This guideline addresses optimal strategies for the management of thrombosis in neonates and children.

METHODS

The methods of this guideline follow those described in the Methodology for the Development of Antithrombotic Therapy and Prevention of Thrombosis Guidelines: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines.

RESULTS

We suggest that where possible, pediatric hematologists with experience in thromboembolism manage pediatric patients with thromboembolism (Grade 2C). When this is not possible, we suggest a combination of a neonatologist/pediatrician and adult hematologist supported by consultation with an experienced pediatric hematologist (Grade 2C). We suggest that therapeutic unfractionated heparin in children is titrated to achieve a target anti-Xa range of 0.35 to 0.7 units/mL or an activated partial thromboplastin time range that correlates to this anti-Xa range or to a protamine titration range of 0.2 to 0.4 units/mL (Grade 2C). For neonates and children receiving either daily or bid therapeutic low-molecular-weight heparin, we suggest that the drug be monitored to a target range of 0.5 to 1.0 units/mL in a sample taken 4 to 6 h after subcutaneous injection or, alternatively, 0.5 to 0.8 units/mL in a sample taken 2 to 6 h after subcutaneous injection (Grade 2C).

CONCLUSIONS

The evidence supporting most recommendations for antithrombotic therapy in neonates and children remains weak. Studies addressing appropriate drug target ranges and monitoring requirements are urgently required in addition to site- and clinical situation-specific thrombosis management strategies.

Laboratory testing in pediatric rheumatology

In children, laboratory evaluations can assist in the screening of patients for inflammatory disorders, confirm diagnoses, allow for monitoring of disease activity and response to therapy, and suggest prognoses and risk of morbidities associated with rheumatic diseases. This review provides an overview of the usefulness and interpretation of both the commonly ordered tests ordered by the general pediatrician as well as those frequently used in the pediatric rheumatology clinic for diagnosis and disease monitoring. Studies discussed include the complete blood count, acute phase reactants, autoantibodies, serum complement, urinalysis, streptococcal antibody tests, and commonly used genetic studies.

Reevaluation of predictive value of ACL and anti-β2GP1 antibody for thrombosis in patients with systemic lupus erythematosus: from a perspective of a practical world

Detection of ACL (anticardiolipin, ACL) and anti-β2GP1 (beta2 glycoprotein1, β2GP1) antibody has been widely used, and the criteria of APS (Antiphospholipid syndrome, APS) have been used for the prediction of thrombosis in patients with SLE. What is the exact predictive value of these two antibodies? Is it really necessary to apply the criteria of APS to each patient just for the purpose of prediction of thrombosis? The aim of this retrospective study is to reevaluate the predictive value of different combination of ACL and anti-β2GP1 antibody for thrombosis formation in Chinese patients with SLE. Patients fulfilling the 1997 ACR classification criteria for SLE were enrolled and retrospectively analyzed. Thrombosis was confirmed by ultrasound, cerebral MRI, computed tomography pulmonary angiogram and angiography. Both IgG and IgM isotype of ACL and anti-β2GP1 antibody were detected with ELISA kit. ROC curves and other parameters of diagnostic test for different combination of ACL and anti-β2GP1 were analyzed and compared. 175 patients were recruited and thrombosis was diagnosed in 49 patients. In patients with thrombosis, 95.9% had been treated with glucocorticoids before detection of the two antibodies, 44.9% had hypertension and 53.1% had hyperlipidemia. ACL was positive in 28 patients (16%), and anti-β2GP1 antibody was positive in 21 patients (12%). The presence of a low or higher titer of either ACL (>12 RU/ml) or anti-β2GP1 antibody (>20 RU/ml) once has the highest predictive accuracy. The sensitivity, the specificity, the Youden's index and the area under ROC curve are 61.11%, 81.11%, 0.4222 and 0.711 respectively. A transient low or higher titer of ACL or anti-β2GP1 antibody had a good predictive value for thrombosis in patients with SLE, especially in those with other traditional risk factors for thrombosis and those treated with glucocorticoids.

Prevalence of annexin A5 resistance in children and adolescents with rheumatic diseases

OBJECTIVE

The underlying mechanism(s) by which antiphospholipid antibodies (aPL) result in thrombosis remains poorly understood. A significant body of evidence has evolved to support the hypothesis that antibody-mediated disruption of an annexin A5 anticoagulant shield may play a role in the pathogenesis; this proposed mechanism has not been previously studied in children.

METHODS

We investigated the association between aPL and resistance to annexin A5 anticoagulant activity in 90 children with a variety of rheumatic diseases using a novel mechanistic assay, the annexin A5 resistance assay (A5R).

RESULTS

Patients with a diagnosis of primary aPL syndrome, systemic lupus erythematosus, and mixed connective tissue disease demonstrated lower mean A5R levels (p = 0.030), higher prevalence of positive aPL (p < 0.001), and more thrombotic events (p = 0.014) compared to those with other diagnoses. Patients with persistently positive aPL had significantly lower mean A5R compared to patients with no aPL (mean A5R = 203% ± 44% vs 247% ± 35%; p < 0.001), whereas patients with transient aPL did not. Patients with thrombosis had lower A5R levels compared to those without thrombosis (mean A5R = 207% ± 36% vs 237% ± 46%; p = 0.048).

CONCLUSION

Children and adolescents with rheumatic diseases and persistent aPL have reduced annexin A5 anticoagulant activity, whereas transient, nonpathogenic aPL have less effect on annexin A5 activity.

Primary antiphospholipid syndrome presenting as renal vein thrombosis and membranous nephropathy

Antiphospholipid syndrome is a multisystem auto-immune disorder characterized by thrombotic events and the presence of circulating antiphospholipid antibodies. Large vessel involvement in the form of thrombosis/stenosis and thrombotic microangiopathy is a commonly described renal finding. However, non-thrombotic glomerulopathies are increasingly being recognized in patients with antiphospholipid syndrome. We report a rare occurrence of both renal vein thrombosis and membranous nephropathy in a previously healthy adolescent male. Investigations revealed persistently positive antiphospholipid antibodies in the absence of an underlying systemic autoimmune disorder or malignancy. Our patient responded favourably to anti-proteinuric therapy and anticoagulation with complete resolution of proteinuria and a nearly occlusive thrombus.

Aspects of anticoagulation in children

The number of children receiving anticoagulation is increasing. Thromboembolic events are associated with significant risk of morbidity and mortality although the optimal management of asymptomatic events remains unclear. Specific challenges in paediatrics include the diagnosis of thrombosis, delivery and monitoring of anticoagulation in a wide range of ages from neonates through to adolescents. The development of the haemostatic system as children age results in changing pathophysiology of thrombosis and response to anticoagulation agents. Although registry and observational studies have provided vital information, specific paediatric, prospective anticoagulation studies have been few and limited in design. The result is that much of current practice is extrapolated from adult studies. Traditional anticoagulants have significant limitations. Both heparin and warfarin are in widespread use but many fundamental questions regarding dose, therapeutic range, efficacy and optimum duration have not been fully answered. Alternative agents, such as direct thrombin inhibitors and the selective anti-factor Xa inhibitor fondaparinux, may have advantages for children. Clinical trials in adults and preliminary data in children are promising but caution should be applied until specific paediatric studies have demonstrated safety and efficacy.

Thrombosis in the pediatric population

Whereas thrombotic events in critically ill children do not occur as commonly as in adults, they are being recognized with increasing frequency in the pediatric intensive care unit. The reasons for this are not clear but likely include an increased awareness of the problem and the ability to make a diagnosis using relatively noninvasive tests. In this section, I attempt to define the extent of the problem, summarize and discuss the relevant literature (pointing out where published experience in the pediatric population differs from that in adult patients), and suggest some guidelines regarding thrombophilia treatment and the management of thrombotic events.

Autologous hematopoietic stem cell transplantation for childhood autoimmune disease

Autologous and allogeneic hematopoietic stem cell transplantation (HSCT) can be used in the management of patients with autoimmune disorders. Experience gained in adults has helped to better define the conditioning regimens required and appropriate selection of patients who are most likely to benefit from autologous HSCT. The field has been shifting toward the use of safer and less intense nonmyeloablative regimens used earlier in the disease course before patients accumulate extensive irreversible organ damage. This article reviews the experience of using autologous HSCT in treating the most common childhood autoimmune and rheumatic diseases, primarily juvenile idiopathic arthritis, systemic lupus erythematosus, and diabetes mellitus.

Thrombotic risk assessment in the antiphospholipid syndrome requires more than the quantification of lupus anticoagulants

Lupus anticoagulants (LACs) are associated with thromboembolic complications (TECs). LACs can be detected by their anticoagulant properties in thrombin generation assays, by the peak height (PH) and lag time (LT). To assess the thrombotic risk in LAC-positive patients, we have expressed the LAC activity quantitatively by PH/LT calibration curves, constructed for mixtures of monoclonal antibodies against beta2-glycoprotein I (beta2GPI) and prothrombin, spiked in normal plasma. PH/LT was determined in LAC patients, with (n = 38) and without (n = 21) TECs and converted into arbitrary LAC units. LAC titers ranged from 0 to 200 AU/mL, with 5 of 59 patients being negative. In the positive LAC titer population (54 of 59), LAC and anti-beta2GPI immunoglobulin G (IgG) titers correlated with TECs, with odds ratios of 3.54 (95% CI, 1.0-1.7) and 10.0 (95% CI, 1.98-50.6), respectively. In patients with single or combined low titers, useful predictions on thrombosis could be made only after additional measurements of soluble P-selectin and factor VII. This layered strategy yielded positive and negative predictive values, sensitivity, and specificity values approximately 90% in this subgroup. Hence, LAC and anti-beta2GPI IgG titers, when combined with selected markers of the hypercoagulable state, allow a relevant thrombotic risk assessment in nearly all patients with LACs.

Severe paediatric systemic lupus erythematosus nephritis--a single-centre experience

BACKGROUND

Paediatric patients with systemic lupus erythematosus (SLE) often have severe presentations including lupus nephritis (LN). Few paediatric studies have evaluated the anticardiolipin antibody (aCL) and renal histology. The purpose of this study was to evaluate clinicopathologic features, including aCL, short-term clinical and renal histologic outcomes of paediatric patients with new-onset SLE nephritis.

METHODS

We conducted a single centre, retrospective inception cohort study. Charts were reviewed at presentation (initial renal biopsy), 6-month (follow-up biopsy) and 12-month follow-up.

RESULTS

The population consisted of 21 patients (median age, 14.5 years): 19/21 were female, 6/21 African American, 3/21 Asian, 9/21 Caucasian and 3/21 Hispanic. At presentation, 19/21 had elevated aCL, 15/21 hypertensive, 12/21 nephrotic and 7/21 required haemodialysis (HD)-2/7 HD patients had thrombotic microangiopathy, 1/7 crescentic glomerulonephritis. Two patients had thromboembolism: both had aCL, were taking oral contraceptives and required HD, one was nephrotic and the other had elevated lupus anticoagulant. Initial biopsies revealed 6/21 ISN/RPS class II nephritis, 3/21 class III, 7/21 class IV and 5/21 class V. Treatment consisted of methylprednisolone, corticosteroids, cyclophosphamide or mycophenolate mofetil. Follow-up biopsies revealed 12/13 to have improved histology. Indication for a follow-up biopsy was severe illness at presentation. At 12-month follow-up, no patients were nephrotic (P < 0.001) or required HD (P < 0.001), and 3/14 had elevated aCL (P < 0.001).

CONCLUSION

Elevated aCL, hypertension, nephrotic syndrome and need for HD were common presentations among our paediatric SLE nephritis population. Renal histology and aCL were helpful in the therapeutic management.