Thrombosis recurrence and major bleeding in non-anticoagulated thrombotic antiphospholipid syndrome patients: Prospective study from antiphospholipid syndrome alliance for clinical trials and international networking (APS ACTION) clinical database and repository ("Registry")

BACKGROUND

Long-term anticoagulant therapy is generally recommended for thrombotic antiphospholipid syndrome (TAPS) patients, however it may be withdrawn or not introduced in routine practice.

OBJECTIVES

To prospectively evaluate the risk of thrombosis recurrence and major bleeding in non-anticoagulated TAPS patients, compared to anticoagulated TAPS, and secondly, to identify different features between those two groups.

PATIENTS/METHODS

Using an international registry, we identified non-anticoagulated TAPS patients at baseline, and matched them with anticoagulated TAPS patients based on gender, age, type of previous thrombosis, and associated autoimmune disease. Thrombosis recurrence and major bleeding were prospectively analyzed using Kaplan-Meier method and compared using a marginal Cox's regression model.

RESULTS

As of June 2022, 94 (14 %) of the 662 TAPS patients were not anticoagulated; and 93 of them were matched with 181 anticoagulated TAPS patients (median follow-up 5 years [interquartile range 3 to 8]). The 5-year thrombosis recurrence and major bleeding rates were 12 % versus 10 %, and 6 % versus 7 %, respectively (hazard ratio [HR] 1.38, 95 % confidence interval [CI] 0.53 to 3.56, p = 0.50 and HR 0.53; 95 % CI 0.15 to 1.86; p = 0.32, respectively). Non-anticoagulated patients were more likely to receive antiplatelet therapy (p < 0.001), and less likely to have more than one previous thrombosis (p < 0.001) and lupus anticoagulant positivity (p = 0.01).

CONCLUSION

Fourteen percent of the TAPS patients were not anticoagulated at recruitment. Their recurrent thrombosis risk did not differ compared to matched anticoagulated TAPS patients, supporting the pressing need for risk-stratified secondary thrombosis prevention trials in APS investigating strategies other than anticoagulation.

Damage measured by Damage Index for Antiphospholipid Syndrome (DIAPS) in antiphospholipid antibody-positive patients included in the APS ACTION registry

OBJECTIVES

Our primary objective was to quantify damage burden measured by Damage Index for Antiphospholipid Syndrome (DIAPS) in aPL-positive patients with or without a history of thrombosis in an international cohort (the APS ACTION cohort). Secondly, we aimed to identify clinical and laboratory characteristics associated with damage in aPL-positive patients.

METHODS

In this cross-sectional study, we analysed the baseline damage in aPL-positive patients with or without APS classification. We excluded patients with other autoimmune diseases. We analysed the demographic, clinical and laboratory characteristics based on two subgroups: (i) thrombotic APS patients with high vs low damage; and (ii) non-thrombotic aPL-positive patients with vs without damage.

RESULTS

Of the 826 aPL-positive patients included in the registry as of April 2020, 586 with no other systemic autoimmune diseases were included in the analysis (412 thrombotic and 174 non-thrombotic). In the thrombotic group, hyperlipidaemia (odds ratio [OR] 1.82; 95% CI 1.05, 3.15; adjusted P = 0.032), obesity (OR 2.14; 95% CI 1.23, 3.71; adjusted P = 0.007), aβ2GPI high titres (OR 2.33; 95% CI 1.36, 4.02; adjusted P = 0.002) and corticosteroid use (ever) (OR 3.73; 95% CI 1.80, 7.75; adjusted P < 0.001) were independently associated with high damage at baseline. In the non-thrombotic group, hypertension (OR 4.55; 95% CI 1.82, 11.35; adjusted P = 0.001) and hyperlipidaemia (OR 4.32; 95% CI 1.37, 13.65; adjusted P = 0.013) were independent predictors of damage at baseline; conversely, single aPL positivity was inversely correlated with damage (OR 0.24; 95% CI 0.075, 0.77; adjusted P = 0.016).

CONCLUSIONS

DIAPS indicates substantial damage in aPL-positive patients in the APS ACTION cohort. Selected traditional cardiovascular risk factors, steroids use and specific aPL profiles may help to identify patients more prone to present with a higher damage burden.

Viewpoint: Lupus anticoagulant detection and interpretation in antiphospholipid syndrome

Lupus anticoagulant (LA) is a well-established risk factor for the clinical manifestations of antiphospholipid syndrome (APS). Accurate LA detection is an essential prerequisite for optimal diagnosis and management of patients with APS or aPL carriers. Variability remains a challenge in LA testing, with reliable detection influenced by multiple factors, including pre-analytical conditions, anticoagulation treatment, choice of tests and procedures performed, as well as interpretation of results, that can lead to false-positives or negatives. A standardised approach to LA testing, following current guidance, based on published data and international consensus, and with attention to detail, is required to underpin accurate detection of LA. Future work should focus on better characterisation of the nature of LA, which may ultimately lead to improved diagnosis and management of patients with APS and aPL carriers. This article reviews current practice and challenges, providing an overview on detection of LA.

Platelets and Thrombotic Antiphospholipid Syndrome

Antiphospholipid antibody syndrome (APS) is an autoimmune disorder characterised by thrombosis and the presence of antiphospholipid antibodies (aPL): lupus anticoagulant and/or IgG/IgM anti-β2-glycoprotein I and anticardiolipin antibodies. APS carries significant morbidity for a relatively young patient population from recurrent thrombosis in any vascular bed (arterial, venous, or microvascular), often despite current standard of care, which is anticoagulation with vitamin K antagonists (VKA). Platelets have established roles in thrombosis at any site, and platelet hyperreactivity is clearly demonstrated in the pathophysiology of APS. Together with excess thrombin generation, platelet activation and aggregation are the common end result of all the pathophysiological pathways leading to thrombosis in APS. However, antiplatelet therapies play little role in APS, reserved as a possible option of low dose aspirin in addition to VKA in arterial or refractory thrombosis. This review outlines the current evidence and mechanisms for excessive platelet activation in APS, how it plays a central role in APS-related thrombosis, what evidence for antiplatelets is available in clinical outcomes studies, and potential future avenues to define how to target platelet hyperreactivity better with minimal impact on haemostasis.

Associations Among Antiphospholipid Antibody Types, Isotypes, and Titers: An AntiPhospholipid Syndrome Alliance for Clinical Trials and InternatiOnal Networking (APS ACTION) Study

Several antiphospholipid antibody (aPL) profiles ("triple" and lupus anticoagulant [LA] positivity) are associated with a higher risk for clinical manifestations of antiphospholipid syndrome (APS). Further risk is correlated with higher levels of anticardiolipin antibody (aCL) and anti-β2 glycoprotein-I antibody (aβ2GPI), and with aPL persistence. Given that the 3 aPL tests detect partially overlapping sets of antibodies, the primary goal of this study was to characterize the associations among aPL tests using AntiPhospholipid Syndrome Alliance for Clinical Trials and InternatiOnal Networking (APS ACTION) core laboratory data. The APS ACTION Registry includes annually followed adult patients with positive aPL based on the Revised Sapporo Classification Criteria. We analyzed baseline and prospective core laboratory data of the registry for associations among aPL tests using the Spearman rank correlation with Bonferroni-adjusted significance level for multiple comparisons. An aPL Load was calculated based on 6 tests (aCL IgG/IgM/IgA and aβ2GPI IgG/IgM/IgA); a receiver operating characteristic curve was used to evaluate the diagnostic performance of the aPL Load in predicting LA positivity. In 351 patients simultaneously tested for LA, aCL, and aβ2GPI, the frequency of moderate-to-high (≥40 U) titers of aCL and aβ2GPI IgG/IgM/IgA was higher in patients who were positive for LA vs those who were negative. An aPL Load was calculated for each patient to assess the overall aPL burden. For every 1-point increase in the aPL Load, the possibility of a positive LA test increased by 32% (odds ratio, 1.32; 95% CI, 1.2-1.5; P < .001). Based on core laboratory data from a large international registry, most aPL enzyme-linked immunosorbent assay ≥40 U and a high calculated aPL Load combining 6 aPL enzyme-linked immunosorbent assays were predictive of a positive LA. These data suggest that the combined quantitative burden of aPL may provide a mechanistic explanation of a positive LA.

Fluctuation of Anti-Domain 1 and Anti-Β2 Glycoprotein I Antibody Titers Over Time in Patients with Persistently Positive Antiphospholipid Antibodies

OBJECTIVE

This work aims at evaluating longitudinally titers of antibodies against β2-glycoprotein I (β2GPI) and domain 1 (anti-D1), identifying predictors of the variation of anti-D1 and anti-β2GPI antibody titers and clarifying whether antibody titer fluctuations predict thrombosis in a large international cohort of patients persistently positive for antiphospholipid antibodies (aPL), the "APS ACTION Registry".

METHODS

Patients with available blood samples from at least 4 time points were included. Anti-β2GPI and anti-D1 IgG were tested by chemiluminescence (BioFlash, INOVA Diagnostics).

RESULTS

In a cohort of 230 patients, anti-D1 and anti-β2GPI titers decreased significantly over time (p<0.0001 and p=0.010, respectively). After adjustment for age, gender, and number of positive aPL tests, the fluctuation of anti-D1 and anti-β2GPI titers was associated with treatment with hydroxychloroquine (HCQ) at each time-point. Treatment with HCQ, but not immunosuppressors, was associated with 1.3-fold and 1.4-fold decrease in anti-D1 and anti-β2GPI titers, respectively. Incident vascular events were associated with 1.9-fold and 2.1-fold increase of anti-D1 and anti-β2GPI titers, respectively. Anti-D1 and anti-β2GPI titers at the time of thrombosis were lower compared to the other time-points: 1.6-fold decrease in anti-D1 titers and 2-fold decrease in anti-β2GPI titers conferred an OR for incident thrombosis of 6.0 (95%CI 0.62-59.3) and 9.4 (95%CI 1.1-80.2), respectively.

CONCLUSIONS

Treatment with HCQ and incident vascular events significant predicted anti-D1 and anti-β2GPI titer fluctuation over time. Both anti-D1 and anti-β2GPI titers drop around the time of thrombosis, with potential clinical relevance. This article is protected by copyright. All rights reserved.

AB0522 EARLY DAMAGE AS MEASURED BY THE DAMAGE INDEX FOR ANTIPHOSPHOLIPID SYNDROME (DIAPS) IS NOT A PREDICTOR OF MORTALITY IN THROMBOTIC ANTIPHOSPHOLIPID SYNDROME

Background

Antiphospholipid syndrome (APS) patients experience damage accrual (1) but correlation with mortality is rarely reported. In systemic lupus erythematosus (SLE), early damage accrued in the first year of disease is a predictor of mortality (2).

Objectives

To determine whether damage accrued within the first year after APS onset as measured by the Damage Index for APS (DIAPS) predicts mortality.

Methods

Single-centre retrospective analysis of thrombotic APS patients (2006 Sydney criteria). The disease onset was determined as the time the first thrombotic event related to APS was diagnosed. Annual DIAPS assessments were determined for each patient. Early damage was considered to be a score ≥1 at the initial assessment (six months). DIAPS is shown as median (interquartile range [IQR]). Survival was analysed by the Kaplan-Meier method. Cox regression analysis was performed to investigate predictors of mortality.

Results

A total of 197 patients (71.1% female; 65.9% primary APS; 72.4% Caucasian) with a median age at APS onset of 40 years (IQR 51 - 28) were followed for up to 43 years (median 10 years). Cumulative damage developed in 143 (73.6%) patients with a median DIAPS of 1 (IQR 2 - 0) at the last visit. Early damage was present in 69 (35.0%) patients. Patients with early damage had similar sex distribution (p=0.733), age at disease onset (p=0.526) and median time of follow-up (p=0.181) comparing to those without early damage. Secondary APS (SAPS) (odds ratio [OR] 1.89, 95% CI 1.03 - 3.48, p=0.041) and having a first arterial event (OR 7.24, 95% CI 3.74 - 14.03, p<0.001) were associated with early damage. Twenty-three patients (11.7%) died. SAPS (p=0.009), male sex (p=0.008) and age at onset ≥40years (p=0.001) were risk factors for death (Table 1). Early damage was not associated with death (hazard ratio [HR] 1.65, 95% CI 0.73 - 3.78, p=0.231; Figure 1: survival curve) even after adjusting individually for APS category (secondary, p=0.446), sex (male, p=0.374), age at onset ≥40years (p=0.115) and type of event (arterial, p=0.555).

Table 1.

Predictors of mortality.

Crude analysisAdjusted analysis†HR (95% CI)p-valueHR (95% CI)p-valueMale sex3.14 (1.35 – 7.33)0.0081.46 (0.63 – 3.36)0.374Age at APS onset ≥ 40 years5.34 (1.9 – 14.53)0.0011.95 (0.85 – 4.50)0.115Caucasian0.95 (0.35 – 2.57)0.9181.61 (0.70 – 3.70)0.257Secondary APS3.07 (1.32 – 7.12)0.0091.38 (0.59 – 3.20)0.446First event (arterial)1.85 (0.79 – 4.27)0.1511.32 (0.53 – 3.32)0.555Early damage1.65 (0.73 – 3.78,0.231--

† In this column, we present the Early Damage hazard ratio and 95% confidence intervals for death adjusted for the variable in each row. Statistically significant values are presented in bold. APS, antiphospholipid syndrome; CI, confidence interval; DIAPS, Damage Index for Antiphospholipid Syndrome; HR, hazard ratio.

Figure 1.

Survival probability in patients with and without early damage.

Conclusion

Unlike SLE, early damage accrual accessed by DIAPS is not a predictor of mortality regardless of the nature of the thrombotic event, gender, APS category and age at APS onset.

References

[1]GRIKA EP, ZIAKAS PD, ZINTZARAS E, MOUTSOPOULOS HM, VLACHOYIANNOPOULOS PG: Morbidity, Mortality, and Organ Damage in Patients with Antiphospholipid Syndrome. J Rheumatol. 2012;39(3):516–23.

[2]RAHMAN P, GLADMAN DD, UROWITZ MB, HALLETT D, TAM LS: Early damage as measured by the SLICC/ACR damage index is a predictor of mortality in systemic lupus erythematosus. Lupus. 2001;10(2):93–6.

Disclosure of Interests

Pedro Gaspar: None declared, Filipa Farinha: None declared, Zara Sayar: None declared, Maria Efthymiou: None declared, Hannah Cohen Speakers bureau: Honoraria for lectures from Bayer Healthcare (outside the submitted work)., Consultant of: Consultancy fees from UCB Biopharma paid to University College London Hospitals Charity (outside the submitted work)., David Isenberg: None declared

POS0462 HYDROXYCHLOROQUINE REDUCES THE TITERS OF ANTI-DOMAIN 1 ANTIBODIES OVER TIME IN PATIENTS WITH PERSISTENTLY POSITIVE ANTIPHOSPHOLIPID ANTIBODIES: RESULTS FROM THE APS ACTION CLINICAL DATABASE AND REPOSITORY (“REGISTRY”)

Background

Data on fluctuation of antibodies directed against domain 1 (anti-D1) of β2-glycoprotein I (β2GPI) are scarce. Patients with antiphospholipid syndrome (APS) and all three criteria tests for antiphospholipid antibodies (aPL) display higher titers of anti-D1, which correlate with anti-β2GPI levels.

Objectives

This project aims at evaluating predictors of the variation of anti-D1 titers over time in a large international cohort of persistently aPL positive patients.

Methods

AntiPhospholipid Syndrome Alliance For Clinical Trials and InternatiOnal Networking (APS ACTION) Registry was created to study the course of persistently aPL-positive patients with or without autoimmune disorders over at least 10 years. Inclusion criteria are positive aPL by Updated Sapporo Criteria tested within one year prior to enrolment. Patients are followed every 12±3 months with clinical data and blood collection. Patients with available blood samples from at least three time points were included in this analysis. Anti-β2GPI and anti-D1 IgG were tested by chemiluminescence (BioFlash, Werfen) at APS ACTION core laboratories. Positive results were defined as >20 CU, according to the manufacturer. Clinical data were retrieved from APS ACTION online database. Anti-D1 titers within the same subject were compared by Friedman’s test. A mixed linear model was built to identify predictors of the fluctuation of anti-D1 antibody titers over time.

Results

In this longitudinal study, 230 patients with anti-D1 tested at 4 time points were included (Table 1). Patients with thrombotic APS had anti-D1 titers significantly higher than those without thrombosis (p=0.022). Among 135 patients with at least one anti-D1 positive result, anti-D1 titers varied significantly over time (Friedman statistics: 508.5, p<0.0001; anti-D1 geometric mean at baseline 189.0; T1 132.3 [-15%]; T2 113.8 [-17%]; T3 109.2 [-6% versus T2, -38% versus T1]). Anti-D1 titers were significantly higher at baseline compared to T3 (p=0.029). In the 4 years of follow-up, 18 new thrombotic events occurred. Patients with double/triple aPL positivity displayed 12.5 fold increase [95%CI 7.4-20.0] in baseline anti-D1 titers. After adjustment for age, gender and number of positive aPL tests, the fluctuation of anti-D1 titers was associated with treatment with hydroxychloroquine (HCQ) at each time-point. In particular, treatment with HCQ, but not those with conventional immunosuppressors, was associated with a 1.3-fold decrease in anti-D1 titers [95%CI 1.1-1.5]. In the same multivariable model, incident vascular events were associated with a 1.5 fold increase of anti-D1 titers. A concomitant diagnosis of systemic lupus erythematosus did not affect the fluctuation of anti-D1 titers.

Table 1.

Demographic and Clinical Characteristics of 230 APS ACTION Registry Patients with anti-D1 tested ≥3 time points during the follow-up

Anti-D1 pos samplesAnti-D1 neg samplesp-valueOverall sample(n=135)(n=95)(n=230)Age [years] mean (SD)42.3 (11.8)48.8 (13.0)0.000145.0 (12.7)%Female (n)71.9 (97)65.3 (62)0.35869.1 (159)Associated systemic autoimmune disease39.3 (53)44.2 (42)0.53941.3 (95)aPL without APS19.3 (26)34.7 (33)0.01025.7 (59)Thrombotic APS54.1 (73)53.7 (51)53.9 (124)Obstetric APS11.9 (16)5.3 (5)9.1 (21)Thrombotic/+obstetric APS14.8 (20)6.3 (6)11.3 (26)aCL IgG89.5 (119/133)25.5 (24/94)<0.000163.0 (143/227)aCL, IgM36.1 (48/133)27.7 (26/94)0.23432.6 (74/227)Anti-2GPI, IgG93.2 (124/133)39.4 (37/94)<0.000170.9 (161/227)Anti-2GPI, IgM34.6 (46/133)21.3 (20/94)0.04329.1 (66/227)LA82.8 (82/99)59.5 (44/74)0.00172.8 (126/173)

Conclusion

Treatment with HCQ and vascular events during follow-up were identified as significant predictors of the fluctuation of anti-D1 antibody titers over time.

Disclosure of Interests

None declared.

A one-point increase in the Damage Index for Antiphospholipid Syndrome (DIAPS) predicts mortality in thrombotic antiphospholipid syndrome

OBJECTIVES

To determine whether early damage and its kinetics measured by the Damage Index for Antiphospholipid Syndrome (DIAPS) predicts mortality.

METHODS

We carried out a single-centre retrospective analysis of thrombotic APS patients (2006 Sydney criteria), using the DIAPS for damage assessment. Early damage was considered to be at six months after disease onset; early damage increase (delta-DIAPS) was deemed to be at least a one-point rise in DIAPS within the first five years of illness. Groups were compared using appropriate statistical tests. Survival was analysed by the Kaplan-Meier method. Cox regression analysis was performed to investigate predictors of mortality.

RESULTS

A total of 197 patients (71.1% female; 65.9% primary APS; 72.4% Caucasian) were followed for up to 43 years (median 10). Damage developed in 143 (73.6%) patients. Twenty-three patients (12%) died. Secondary APS (HR 3.07, 95%CI 1.32-7.12, p=0.009), male sex (HR 3.14, 95%CI 1.35-7.33, p=0.008) and age at APS onset ≥40 years (HR 5.34, 95%CI 1.96-14.53, p=0.001) were risk factors for death. Early damage (n=69, 35.0%) was not associated with death (p=0.231). Having a first arterial event was associated with early damage (p<0.001), but not with delta-DIAPS (p=0.539) nor with the risk of death (p=0.151). Delta-DIAPS (n=53/181, 29.3%) predicted mortality (HR 5.40, 95%CI 2.33-12.52, p<0.001), even after adjusting individually for APS category (secondary), sex (male), early damage and age at APS onset (≥40 years) (all p<0.005).

CONCLUSIONS

Evolving damage in the first five years of illness, but not early damage, predicted mortality regardless of the nature of the first thrombotic event, sex, APS category and age.

Characteristics of Patients With Antiphospholipid Antibody Positivity in the APS ACTION International Clinical Database and Repository

OBJECTIVE

To describe the baseline characteristics of patients with positivity for antiphospholipid antibodies (aPLs) who were enrolled in an international registry, the Antiphospholipid Syndrome (APS) Alliance for Clinical Trials and International Networking (APS ACTION) clinical database and repository, overall and by clinical and laboratory subtypes.

METHODS

The APS ACTION registry includes adults who persistently had positivity for aPLs. We evaluated baseline sociodemographic and aPL-related (APS classification criteria and "non-criteria") characteristics of patients overall and in subgroups (aPL-positive without APS, APS overall, thrombotic APS only, obstetric APS only, and both thrombotic APS/obstetric APS). We assessed baseline characteristics of patients tested for the presence of three aPLs (lupus anticoagulant [LAC] test, anticardiolipin antibody [aCL], and anti-β2 -glycoprotein I [anti-β2 GPI]) antibodies by aPL profiles (LAC only, single, double, and triple aPL positivity).

RESULTS

The 804 aPL-positive patients assessed in the present study had a mean age of 45 ± 13 years, were 74% female, and 68% White; additionally, 36% had other systemic autoimmune diseases. Of these 804 aPL-positive patients, 80% were classified as having APS (with 55% having thrombotic APS, 9% obstetric APS, and 15% thrombotic APS/obstetric APS). In the overall cohort, 71% had vascular thrombosis, 50% with a history of pregnancy had obstetric morbidity, and 56% had experienced at least one non-criteria manifestation. Among those with three aPLs tested (n = 660), 42% were triple aPL-positive. While single-, double-, and triple aPL-positive subgroups had similar frequencies of vascular, obstetric, and non-criteria events, these events were lowest in the single aPL subgroup, which consisted of aCLs or anti-β2 GPI only.

CONCLUSION

Our study demonstrates the heterogeneity of aPL-related clinical manifestations and laboratory profiles in a multicenter international cohort. Within single aPL positivity, LAC may be a major contributor to clinical events. Future prospective analyses, using standardized core laboratory aPL tests, will help clarify aPL risk profiles and improve risk stratification.

COVID-19 and antiphospholipid antibodies: A position statement and management guidance from AntiPhospholipid Syndrome Alliance for Clinical Trials and InternatiOnal Networking (APS ACTION)

Coronavirus disease 2019 (COVID-19) is associated with a high rate of thrombosis. Prolonged activated partial thromboplastin times (aPTT) and antiphospholipid antibodies (aPL) are reported in COVID-19 patients. The majority of publications have not reported whether patients develop clinically relevant persistent aPL, and the clinical significance of new aPL-positivity in COVID-19 is currently unknown. However, the reports of aPL-positivity in COVID-19 raised the question whether common mechanisms exist in the pathogenesis of COVID-19 and antiphospholipid syndrome (APS). In both conditions, thrombotic microangiopathy resulting in microvascular injury and thrombosis is hypothesized to occur through multiple pathways, including endothelial damage, complement activation, and release of neutrophil extracellular traps (NETosis). APS-ACTION, an international APS research network, created a COVID-19 working group that reviewed common mechanisms, positive aPL tests in COVID-19 patients, and implications of COVID-19 infection for patients with known aPL positivity or APS, with the goals of proposing guidance for clinical management and monitoring of aPL-positive COVID-19 patients. This guidance also serves as a call and focus for clinical and basic scientific research.

Antiphospholipid antibodies and neurological manifestations in acute COVID-19: A single-centre cross-sectional study

BACKGROUND

A high prevalence of antiphospholipid antibodies has been reported in case series of patients with neurological manifestations and COVID-19; however, the pathogenicity of antiphospholipid antibodies in COVID-19 neurology remains unclear.

METHODS

This single-centre cross-sectional study included 106 adult patients: 30 hospitalised COVID-neurological cases, 47 non-neurological COVID-hospitalised controls, and 29 COVID-non-hospitalised controls, recruited between March and July 2020. We evaluated nine antiphospholipid antibodies: anticardiolipin antibodies [aCL] IgA, IgM, IgG; anti-beta-2 glycoprotein-1 [aβ2GPI] IgA, IgM, IgG; anti-phosphatidylserine/prothrombin [aPS/PT] IgM, IgG; and anti-domain I β2GPI (aD1β2GPI) IgG.

FINDINGS

There was a high prevalence of antiphospholipid antibodies in the COVID-neurological (73.3%) and non-neurological COVID-hospitalised controls (76.6%) in contrast to the COVID-non-hospitalised controls (48.2%). aPS/PT IgG titres were significantly higher in the COVID-neurological group compared to both control groups (p < 0.001). Moderate-high titre of aPS/PT IgG was found in 2 out of 3 (67%) patients with acute disseminated encephalomyelitis [ADEM]. aPS/PT IgG titres negatively correlated with oxygen requirement (FiO2 R=-0.15 p = 0.040) and was associated with venous thromboembolism (p = 0.043). In contrast, aCL IgA (p < 0.001) and IgG (p < 0.001) was associated with non-neurological COVID-hospitalised controls compared to the other groups and correlated positively with d-dimer and creatinine but negatively with FiO2.

INTERPRETATION

Our findings show that aPS/PT IgG is associated with COVID-19-associated ADEM. In contrast, aCL IgA and IgG are seen much more frequently in non-neurological hospitalised patients with COVID-19. Characterisation of antiphospholipid antibody persistence and potential longitudinal clinical impact are required to guide appropriate management.

FUNDING

This work is supported by UCL Queen Square Biomedical Research Centre (BRC) and Moorfields BRC grants (#560441 and #557595). LB is supported by a Wellcome Trust Fellowship (222102/Z/20/Z). RWP is supported by an Alzheimer's Association Clinician Scientist Fellowship (AACSF-20-685780) and the UK Dementia Research Institute. KB is supported by the Swedish Research Council (#2017-00915) and the Swedish state under the agreement between the Swedish government and the County Councils, the ALF-agreement (#ALFGBG-715986). HZ is a Wallenberg Scholar supported by grants from the Swedish Research Council (#2018-02532), the European Research Council (#681712), Swedish State Support for Clinical Research (#ALFGBG-720931), the Alzheimer Drug Discovery Foundation (ADDF), USA (#201809-2016862), and theUK Dementia Research Institute at UCL. BDM is supported by grants from the MRC/UKRI (MR/V007181/1), MRC (MR/T028750/1) and Wellcome (ISSF201902/3). MSZ, MH and RS are supported by the UCL/UCLH NIHR Biomedical Research Centre and MSZ is supported by Queen Square National Brain Appeal.

Coexistent antiphospholipid syndrome and myeloproliferative neoplasm

Antiphospholipid syndrome (APS) and myeloproliferative neoplasms (MPN) are associated with an increased risk of thrombosis. The optimal management of patients with coexistent APS and MPN has not been defined. A single centre and systematic literature review of patients with coexistent APS and MPN was performed. Cases were divided into two groups based on whether they met international consensus criteria for APS. Of the 12 studies identified, eight were excluded (leaving five of a total 54 patients), as although antiphospholipid antibodies (aPL) were documented, the diagnosis of APS was not conclusively demonstrated. Another ten patients with definite APS were identified at our centre. Fifteen patients (ten females, five males) were therefore included in this analysis (eleven definite APS and four highly likely), median age 44 (range: 13-71) years. Nine had polycythaemia vera and six, essential thrombocythaemia. Thirteen of the 15 patients (86.7%) had thrombotic APS (seven with initial venous events and six arterial) and two (13.3%) had obstetric APS. Nine patients were single-positive, and six double-positive for aPL. None were triple aPL-positive. Four patients at our centre had recurrent thrombotic/obstetric events, including while on anticoagulation/antiplatelet treatment.

Anti-protein C antibodies and acquired protein C resistance in SLE: novel markers for thromboembolic events and disease activity?

OBJECTIVES

Risk factors for thromboembolism in SLE are poorly understood. We hypothesized a possible role for protein C, based on its dual activity in inflammation and haemostasis and on the evidence of an association between acquired activated protein C (APC) resistance (APCR) and high-avidity anti-protein C antibodies (anti-PC) with a severe thrombotic phenotype in venous thrombosis APS patients.

METHODS

In a cross-sectional study of 156 SLE patients, the presence and avidity of IgG anti-PC was established by in house-ELISA, and APCR to exogenous recombinant human APC (rhAPC) and Protac (which activates endogenous protein C) was assessed by thrombin generation-based assays. Associations with aPL profile, thrombotic history and disease activity (BILAG and SLEDAI-2K) were also established.

RESULTS

Anti-PC were detected in 54.5% of patients and APCR in 59%. Anti-PC positivity was associated with APCR to both rhAPC (P <0.0001) and Protac (P =0.0001). High-avidity anti-PC, detected in 26.3% of SLE patients, were associated with APCR in patients with thrombosis only (P <0.05), and with the development of thrombosis over time (range: 0-52 years; P =0.014). High-avidity anti-PC levels correlated with SLEDAI-2K (P =0.033) and total BILAG (P =0.019); SLEDAI-2K correlated inversely with APCR to Protac (P =0.004).

CONCLUSION

Anti-PC occur in patients with SLE, independently of aPL profile, and are associated with APCR. High-avidity anti-PC are associated with thrombosis and with active disease and might prove a novel marker to monitor the risk of thrombosis and disease progression in SLE.

Antiphospholipid Antibody Profile Stability Over Time: Prospective Results From the APS ACTION Clinical Database and Repository

OBJECTIVE

The APS ACTION Registry studies long-term outcomes in persistently antiphospholipid antibody (aPL)-positive patients. Our primary objective was to determine whether clinically meaningful aPL profiles at baseline remain stable over time. Our secondary objectives were to determine (1) whether baseline characteristics differ between patients with stable and unstable aPL profiles, and (2) predictors of unstable aPL profiles over time.

METHODS

A clinically meaningful aPL profile was defined as positive lupus anticoagulant (LAC) test and/or anticardiolipin (aCL)/anti-β2 glycoprotein-I (anti-β2-GPI) IgG/M ≥ 40 U. Stable aPL profile was defined as a clinically meaningful aPL profile in at least two-thirds of follow-up measurements. Generalized linear mixed models with logit link were used for primary objective analysis.

RESULTS

Of 472 patients with clinically meaningful aPL profile at baseline (median follow-up 5.1 yrs), 366/472 (78%) patients had stable aPL profiles over time, 54 (11%) unstable, and 52 (11%) inconclusive. Time did not significantly affect odds of maintaining a clinically meaningful aPL profile at follow-up in univariate (P = 0.906) and multivariable analysis (P = 0.790). Baseline triple aPL positivity decreased (OR 0.25, 95% CI 0.10-0.64, P = 0.004) and isolated LAC test positivity increased (OR 3.3, 95% CI 1.53-7.13, P = 0.002) the odds of an unstable aPL profile over time.

CONCLUSION

Approximately 80% of our international cohort patients with clinically meaningful aPL profiles at baseline remain stable at a median follow-up of 5 years; triple aPL-positivity increase the odds of a stable aPL profile. These results will guide future validation studies of stored blood samples through APS ACTION Core Laboratories.

Monitoring of anticoagulation in thrombotic antiphospholipid syndrome

Anticoagulation is central to the management of thrombotic antiphospholipid syndrome (APS). The standard anticoagulant treatment for thrombotic APS is life-long warfarin or an alternative vitamin K antagonist. The role of direct oral anticoagulants for thrombotic APS is not established due to the lack of definitive evidence and has recently been addressed in international guidance. Other anticoagulant options include low molecular weight heparin, unfractionated heparin, and fondaparinux. In APS patients, lupus anticoagulant can affect phospholipid-dependent coagulation monitoring tests, so that they may not reflect true anticoagulation intensity. Accurate assessment of anticoagulation intensity is essential, to optimize anticoagulant dosing and facilitate thrombus resolution; minimize the risk of recurrent thrombosis or bleeding; inform assessment of whether recurrent thrombosis is related to breakthrough thrombosis while on therapeutic anticoagulation, subtherapeutic anticoagulation, non-adherence, or spurious results; and guide the management of bleeding. Knowledge of anticoagulant intensity also informs assessment and comparison of anticoagulation regimens in clinical studies. Considerations regarding anticoagulation dosing and/or monitoring of thrombotic APS patients underpin appropriate management in special situations, notably APS-related severe renal impairment, which can occur in APS or APS/systemic lupus erythematosus-related nephropathy or catastrophic APS; and APS-related thrombocytopenia. Anticoagulant dosing and monitoring in thrombotic APS patients also require consideration in anticoagulant-refractory APS and during pregnancy. In this review, we summarize the tests generally used in monitoring anticoagulant therapy, use of the main anticoagulants considered for thrombotic APS, lupus anticoagulant effects on anticoagulation monitoring tests, and strategies for appropriate anticoagulant monitoring in thrombotic APS.

Management of anticoagulant-refractory thrombotic antiphospholipid syndrome

Lifelong anticoagulation with warfarin or alternative vitamin K antagonist is the standard anticoagulant treatment for thrombotic antiphospholipid syndrome. Anticoagulant-refractory thrombotic antiphospholipid syndrome can be broadly defined as breakthrough thrombosis while on standard oral anticoagulation treatment and its management is a major challenge given the serious nature of the thrombotic disease observed, which has become refractory to oral anticoagulation. The factors (genetic and cellular) that cause anticoagulant-refractory thrombotic antiphospholipid syndrome are now better understood. However, efforts to use this greater understanding have not yet transformed the capacity to treat it successfully in many patients. In this Viewpoint, we review the factors that are likely to be contributing to the cause of this syndrome and consider how they might be modified or inhibited. We also discuss management, including general strategies to minimise thrombotic risk, intensification of anticoagulation, addition of an antiplatelet agent, adjunctive treatment for thrombosis, immunomodulatory therapy, complement inhibition, vascular options, and future potential therapeutic targets.

Cluster analysis for the identification of clinical phenotypes among antiphospholipid antibody-positive patients from the APS ACTION Registry

OBJECTIVE

This study aimed to use cluster analysis (CA) to identify different clinical phenotypes among antiphospholipid antibodies (aPL)-positive patients.

METHODS

The Alliance for Clinical Trials and International Networking (APS ACTION) Registry includes persistently positive aPL of any isotype based on the Sydney antiphospholipid syndrome (APS) classification criteria. We performed CA on the baseline characteristics collected retrospectively at the time of the registry entry of the first 500 patients included in the registry. A total of 30 clinical data points were included in the primary CA to cover the broad spectrum of aPL-positive patients.

RESULTS

A total of 497 patients from international centres were analysed, resulting in three main exclusive clusters: (a) female patients with no other autoimmune diseases but with venous thromboembolism (VTE) and triple-aPL positivity; (b) female patients with systemic lupus erythematosus, VTE, aPL nephropathy, thrombocytopaenia, haemolytic anaemia and a positive lupus anticoagulant test; and (c) older men with arterial thrombosis, heart valve disease, livedo, skin ulcers, neurological manifestations and cardiovascular disease (CVD) risk factors.

CONCLUSIONS

Based on our hierarchical cluster analysis, we identified different clinical phenotypes of aPL-positive patients discriminated by aPL profile, lupus or CVD risk factors. Our results, while supporting the heterogeneity of aPL-positive patients, also provide a foundation to understand disease mechanisms, create new approaches for APS classification and ultimately develop new management approaches.

The adjusted global antiphospholipid syndrome score (aGAPSS) and the risk of recurrent thrombosis: Results from the APS ACTION cohort

OBJECTIVES

To assess whether patients with antiphospholipid syndrome (APS) and history of recurrent thrombosis have higher levels of adjusted Global AntiphosPholipid Syndrome Score (aGAPSS) when compared to patients without recurrent thrombosis.

METHODS

In this cross-sectional study of antiphospholipid antibody (aPL)-positive patients, we identified APS patients with a history of documented thrombosis from the AntiPhospholipid Syndrome Alliance For Clinical Trials and InternatiOnal Networking (APS ACTION) Clinical Database and Repository ("Registry"). Data on aPL-related medical history and cardiovascular risk factors were retrospectively collected. The aGAPSS was calculated at Registry entry by adding the points corresponding to the risk factors: three for hyperlipidemia, one for arterial hypertension, five for positive anticardiolipin antibodies, four for positive anti-β2 glycoprotein-I antibodies and four for positive lupus anticoagulant test.

RESULTS

The analysis included 379 APS patients who presented with arterial and/or venous thrombosis. Overall, significantly higher aGAPSS were seen in patients with recurrent thrombosis (arterial or venous) compared to those without recurrence (7.8 ± 3.3 vs. 6 ± 3.9, p<0.05). When analyzed based on the site of the recurrence, patients with recurrent arterial, but not venous, thrombosis had higher aGAPSS (8.1 ± SD 2.9 vs. 6 ± 3.9; p<0.05).

CONCLUSIONS

Based on analysis of our international large-scale Registry of aPL-positive patients, the aGAPSS might help risk stratifying patients based on the likelihood of developing recurrent thrombosis in APS.

Comparison of real world and core laboratory lupus anticoagulant results from the Antiphospholipid Syndrome Alliance for Clinical Trials and International Networking (APS ACTION) clinical database and repository

BACKGROUND

Variability remains a challenge in lupus anticoagulant (LA) testing.

OBJECTIVE

To validate LA test performance between Antiphospholipid Syndrome Alliance for Clinical Trials and International Networking (APS ACTION) Core laboratories and examine agreement in LA status between Core and local/hospital laboratories contributing patients to this prospective registry.

METHODS

Five Core laboratories used the same reagents, analyzer type, protocols, and characterized samples for LA validation. Non-anticoagulated registry samples were retested at the corresponding regional Core laboratories and anticoagulated samples at a single Core laboratory. Categorical agreement and discrepancies in LA status between Core and local/hospital laboratories were analyzed.

RESULTS

Clotting times for the reference/characterized plasmas used for normalized ratios were similar between Core laboratories (CV <4%); precision and agreement for LA positive/negative plasma were similar (all CV ≤5%) in the four laboratories that completed both parts of the validation exercise; 418 registry samples underwent LA testing. Agreement for LA positive/negative status between Core and local/hospital laboratories was observed in 87% (115/132) non-anticoagulated and 77% (183/237) anticoagulated samples. However, 28.7% (120/418) of samples showed discordance between the Core and local/hospital laboratories or equivocal LA results. Some of the results of the local/hospital laboratories might have been unreliable in 24.7% (41/166) and 23% (58/252) of the total non-anticoagulated and anticoagulated samples, respectively. Equivocal results by the Core laboratory might have also contributed to discordance.

CONCLUSIONS

Laboratories can achieve good agreement in LA performance by use of the same reagents, analyzer type, and protocols. The standardized Core laboratory results underpin accurate interpretation of APS ACTION clinical data.

The Impact of Systemic Lupus Erythematosus on the Clinical Phenotype of Antiphospholipid Antibody-Positive Patients: Results From the AntiPhospholipid Syndrome Alliance for Clinical Trials and InternatiOnal Clinical Database and Repository

OBJECTIVE

Although systemic lupus erythematosus (SLE) is the most common autoimmune disease associated with antiphospholipid antibodies (aPL), limited data exist regarding the impact of SLE on the clinical phenotype of aPL-positive patients. The primary objective of this study was to compare the clinical, laboratory, and treatment characteristics of aPL-positive patients with SLE with those of aPL-positive patients without SLE.

METHODS

A secure web-based data capture system was used to store patient demographic characteristics and aPL-related clinical and laboratory characteristics. Inclusion criteria included positive aPL according to the updated Sapporo classification criteria. Antiphospholipid antibody-positive patients fulfilling the American College of Rheumatology criteria for the classification of SLE ("aPL with SLE") and those with no other autoimmune diseases ("aPL only") were included in the analysis.

RESULTS

Six hundred seventy-two aPL-positive patients were recruited from 24 international centers; 426 of these patients did not have other autoimmune disease, and 197 had SLE. The frequency of thrombocytopenia, hemolytic anemia, low complement levels, and IgA anti-β₂ -glycoprotein I (anti-β₂ GPI) antibodies was higher in the aPL-positive patients with SLE, whereas the frequency of cognitive dysfunction and IgG anti-β₂ GPI antibodies was higher in the aPL-only group. The frequency of arterial and venous thromboses (including recurrent) as well as pregnancy morbidity was similar in the 2 groups. The prevalence of cardiovascular disease risk factors at the time of entry into the registry entry did not differ between the 2 groups, with the exception of current smoking, which was more frequent in aPL-positive patients with SLE.

CONCLUSION

Although the frequencies of thrombosis and pregnancy morbidity are similar in aPL-positive patients with and those without SLE, the diagnosis of SLE in patients with persistently positive aPL is associated with an increased frequency of thrombocytopenia, hemolytic anemia, low complement levels, and positive IgA anti-β₂ GPI antibodies.

The comparison of real world and core laboratory antiphospholipid antibody ELISA results from antiphospholipid syndrome alliance for clinical trials & international networking (APS ACTION) clinical database and repository analysis

BACKGROUND

The APS ACTION International Clinical Database and Repository includes a secure web-based data capture system storing patient information including demographics, antiphospholipid antibodies (aPL)-related medical history, and aPL tests. Despite efforts at harmonization, inter-assay variability remains a problem in aPL testing. As a clinical repository open to researchers, ensuring comparability between assays and consistency in results between APS ACTION laboratories is essential to the validity of studies emerging from this network.

OBJECTIVE

To assess the level of agreement between an aPL-registry inclusion and core laboratory (core lab) anticardiolipin antibody (aCL) and anti-β₂-glycoprotein-I antibody (aβ₂GPI) ELISA testing results.

METHODS

Patients are recruited from 25 international centers based on positive aPL tests at inclusion. All samples are retested at the corresponding national APS ACTION core lab to confirm aPL positivity based on standard validated protocols. We analysed the categorical agreement, degree of linear association, and correlation between inclusion (local laboratory) and core lab aPL tests. Samples were included in this study only if results of aPL testing with ELISA at baseline were available.

RESULTS

497 registry samples underwent confirmatory aPL tests. Categorical agreement between the inclusion and core lab values, as expressed by Cohen's kappa coefficients, ranged between 0.61 and 0.80 (as substantial agreement). The correlation between quantitative results in the aCL and aβ₂GPI was better for IgM and IgA compared to IgG (Spearman rho 0.789 and 0.666 vs. 0.600 for aCL and rho 0.892 and 0.744 vs. 0.432 for aβ₂GPI).

CONCLUSIONS

The results of inclusion for aCL and aβ₂GPI tests used for recruitment into the registry were in agreement to the results obtained by the APS ACTION core laboratories; aCL and aβ₂GPI results showed very good categorical agreement. This agreement increased when considering high titer (>40 units) samples. APS ACTION is a reliable and useful research resource for APS.

Use of direct oral anticoagulants in antiphospholipid syndrome

The direct oral anticoagulants (DOACs) are therapeutic alternatives to warfarin and other vitamin K antagonists (VKAs), and constitute the standard of care for many indications. VKAs constitute the conventional therapy for the treatment and secondary thromboprophylaxis of thrombotic antiphospholipid syndrome (APS), but are often problematic, owing to the variable sensitivity of thromboplastins to lupus anticoagulant. Thus, the International Normalized Ratio may not accurately reflect anticoagulation intensity, or be clinically effective. Definition of the current role of DOACs in the treatment of APS is based on limited clinical trial data and information from other sources, including manufacturers' data, case series or cohort studies, and expert consensus. The Rivaroxaban in Antiphospholipid Syndrome (RAPS) randomized controlled trial (RCT), which had a laboratory surrogate primary outcome measure, suggests that rivaroxaban has the potential to be an effective and convenient alternative to warfarin in thrombotic APS patients with a single venous thromboembolism event requiring standard-intensity anticoagulation. However, further studies, in particular to provide better long-term efficacy and safety data, are needed before it can be widely recommended. APS patients are clinically heterogeneous, with the risk of recurrent thrombosis and the intensity of anticoagulation being influenced by their clinical phenotype and risk profile. DOAC trials involving homogeneous thrombotic APS populations, with the antiphospholipid antibody status well defined, will help to optimize the appropriate treatment in APS patient subgroups. Ongoing and emerging DOAC RCTs should provide further information to guide the use of DOACs in APS patients. Optimal identification of APS patients is a key step in working towards improved therapeutic strategies in these individuals.

Rivaroxaban versus warfarin to treat patients with thrombotic antiphospholipid syndrome, with or without systemic lupus erythematosus (RAPS): a randomised, controlled, open-label, phase 2/3, non-inferiority trial

Background

Rivaroxaban is established for the treatment and secondary prevention of venous thromboembolism, but whether it is useful in patients with antiphospholipid syndrome is uncertain.

Methods

This randomised, controlled, open-label, phase 2/3, non-inferiority trial, done in two UK hospitals, included patients with antiphospholipid syndrome who were taking warfarin for previous venous thromboembolism, with a target international normalised ratio of 2·5. Patients were randomly assigned 1:1 to continue with warfarin or receive 20 mg oral rivaroxaban daily. Randomisation was done centrally, stratified by centre and patient type (with vs without systemic lupus erythematosus). The primary outcome was percentage change in endogenous thrombin potential (ETP) from randomisation to day 42, with non-inferiority set at less than 20% difference from warfarin in mean percentage change. Analysis was by modified intention to treat. Other thrombin generation parameters, thrombosis, and bleeding were also assessed. Treatment effect was measured as the ratio of rivaroxaban to warfarin for thrombin generation. This trial is registered with the ISRCTN registry, number ISRCTN68222801.

Findings

Of 116 patients randomised between June 5, 2013, and Nov 11, 2014, 54 who received rivaroxaban and 56 who received warfarin were assessed. At day 42, ETP was higher in the rivaroxaban than in the warfarin group (geometric mean 1086 nmol/L per min, 95% CI 957–1233 vs 548, 484–621, treatment effect 2·0, 95% CI 1·7–2·4, p<0·0001). Peak thrombin generation was lower in the rivaroxaban group (56 nmol/L, 95% CI 47–66 vs 86 nmol/L, 72–102, treatment effect 0·6, 95% CI 0·5–0·8, p=0·0006). No thrombosis or major bleeding were seen. Serious adverse events occurred in four patients in each group.

Interpretation

ETP for rivaroxaban did not reach the non-inferiority threshold, but as there was no increase in thrombotic risk compared with standard-intensity warfarin, this drug could be an effective and safe alternative in patients with antiphospholipid syndrome and previous venous thromboembolism.

Funding

Arthritis Research UK, Comprehensive Clinical Trials Unit at UCL, LUPUS UK, Bayer, National Institute for Health Research Biomedical Research Centre.

Direct Oral Anticoagulants for Thromboprophylaxis in Patients with Antiphospholipid Syndrome

The current mainstay of the treatment and secondary thromboprophylaxis of thrombotic antiphospholipid syndrome (APS) is anticoagulation with warfarin or other vitamin K antagonists (VKAs). In addition to their well-known limitations, VKAs are often problematic in APS patients because of the variable sensitivity of thromboplastins to lupus anticoagulant. As a result, the international normalized ratio may not accurately reflect the intensity of anticoagulation. Direct oral anticoagulants (DOACs) are established as therapeutic alternatives to VKAs for a wide range of indications, including the treatment and secondary prevention of venous thromboembolism. Definition of the role of DOACs in the treatment of thrombotic APS is emerging with the results of recent and ongoing clinical studies. This review focuses on the current situation with regard to DOACs for secondary thromboprophylaxis in APS and issues pertinent to DOAC use in APS patients, as well as potential future directions.

Rivaroxaban limits complement activation compared with warfarin in antiphospholipid syndrome patients with venous thromboembolism

Essentials Complement activation has a pathogenic role in thrombotic antiphospholipid syndrome (APS). Coagulation proteases such as factor Xa can activate complement proteins. Complement activation markers were elevated in anticoagulated thrombotic APS patients. Complement activation decreased in APS patients switching from warfarin to rivaroxaban.

SUMMARY

Background Complement activation may play a major role in the pathogenesis of thrombotic antiphospholipid syndrome (APS). Coagulation proteases such as factor Xa can activate complement proteins. Aims To establish whether rivaroxaban, a direct factor Xa inhibitor, limits complement activation compared with warfarin in APS patients with previous venous thromboembolism (VTE). Methods A total of 111 APS patients with previous VTE, on warfarin target INR 2.5, had blood samples taken at baseline and at day 42 after randomization in the RAPS (Rivaroxaban in Antiphospholipid Syndrome) trial. Fifty-six patients remained on warfarin and 55 switched to rivaroxaban. Fifty-five normal controls (NC) were also studied. Markers of complement activation (C3a, C5a, terminal complement complex [SC5b-9] and Bb fragment) were assessed. Results APS patients had significantly higher complement activation markers compared with NC at both time-points irrespective of the anticoagulant. There were no differences between the two patient groups at baseline, or patients remaining on warfarin at day 42. In 55 patients randomized to rivaroxaban, C3a, C5a and SC5b-9 were lower at day 42 (median (ng mL-1 ) [confidence interval] 64 [29-125] vs. 83 [35-147], 9 [2-15] vs. 12 [4-18] and 171 [56-245] vs. 201 [66-350], respectively) but levels of Bb fragment were unchanged. There were no correlations between rivaroxaban levels and complement activation markers. Conclusions APS patients with previous VTE on warfarin exhibit increased complement activation, which is likely to occur via the classical pathway and is decreased by rivaroxaban administration. Rivaroxaban may therefore potentially provide an additional benefit to its anticoagulant effect in this patient group by limiting complement activation.

Interactions between rivaroxaban and antiphospholipid antibodies in thrombotic antiphospholipid syndrome

INTRODUCTION

Rivaroxaban can affect lupus anticoagulant (LA) testing and antiphospholipid antibodies (aPL) may interfere with the anticoagulant action of rivaroxaban.

AIMS

To establish the influence of rivaroxaban on LA detection and of aPL on the anticoagulant action of rivaroxaban.

METHODS

Rivaroxaban and 52 IgG preparations (20 LA+ve, 12 LA-ve thrombotic antiphospholipid syndrome [APS] patients, and 20 normal controls [NC]) were spiked into pooled normal plasma (PNP) for relevant studies. LA detection was also studied in APS patients receiving rivaroxaban 20 mg once daily.

RESULTS

In vitro spiking of samples with rivaroxaban showed no false positive LA with Textarin time, Taipan venom time/Ecarin clotting time (TVT/ECT), dilute prothrombin time (dPT) and in-house dilute Russell's viper venom time (DRVVT), but false positives in the majority of NC and LA negative IgG with two commercial DRVVT reagents at 250 ng/mL but not 50 ng/mL rivaroxaban. Ex vivo studies: six LA+ve patients on rivaroxaban remained LA positive with TVT/ECT and DRVVT at peak (162-278 ng/mL) and trough (30-85 ng/mL) rivaroxaban levels. Six LA-ve patients became (apparently) LA+ve with two DRVVT reagents (test/confirm ratio median [confidence interval], 1.6 [1.3-1.8], 1.6 [1.4-1.9]) but not with TVT/ECT at peak rivaroxaban levels, and remained LA-ve with both DRVVT reagents and TVT/ECT at trough levels. aPL positive IgG spiking of PNP had no effect on rivaroxaban's anticoagulant action on thrombin generation or rivaroxaban anti-Xa levels.

CONCLUSIONS

The TVT/ECT ratio and Textarin time were not affected even at peak rivaroxaban levels, enabling detection of LA ex vivo. aPL had no effects on rivaroxaban's anticoagulant action in vitro.

Protective effects of non-anticoagulant activated protein C variant (D36A/L38D/A39V) in a murine model of ischaemic stroke

Ischaemic stroke is caused by occlusive thrombi in the cerebral vasculature. Although tissue-plasminogen activator (tPA) can be administered as thrombolytic therapy, it has major limitations, which include disruption of the blood-brain barrier and an increased risk of bleeding. Treatments that prevent or limit such deleterious effects could be of major clinical importance. Activated protein C (APC) is a natural anticoagulant that regulates thrombin generation, but also confers endothelial cytoprotective effects and improved endothelial barrier function mediated through its cell signalling properties. In murine models of stroke, although APC can limit the deleterious effects of tPA due to its cell signalling function, its anticoagulant actions can further elevate the risk of bleeding. Thus, APC variants such as APC(5A), APC(Ca-ins) and APC(36-39) with reduced anticoagulant, but normal signalling function may have therapeutic benefit. Human and murine protein C (5A), (Ca-ins) and (36-39) variants were expressed and characterised. All protein C variants were secreted normally, but 5-20% of the protein C (Ca-ins) variants were secreted as disulphide-linked dimers. Thrombin generation assays suggested reductions in anticoagulant function of 50- to 57-fold for APC(36-39), 22- to 27-fold for APC(Ca-ins) and 14- to 17-fold for APC(5A). Interestingly, whereas human wt APC, APC(36-39) and APC(Ca-ins) were inhibited similarly by protein C inhibitor (t_½ - 33 to 39 mins), APC(5A) was inactivated ~9-fold faster (t_½ - 4 mins). Using the murine middle cerebral artery occlusion ischaemia/repurfusion injury model, in combination with tPA, APC(36-39), which cannot be enhanced by its cofactor protein S, significantly improved neurological scores, reduced cerebral infarct area by ~50% and reduced oedema ratio. APC(36-39) also significantly reduced bleeding in the brain induced by administration of tPA, whereas wt APC did not. If our data can be extrapolated to clinical settings, then APC(36-39) could represent a feasible adjunctive therapy for ischaemic stroke.

Rivaroxaban and warfarin achieve effective anticoagulation, as assessed by inhibition of TG and in-vivo markers of coagulation activation, in patients with venous thromboembolism

INTRODUCTION

Rivaroxaban is non-inferior to warfarin for the treatment of venous thromboembolism, with regard to clinical efficacy and safety. The ex-vivo effects of warfarin versus therapeutic dose rivaroxaban on in-vivo markers of coagulation activation and thrombin generation remain undefined. The aim of this study was to compare the effects of warfarin and therapeutic dose rivaroxaban on ex-vivo thrombin generation (TG), and the in-vivo markers of coagulation activation, prothrombin fragment 1.2 (F1.2), thrombin-antithrombin complex (TAT), and D-dimer.

METHODS

Eighty-five patients with venous thromboembolism were studied, 45 on warfarin, target INR 2.5 and 40 on rivaroxaban 20mg once daily.

RESULTS

Anticoagulation was in therapeutic range in 71% (32/45) warfarin and 65% (26/40) rivaroxaban treated patients. 8 patients on warfarin and 9 patients on rivaroxaban had subtherapeutic INR and rivaroxaban levels respectively. Both rivaroxaban and warfarin reduced endogenous thrombin potential (ETP) and peak thrombin, and prolonged lag time and time to peak, compared to normal controls (p<0.0001). The lag time and time to peak TG were longer, and peak thrombin was lower in patients receiving rivaroxaban (p<0.0001) compared with warfarin, although warfarin-treated patients had lower ETP (p=0.0008). In-vivo coagulation activation markers were within the normal ranges in all rivaroxaban-treated patients (including those with levels considered to be subtherapeutic) and in 37/45 warfarin-treated patients who had an INR≥2.0. The warfarin-treated patients with subtherapeutic INRs exhibited slightly raised F1.2 and/or TAT.

CONCLUSION

In conclusion, both rivaroxaban and warfarin provided effective anticoagulation, as assessed by inhibition of TG and makers of in-vivo coagulation activation.

Anti-protein C antibodies are associated with resistance to endogenous protein C activation and a severe thrombotic phenotype in antiphospholipid syndrome

BACKGROUND

Antiphospholipid antibodies may interfere with the anticoagulant activity of activated protein C (APC) to induce acquired APC resistance (APCr).

AIMS

To investigate the frequency and characteristics of APCr by using recombinant human APC (rhAPC) and endogenous protein C activation in antiphospholipid syndrome (APS).

METHODS

APCr was assessed in APS and non-APS venous thromboembolism (VTE) patients on warfarin and normal controls with rhAPC or Protac by thrombin generation. IgG anti-protein C and anti-protein S antibodies and avidity were assessed by ELISA.

RESULTS

APS patients showed greater resistance to both rhAPC and Protac than non-APS patients and normal controls (median normalized endogenous thrombin potential inhibition): APS patients with rhAPC, 81.3% (95% confidence interval [CI] 75.2-88.3%; non-APS patients with rhAPC, 97.7% (95% CI 93.6-101.8%; APS patients with Protac, 66.0% (95% CI 59.5-72.6%); and non-APS patients with Protac, 80.7 (95% CI 74.2-87.2%). APS patients also had a higher frequency and higher levels of anti-protein C antibodies, with 60% (15/25) high-avidity antibodies. High-avidity anti-protein C antibodies were associated with greater APCr and with a severe thrombotic phenotype (defined as the development of recurrent VTE while patients were receiving therapeutic anticoagulation or both venous and arterial thrombosis). Twelve of 15 (80%) patients with high-avidity anti-protein C antibodies were classified as APS category I.

CONCLUSION

Thrombotic APS patients showed greater APCr to both rhAPC and activation of endogenous protein C by Protac. High-avidity anti-protein C antibodies, associated with greater APCr, may provide a marker for a severe thrombotic phenotype in APS. However, in patients with category I APS, it remains to be established whether anti-protein C or anti-β2 -glycoprotein I antibodies are responsible for APCr.

Determination of APTT factor sensitivity--the misguiding guideline

Introduction

The Clinical and Laboratory Standards Institute (CLSI) has produced a guideline detailing how to determine the activated partial thromboplastin time’s (APTT) sensitivity to clotting factor deficiencies, by mixing normal and deficient plasmas. Using the guideline, we determined the factor sensitivity of two APTT reagents.

Methods

APTTs were performed using Actin FS and Actin FSL on a Sysmex CS-5100 analyser. The quality of factor-deficient and reference plasmas from three commercial sources was assessed by assaying each of the clotting factors within the plasmas and by performing thrombin generation tests (TGT).

Results

Testing samples from 50 normal healthy subjects gave a two-standard deviation range of 21.8–29.2 s for Actin FS and 23.5–29.3 s for Actin FSL. The upper limits of these ranges were subsequently used to determine APTT factor sensitivity. Assay of factor levels within the deficient plasmas demonstrated that they were specifically deficient in a single factor, with most other factors in the range 50–150 iu/dL (Technoclone factor VII-deficient plasma has 26 iu/dL factor IX). APTTs performed on mixtures of normal and deficient plasmas gave diverse sensitivity to factor deficiencies dependent on the sources of deficient plasma. TGT studies on the deficient plasmas revealed that the potential to generate thrombin was not solely associated with the levels of their component clotting factors.

Conclusion

Determination of APTT factor sensitivity in accordance with the CLSI guideline can give inconsistent and misleading results.

Biopsy forceps is inadequate for the resection of diminutive polyps

BACKGROUND AND STUDY AIMS

Cold biopsy forceps polypectomy (CBP) is often used for the removal of diminutive polyps. The efficacy of the technique has not been thoroughly assessed. The aim of this study was to prospectively assess the efficacy of CBP for removing diminutive polyps.

PATIENTS AND METHODS

This was a prospective study from St Vincent's Hospital, a tertiary referral hospital in Melbourne, Australia. A total of 143 patients were screened and 52 patients with ≥ 1 diminutive polyps were enrolled. CBP was used to resect diminutive polyps until no polyp tissue was visible. The polyp base was then resected using endoscopic mucosal resection (EMR) with a 1 - 2-mm margin. The CBP and EMR samples were compared to assess completeness of the resection.

RESULTS

Overall 39 % (21 / 54) of diminutive polyps were completely resected using CBP. After binary logistic regression analysis, polyp histology was found to be predictive of resection, with complete resection of 62 % (13 / 21) for adenomas and 24 % (8 / 33) for hyperplastic polyps (odds ratio 5.1; P = 0.008). The size and number of bites taken with the forceps were not predictive of complete response.

CONCLUSIONS

Within the limitations of a modest sample size, CBP appears to be inadequate treatment for the removal of diminutive polyps.

Change in serum lipids after acute coronary syndromes: secondary analysis of SPACE ROCKET study data and a comparative literature review

BACKGROUND

It has long been an accepted belief that serum cholesterol significantly falls after myocardial infarction and that a return to pre-event levels takes approximately 3 months. The magnitude and clinical significance of this fall has recently been challenged.

METHODS

In the Secondary Prevention of Acute Coronary Events-Reduction Of Cholesterol to Key European Targets (SPACE ROCKET) trial, we measured serum lipids of individuals on day 1 and between days 2 and 4 after acute myocardial infarction (AMI). Second, we performed a thorough literature review and compared all studies reporting data on absolute changes in lipids immediately after AMI, using weighted means.

RESULTS

Of 1263 SPACE ROCKET participants, 128 had paired lipid measurements where both samples had been measured using identical methods at baseline and on days 2-4 after AMI. The mean lowering in total cholesterol between day 1 and day 2-4 was 0.71 mmol/L (95% CI 0.58-0.84; P < 0.0001) and in triglycerides was 0.10 mmol/L (-0.14-0.33; P = 0.405). A total of 25 papers showing absolute lipid changes post-AMI were identified. The combined data demonstrated a mean fall in total cholesterol of 9% to 11% from baseline over days 3-14 post-AMI, whereas for triglycerides, there was a rise of 18% from baseline to between day 9 and 12 weeks.

CONCLUSIONS

After a secondary analysis of SPACE ROCKET data and a comparison of previously published data, we report a 10% fall in total cholesterol after AMI-a difference that is of high clinical significance. Consequently, measurement of serum lipids in patients with AMI should be performed within the first hours after presentation.

Hepatic metabolism and transporter gene variants enhance response to rosuvastatin in patients with acute myocardial infarction: the GEOSTAT-1 Study

BACKGROUND

Pharmacogenetics aims to maximize benefits and minimize risks of drug treatment. Our objectives were to examine the influence of common variants of hepatic metabolism and transporter genes on the lipid-lowering response to statin therapy.

METHODS AND RESULTS

The Genetic Effects On STATins (GEOSTAT-1) Study was a genetic substudy of Secondary Prevention of Acute Coronary Events-Reduction of Cholesterol to Key European Targets (SPACE ROCKET) (a randomized, controlled trial comparing 40 mg of simvastatin and 10 mg of rosuvastatin) that recruited 601 patients after myocardial infarction. We genotyped the following functional single nucleotide polymorphisms in the genes coding for the cytochrome P450 (CYP) metabolic enzymes, CYP2C9*2 (430C>T), CYP2C9*3 (1075A>C), CYP2C19*2 (681G>A), CYP3A5*1 (6986A>G), and hepatic influx and efflux transporters SLCO1B1 (521T>C) and breast cancer resistance protein (BCRP; 421C>A). We assessed 3-month LDL cholesterol levels and the proportion of patients reaching the current LDL cholesterol target of <70 mg/dL (<1.81 mmol/L). An enhanced response to rosuvastatin was seen for patients with variant genotypes of either CYP3A5 (P=0.006) or BCRP (P=0.010). Furthermore, multivariate logistic-regression analysis revealed that patients with at least 1 variant CYP3A5 and/or BCRP allele (n=186) were more likely to achieve the LDL cholesterol target (odds ratio: 2.289; 95% CI: 1.157, 4.527; P=0.017; rosuvastatin 54.0% to target vs simvastatin 33.7%). There were no differences for patients with variants of CYP2C9, CYP2C19, or SLCO1B1 in comparison with their respective wild types, nor were differential effects on statin response seen for patients with the most common genotypes for CYP3A5 and BCRP (n=415; odds ratio: 1.207; 95% CI: 0.768, 1.899; P=0.415).

CONCLUSION

The LDL cholesterol target was achieved more frequently for the 1 in 3 patients with CYP3A5 and/or BCRP variant genotypes when prescribed rosuvastatin 10 mg, compared with simvastatin 40 mg. Clinical Trial Registration- URL: http://isrctn.org. Unique identifier: ISRCTN 89508434.

An Interesting Case of Recurrent Small Bowel Obstruction

Sclerosing mesenteritis is associated with a spectrum of diseases which include mesenteric lipodystrophy and mesenteric panniculitis. This inflammatory and fibrosing disorder can affect the small and large bowel wall and mesenteric vessels by exerting a mass effect. The following case highlights the difficulties with diagnosing and managing this unusual disease. A 64-year-old man presented with acute central abdominal pain, radiating to his back, and profuse vomiting. He was diagnosed clinically with small bowel obstruction. He had had an episode of small bowel obstruction 6 years earlier. At this time, he underwent an exploratory laparotomy, and a mass was identified in the small bowel mesentery. The features were thought to be in keeping with sclerosing mesenteritis. He had a dramatically favourable response to the initiation of prednisolone. He continued to be well and asymptomatic for a further 5 years on long-term maintenance low-dose steroids and 6-mercaptopurine. He re-presented in 2009 (six years after initial presentation) with very severe acute abdominal pain and vomiting. He had no recent change in weight or appetite, and had not had time off work. He underwent a second laparotomy and the tissue diagnosis was of metastatic carcinoid tumour involving the small bowel mesentery. This is the first case to our knowledge where sclerosing mesenteritis has been confirmed histologically on biopsy and then subsequently diagnosed with histologically proven carcinoid tumour. For this particular reason it must be always remembered that sclerosing mesenteritis is a 'pathological' and not a radiological diagnosis and that a large proportion of cases are associated with neoplasia.

Mutations in BMP4 cause eye, brain, and digit developmental anomalies: overlap between the BMP4 and hedgehog signaling pathways

Developmental ocular malformations, including anophthalmia-microphthalmia (AM), are heterogeneous disorders with frequent sporadic or non-Mendelian inheritance. Recurrent interstitial deletions of 14q22-q23 have been associated with AM, sometimes with poly/syndactyly and hypopituitarism. We identify two further cases of AM (one with associated pituitary anomalies) with a 14q22-q23 deletion. Using a positional candidate gene approach, we analyzed the BMP4 (Bone Morphogenetic Protein-4) gene and identified a frameshift mutation (c.226del2, p.S76fs104X) that segregated with AM, retinal dystrophy, myopia, brain anomalies, and polydactyly in a family and a nonconservative missense mutation (c.278A-->G, p.E93G) in a highly conserved base in another family. MR imaging and tractography in the c.226del2 proband revealed a primary brain developmental disorder affecting thalamostriatal and callosal pathways, also present in the affected grandmother. Using in situ hybridization in human embryos, we demonstrate expression of BMP4 in optic vesicle, developing retina and lens, pituitary region, and digits strongly supporting BMP4 as a causative gene for AM, pituitary, and poly/syndactyly. Because BMP4 interacts with HH signaling genes in animals, we evaluated gene expression in human embryos and demonstrate cotemporal and cospatial expression of BMP4 and HH signaling genes. We also identified four cases, some of whom had retinal dystrophy, with "low-penetrant" mutations in both BMP4 and HH signaling genes: SHH (Sonic Hedgehog) or PTCH1 (Patched). We propose that BMP4 is a major gene for AM and/or retinal dystrophy and brain anomalies and may be a candidate gene for myopia and poly/syndactyly. Our finding of low-penetrant variants in BMP4 and HH signaling partners is suggestive of an interaction between the two pathways in humans.