Correction of thrombocytopenia with aspirin in the primary antiphospholipid syndrome

Thrombocytopenia in primary antiphospholipid syndrome: association with prognosis and clinical implications

OBJECTIVES

Thrombocytopenia, a frequent clinical manifestation in patients with APS, could be an independent predictor of recurrent thrombotic, obstetric and severe extracriteria events.

METHODS

This single-centre prospective study enrolled 218 consecutive patients diagnosed with primary APS between 2010 and 2021. Thrombocytopenia was defined as a platelet count less than 100 × 109/L.

RESULTS

Our cohort included 74 (33.94%) patients with thrombocytopenia and 144 patients with a continuous normal platelet count. Comparison of baseline characteristics indicated that patients with thrombocytopenia had more visceral venous thromboses [10 (13.51%) vs 5(3.47%); P = 0.009] and extracriteria manifestations [mainly haemolytic anaemia; 20 (27.03%) vs 17 (11.81%); P = 0.007]. Hypocomplementemia was more likely among patients with thrombocytopenia [19 (25.68%) vs 16 (11.11%); P = 0.01]. The presence of aCL-IgG/IgM, anti-β2-glycoprotein I and lupus anticoagulant were more frequently detected in patients with thrombocytopenia. In survival analysis, thrombotic, obstetric and severe extracriteria survival rates were significantly worse in patients with thrombocytopenia. In multivariate Cox regression, thrombocytopenia was an independent risk factor for all endpoint events, including thrombotic events [hazard ratio (HR) 2.93 (95% CI 1.31, 6.56), P = 0.009], pregnancy morbidity [HR 8.00 (95% CI 2.43, 26.37), P = 0.0006] and severe extracriteria events [HR 15.27 (95% CI 1.85, 125.98), P = 0.01].

CONCLUSION

Thrombocytopenia could identify primary APS patients at high risk of developing thrombotic events, pregnancy morbidity and severe extracriteria events.

Cardiac and vascular features of arterial and venous primary antiphospholipid syndrome. The multicenter ATHERO-APS study

BACKGROUND

Patients with primary antiphospholipid syndrome (PAPS) may suffer from venous and/or arterial thrombosis, but studies addressing eventual clinical and laboratory features that may discriminate between arterial thromboembolism (ATE) from venous thromboembolism (VTE) have been poorly addressed.

METHODS

Cross sectional comparison of baseline characteristics of 100 patients enrolled in the multi center ATHERO-APS cohort study; patients with previous ATE and VTE were compared with regards to clinical and biochemical variables as well as to echocardiographic features and ankle-brachial index (ABI) measured at enrolment.

RESULTS

Mean age of patients was 51 years, 72 were women. 60 patients suffered VTE and 40 ATE. Compared to VTE, ATE patients displayed a higher prevalence of hypertension (43.3% vs. 65%, p = 0.034) and diabetes (3.3% vs. 17.5%, p = 0.015). Mean concentration of inflammation and complement activation markers were similar between the two groups as well as autoantibodies titres; mean D-dimer concentration was greater in VTE patients (184 ng/ml vs. 347 ng/ml; p = 0.024) whereas mean platelet count was greater in ATE patients (263 × 10⁹/L vs 216 × 10⁹/L, p = 0.044). By multivariable logistic regression analysis, adjusted for age, sex, hypertension and diabetes, ABI ≤ 0.9 (OR: 3.4; p = 0.041) and left atrial enlargement (OR: 3.5; p = 0.035) were associated with a history of ATE. ATE patients had a higher prevalence of ABI <0.9 (32.5% vs 10% p = 0.005) than VTE patients. At logistic regression analysis, IgG aCL >120 GPL U/ml was associated with an ABI ≤0.9 (OR: 5; p = 0.023) after adjustment for age and sex.

CONCLUSION

Clinical, laboratory and cardiovascular variables distinguish arterial from venous APS patients, amongst which the ABI and left atrial enlargement. Implications for these two distinct clinical phenotypes of APS patients need further investigation.

Cryptic conspirators: a conversation about thrombocytopenia and antiphospholipid syndrome

Purpose of review

Although antiphospholipid syndrome (APS) is best known for conveying increased risk of thrombotic events and pregnancy morbidity, thrombocytopenia is also recognized as a common association. In this review, we will explore the relationship between thrombocytopenia and APS, highlighting our evolving understanding – and persistent knowledge gaps – through clinically oriented questions and answers.

Recent findings

A history of thrombocytopenia likely portends a more severe APS phenotype (including increased risk of thrombosis). Although the pathophysiology underlying thrombocytopenia in APS has yet to be definitively revealed, mechanisms that play a role (at least in subsets of patients) include: immune thrombocytopenic purpura/ITP-like autoantibodies against platelet glycoproteins; antiphospholipid antibody (aPL)-mediated platelet activation and consumption; and potentially life threatening thrombotic microangiopathy. Although thrombocytopenia is often ‘mild’ in APS (and therefore, may not require specific therapy), there are causes of acute-onset thrombocytopenia that mandate emergent work-up and treatment. When APS-related thrombocytopenia does require therapy, the approach must be individualized (requiring an understanding of pathophysiology in the particular APS patient). For patients with ITP-like disease, rituximab is emerging as a popular approach to treatment; in contrast, there are hints that thrombopoietin mimetics may be associated with elevated thrombotic risk.

Summary

Thrombocytopenia is common in APS, and is likely associated with more severe disease. Improved understanding of thrombocytopenia in APS has the potential to improve risk stratification, reveal novel aspects of APS pathophysiology, and lead to treatments that are more individualized and holistic.

Clinical profiles and risk assessment in patients with antiphospholipid antibodies

INTRODUCTION

Antiphospholipid syndrome (APS) is an acquired autoimmune thrombophilia associated with the presence of persistent antiphospholipid antibodies (aPL). Owing to recent studies, not only APS patients but also incidentally-identified, asymptomatic aPL carriers are able to be stratified in terms of the risk of future thrombotic events, according to the variety and the titer of positive aPL tests and to the non-thrombotic, aPL-associated clinical manifestations. Areas covered: Here, we critically review (1) criteria manifestations of APS, (2) non-criteria manifestations of APS, (3) risk assessment in patients with APS and in aPL carriers, and (4) the potential role of primary thrombosis prophylaxis in aPL carriers. In addition, we discuss what we are currently able to do and what we need to do in the future for primary prophylaxis against a first thrombotic event. Expert commentary: We suggest a comprehensive algorithm to stratify thrombotic risk in aPL carriers, including criteria aPL, non-criteria aPL, their scoring systems, and non-criteria manifestations. However, further studies, particularly prospective randomized controlled trials, are highly warranted to establish an effective and tolerable treatment regimen for high risk aPL carriers.

Thrombotic risk stratification by platelet count in patients with antiphospholipid antibodies: a longitudinal study

Essentials Thrombotic risk stratification is an unmet need in antiphospholipid antibody carriers. Platelet count and antiphospholipid score (aPL-S) were combined to predict thrombotic events. Patients with high aPL-S are at high thrombotic risk regardless of platelet count. If platelet count is low, patients with low aPL-S are also on high thrombotic risk.

SUMMARY

Background Thrombocytopenia is a non-criteria clinical manifestation of antiphospholipid syndrome. However, it remains to be elucidated whether thrombocytopenia increases thrombotic risk in antiphospholipid antibody (aPL) carriers. Objectives To investigate the impact of platelet count in terms of predicting thrombotic events in aPL carriers, and to stratify the thrombotic risk by combining platelet count and antiphospholipid score (aPL-S), which represents a quantification of aPL varieties and titers. Patients/methods A single-center, retrospective, longitudinal study comprising 953 consecutive patients who were suspected of having autoimmune disease between January 2002 and December 2006 was performed. Low platelet count was defined as a count of < 150 × 103 μL-1 at the time of aPL testing. Results A negative correlation was observed between aPL-S and platelet count (r = - 0.2477). Among aPL-positive patients, those with a low platelet count developed thrombosis more frequently than those without (hazard ratio [HR] 2.95, 95% confidence interval [CI] 1.11-7.88). Among aPL-negative patients, no difference was found in the predictive value of thrombosis regardless of platelet count. Patients with aPLs were further divided into two subgroups according to aPL-S. Among low-aPL-S patients, those with low platelet counts developed thrombosis more frequently than those without (HR 3.44, 95% CI 1.05-11.2). In contrast, high-aPL-S patients developed thrombosis frequently regardless of platelet count. Conclusions aPL carriers with low platelet counts are at high risk of developing thrombosis. In particular, 'low-aPL-S carriers' may be stratified by platelet count in terms of predicting future thrombotic events.

Antiphospholipid antibody associated thrombocytopenia and the paradoxical risk of thrombosis

The pathogenesis of thrombocytopenia in patients with antiphospholipid syndrome (APS) is heterogeneous. Patients with antiphospholipid antibodies (aPL) and thrombocytopenia in the absence of clinical manifestations of APS will be diagnosed and treated as idiopathic thrombocytopenic purpura. However, the presence of aPL places those individuals at particular risk for developing both bleeding and thrombotic complications. Therefore, we propose the inclusion of such patients in the subgroup ‘aPL-associated thrombocytopenia’. More attention should be devoted to this subgroup of patients to elucidate the role of aPL in the development of thrombocytopenia and to facilitate the adequate monitoring of its potential thrombotic risk.

Thrombotic risk in patients with immune thrombocytopenia and its association with antiphospholipid antibodies

Patients with immune thrombocytopenia (ITP) paradoxically have an increased risk of thrombosis. The presence of antiphospholipid antibodies (aPL) has been observed in a substantial proportion of ITP patients, but its clinical significance remains to be established. This study retrospectively investigated the prevalence and clinical significance of aPL in ITP patients and assessed the risk factors for thrombosis. One hundred and sixty-five subjects with ITP were included in the study and followed for a mean period of 63·4 months. Sixty-nine (41·6%) patients were positive for aPL at diagnosis, and their clinical characteristics and course of ITP were not different from those of aPL-negative patients. Twenty-one (12·7%) patients developed a thrombotic event during follow-up and the cumulative incidence rate ratio of aPL-positive to aPL-negative patients for thromboembolism was 3·15 [95% confidence interval (CI) 1·21-8·17] after adjusting for confounding factors. Lupus anticoagulant and hypertension were identified by Cox regression analysis as independent risk factors for thrombosis [hazard ratio (HR) 4·1, 95% CI 1·4-11·9, P = 0·009 and HR 5·6, 95% CI 1·9-15·8, P = 0·001, respectively]. Our results showed that a substantial proportion of ITP patients were aPL-positive, and that lupus anticoagulant and hypertension were independent risk factors for thrombosis. Detection of aPL can provide useful information for identifying patients at high-risk for developing thrombosis.

Therapeutic approaches to secondary immune thrombocytopenic purpura

Secondary thrombocytopenia is similar to primary or idiopathic thrombocytopenia (ITP) in that it is characterized by reduced platelet production or increased platelet destruction resulting in platelet levels<60,000/microL. Thrombocytopenia can occur from secondary causes associated with chronic disorders or with disturbed immune function due to chronic infections, lymphoproliferative and myeloproliferative disorders, pregnancy, or autoimmune disorders. Diagnosis of secondary ITP in some cases is complex, and the thrombocytopenia can often be resolved by treating the underlying disorder to the extent this is possible. In most cases, treatment is focused on reducing platelet destruction, but, in some cases, treatment may also be directed at stimulating platelet production. The most problematic cases of thrombocytopenia may be seen in pregnant women. This review will address various agents and their utility in treating ITP from secondary causes; in addition, thrombocytopenia in pregnancy, ITP in immunodeficiency conditions, and drug-induced thrombocytopenia will be discussed. Unlike primary ITP, treatment often must be tailored to the specific circumstance underlying the secondary ITP, even if the condition itself is incurable.

Pathobiology of secondary immune thrombocytopenia

Primary immune thrombocytopenic purpura (ITP) remains a diagnosis of exclusion both from nonimmune causes of thrombocytopenia and immune thrombocytopenia that develops in the context of other disorders (secondary immune thrombocytopenia). The pathobiology, natural history, and response to therapy of the diverse causes of secondary ITP differ from each other and from primary ITP, so accurate diagnosis is essential. Immune thrombocytopenia can be secondary to medications or to a concurrent disease, such as an autoimmune condition (eg, systemic lupus erythematosus [SLE], antiphospholipid antibody syndrome [APS], immune thyroid disease, or Evans syndrome), a lymphoproliferative disease (eg, chronic lymphocytic leukemia or large granular T-lymphocyte lymphocytic leukemia), or chronic infection, eg, with Helicobacter pylori, human immunodeficiency virus (HIV), or hepatitis C virus (HCV). Response to infection may generate antibodies that cross-react with platelet antigens (HIV, H pylori) or immune complexes that bind to platelet Fcγ receptors (HCV), and platelet production may be impaired by infection of megakaryocyte (MK) bone marrow–dependent progenitor cells (HCV and HIV), decreased production of thrombopoietin (TPO), and splenic sequestration of platelets secondary to portal hypertension (HCV). Sudden and severe onset of thrombocytopenia has been observed in children after vaccination for measles, mumps, and rubella or natural viral infections, including Epstein-Barr virus, cytomegalovirus, and varicella zoster virus. This thrombocytopenia may be caused by cross-reacting antibodies and closely mimics acute ITP of childhood. Proper diagnosis and treatment of the underlying disorder, where necessary, play an important role in patient management.