Thrombin Generation Assay in Antiphospholipid Antibodies Positive Subjects as a Personalized Thrombotic Risk Assessment: State of the Art and Perspectives.

PURPOSE OF THE REVIEW: Thrombotic risk assessment in antiphospholipid positive (aPL +) subjects is a major challenge, and the study of in vitro thrombin generation (thrombin generation assays (TGA)) could provide useful information. Activated protein C (APC) sensitivity is involved in thrombotic events in antiphospholipid syndrome patients. We summarized methods used to assess APC sensitivity with TGA and evaluated the prognostic role of APC resistance through literature search. RECENT FINDINGS: APC resistance induced by aPL is a complex pathway. Several cross-sectional studies assessed APC sensitivity to understand thrombotic event mechanisms in aPL + subjects. Only one prospective cohort had investigated the prognostic impact of APC resistance in aPL + subjects, with a positive and significant correlation between APC sensitivity and the risk of thrombosis during the follow up (hazard ratio, 6.07 [95% CI, 1.69-21.87]). APC resistance assessed with TGA could be associated with thrombotic events in aPL + subjects.

Determination of four homogeneous subgroups of patients with antiphospholipid syndrome: a cluster analysis based on 509 cases.

OBJECTIVE: APS is a heterogeneous disease with different phenotypes. Using an unsupervised hierarchical cluster analysis, we aimed to determine distinct homogeneous phenotypes among APS patients. METHODS: We performed an observational, retrospective study of APS patients enrolled in the French multicentre 'APS and SLE' registry who met the Sydney classification criteria. The clustering process involved an unsupervised multiple correspondence analysis followed by a hierarchical ascendant clustering analysis; it used 27 variables selected to cover a broad range of APS clinical and laboratory manifestations. RESULTS: These analyses included 509 patients, mainly women (77.8%). Mean (s.d.) age at APS diagnosis was 36.2 (14.6) years, and mean follow-up since diagnosis 10.3 (8.5) years. This hierarchical classification cluster analysis yielded four homogeneous groups of patients: cluster 1, mostly with venous thromboembolism without any associated autoimmune disease; cluster 2, older, lowest proportion of women, history of arterial events, and/or with migraines, arterial hypertension, diabetes mellitus, or dyslipidaemia; cluster 3, younger, highest proportion of women, associated SLE or other autoimmune diseases, and a history of venous thromboembolism or pregnancy morbidity; and cluster 4, mainly with a history of catastrophic antiphospholipid syndrome, aPL-associated nephropathy, and pregnancy morbidity, with frequent triple positivity and more deaths (16.7%). CONCLUSIONS: Our study applied an unsupervised clustering method to distinguish four homogeneous APS patient subgroups that were predominantly venous; arterial; associated with SLE or another autoimmune disease; and arterial microthrombotic. Heterogeneous pathophysiological mechanisms may explain these findings.

A new pro-thrombotic mechanism of neutrophil extracellular traps in antiphospholipid syndrome: impact on activated protein C resistance.

OBJECTIVES: In APS, precise evaluation of thrombotic risk is a major challenge. Different players, such as activated protein C (APC) resistance or neutrophil extracellular traps (NETs) contribute to the risk of thrombosis. Nevertheless, no study has investigated the interaction between these actors. The main objective of this study was to investigate the relation between NETs and APC resistance. METHODS: We designed a cross-sectional study including APS/antiphospholipid antibodies (aPL) patients and patients with autoimmune diseases (AID). We performed thrombin generation tests without and with APC to determine APC resistance. To evaluate circulating NETs, we measured plasma levels of MPO-DNA complexes and cell-free DNA with ELISA. RESULTS: We recruited 117 patients with definite APS/aPL or AID. We found a positive correlation between NETs and APC resistance, in APS patients and specifically in patients with high thrombotic risk, displaying LA or positivity of all three aPL tests (triple+), or anti-domain I IgG (aDI+). All these patient subgroups had increased NETs concentrations and APC resistance. As the risk profile for thrombosis increased, the relationship between NETs and APC resistance was stronger. CONCLUSION: We have shown that NETs participate in the hypercoagulable state of APS patients by contributing to APC resistance, in particular in high-risk patients. In these most at-risk patients, a targeted action on NETs could reduce APC resistance and constitute a new therapeutic approach in the treatment of APS patients in addition to antithrombotic therapy.

Efficacy and safety of TNF-α antagonists and tocilizumab in Takayasu arteritis: multicentre retrospective study of 209 patients.

OBJECTIVE: To assess the safety and the efficacy of TNF-α antagonists and tocilizumab in patients with Takayasu arteritis (TAK). METHODS: A total of 209 patients with TAK [median age 29 years (interquartile range 7-62)], 186 (89%) females] were included. They received either TNF-α antagonists [n = 132 (63%) with 172 lines; infliximab (n = 109), adalimumab (n = 45), golimumab (n = 8), certolizumab (n = 6) and etanercept (n = 5)] or tocilizumab [n = 77 (37%) with 121 lines; i.v. and s.c. in 95 and 26 cases, respectively]. RESULTS: A complete response at 6 months was evidenced in 101/152 (66%) patients on TNF-α antagonists and 75/107 (70%) patients on tocilizumab. Age ≥30 years [odds ratio 2.09 (95% CI 1.09, 3.99)] was associated with complete response, whereas vascular signs [OR 0.26 (95% CI 0.1, 0.65)], baseline prednisone ≥20 mg/day [OR 0.51 (95% CI 0.28, 0.93)] were negatively associated with the complete response to TNF-α antagonists or tocilizumab. During a median follow-up of 36 months, 103 relapses were noted. Supra-aortic branches and thoracic aorta involvement [HR 2.44 (95% CI 1.06, 5.65) and 3.66 (1.18, 11.4), respectively] and systemic signs at baseline [HR 2.01 (95% CI 1.30, 3.11)] were significantly associated with relapse. The cumulative incidence of treatment discontinuation and relapse were similar in TNF-α antagonists and tocilizumab. Fifty-eight (20%) adverse effects occurred on biologic targeted therapies [37 (21%) on TNF-α antagonists and 21 (17%) on tocilizumab (P = 0.4), respectively]. CONCLUSION: This large multicentre study shows high efficacy of biologic targeted treatments in refractory TAK. Efficacy, relapse and drug retention rate were equivalent with TNF-α antagonists and tocilizumab.

Antiphospholipid syndrome in patients over 65 years: A comparative study of clinical and biological features and thrombotic relapses.

OBJECTIVE: The aim of the study was to describe clinical and biological characteristics and thrombotic relapses of patients diagnosed with antiphospholipid syndrome (APS) after the age of 65 years, in comparison with patients diagnosed with APS before 65. METHODS: This retrospective multicenter study was performed to 2005 from 2017 and included patients diagnosed with APS after the age of 65 years, in accordance with Sydney criteria. We compared these patients with APS patients diagnosed before the age of 65 years, and with control thrombotic patients older than 65 years. RESULTS: Fifty-eight APS patients over the age of 65 years were compared to 127 APS patients aged less than 65 and to 58 controls. In elderly APS versus younger APS, there was a male predominance (58.6% vs 36.2% p = .001); myocardial infarction and lower limb deep vein thrombosis (LLDVT) were more frequent in elderly, respectively, 12.1% versus 1.6% (p = .005), and 44.8% versus 29.9% (p = .048). Anticardiolipin antibody (aCL) IgM was more frequently found in old patients compared to younger patients (33.9% vs 18.1%, p = .02), contrary to lupus anticoagulant (LAC) (52.8% vs 66.9%, p = .02). Older patients were more often diagnosed with single positive APS (82.8% vs 59.8% p = .002). The thrombotic relapse free survival was lower in elderly APS patients (p = .044) compared to younger APS. Elderly APS patients had more recurrent arterial and venous thrombosis (p = .03) and had poorer overall survival (p = .004) than elderly controls. CONCLUSION: In this study, APS was different in patients aged more than 65 years, with a male predominance and more myocardial infarctions and LLDVT at diagnosis. Single antiphopholipid positivity and aCL IgM were more frequent in older patients. Older patient with APS had more thrombotic recurrence during follow-up. Compared to elderly controls, elderly APS patients had more thrombosis recurrences and poorer survival.

Risk of livedo with antiphospholipid antibodies in patients with systemic lupus erythematosus: A systematic review and meta-analysis.

BACKGROUND: Livedo is a well-known skin condition in patients with systemic lupus erythematosus (SLE) which correspond to small vessels involvement. The influence of antiphospholipid antibodies (aPL) on the occurrence of livedo is controversial. The aim of our study was to estimate the risk of livedo associated with aPL in patients with SLE. METHODS: We conducted a systematic review and meta-analysis of the literature from 1977 to 2021 to estimate the risk of livedo in SLE patients according to different aPL profiles. Data sources were PubMed, Embase, Cochrane Library, hand search, and reference lists of studies. Studies were selected if they included SLE patients with descriptions of the exposure to aPL and the outcome (livedo). Two independent investigators assessed study eligibility, quality, and extracted patient characteristics from each study as well as exposure (aPL) and outcome (livedo). Risk estimates were pooled using random effects models and sensitivity analyses. For all stages of the meta-analysis, we followed the PRISMA guidelines. PROSPERO registration number: CRD42015027377. RESULTS: Of the 2,355 articles identified, 27 were included with a total of 4,810 SLE patients. The frequency of livedo was 25.5% in aPL-positive patients and 13.3% in aPL-negative patients. The overall Odds Ratio (OR) for livedo in aPL-positive patients compared to aPL-negative patients was 2.91 (95% CI; 2.17-3.90). The risk of livedo was significantly increased for most of aPL subtypes, including lupus anticoagulant (LA) (OR = 4.45 [95% CI; 2.21-8.94]), IgG anticardiolipin (OR = 3.95 [95% CI; 2.34-6.65]), and IgG anti-ß2-glycoprotein 1 (OR = 3.49 [95% CI; 1.68-7.27]). CONCLUSIONS: We demonstrated in this meta-analysis an excess risk of livedo in aPL-positive SLE patients compared to aPL-negative patients. For daily practice, in patients with SLE, livedo associated with aPL could correspond to a peculiar group of patients with small vessel disease. Livedo could be a good candidate for inclusion in future classification criteria for antiphospholipid syndrome.

Ophthalmologic manifestations in patients with antiphospholipid antibodies: Beware of iatrogenic complications.

BACKGROUND: Antiphospholipid syndrome (APS) is characterized by several clinical manifestations such as venous and arterial thrombosis associated with persistent antiphospholipid antibodies (aPL). Several studies confirmed that retinal vein occlusion was the most common APS ocular manifestation. The purpose of this study was to identify ophthalmologic manifestations in a homogeneous cohort of well-defined persistently aPL-positive patients and to determine variables associated with these manifestations. METHODS: APL-positive patients were selected from two research programs. All ophthalmologic manifestations including those related to APS were recorded. RESULTS: A total of 117 patients were included and 10 of them had APS-related ophthalmologic manifestations (glaucoma, hydroxychloroquine-related maculopathy, anterior acute uveitis, anterior ischemic optic neuropathy). Systemic Lupus Erythematosus (SLE) (OR = 3.4[95%CI; 0.9-12.7), corticosteroids (OR = 9.0 [95%CI; 2.2-37.7]) and aPL-related nephropathy (OR = 7.1 [95%CI; 1.7-30.0]) were significatively associated with the risk of APS-related ophthalmologic manifestations. CONCLUSION: Most of ocular manifestations in this study were iatrogenic related to corticosteroids or hydroxychloroquine. Patients with SLE, small vessel thrombosis in general, or with aPL-related nephropathy in particular, seemed at higher risk to develop APS-related ophthalmologic manifestations thus deserving adequate monitoring.

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

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

Health-Related Quality of Life in Antiphospholipid Syndrome: Current Knowledge and Future Perspectives.

PURPOSE OF REVIEW: Antiphospholipid syndrome (APS) is a chronic autoimmune disease that can be seen as a burden, with consequences on patients' daily life. Health has traditionally been measured using measures of morbidity or mortality. Health-related quality of life (HRQoL) is a concept that includes quality of life through physical, mental, and social domains. As in other autoimmune diseases, HRQoL has been investigated in patients with APS. Here, we provide a comprehensive review of the current knowledge of the assessment of HRQoL in APS. RECENT FINDINGS: APS patients have an impaired HRQoL compared with the general population. The presence of systemic lupus erythematosus (SLE) in APS patients is associated with a worse HRQoL than in patients without SLE. Several determinants of HRQoL impairment in APS have been identified: age, gender, history of arterial thrombosis, organ damage, lack of social support and treatments. This review highlights the negative impact of thrombosis on APS patients' HRQoL that should not be neglected. Besides, there is a need for a better strategy of communication and information, in order to improve HRQoL in APS.

New Insights into the Use of Direct Oral Anticoagulants in Non-high Risk Thrombotic APS Patients: Literature Review and Subgroup Analysis from a Meta-analysis.

PURPOSE OF REVIEW: The efficacy of direct oral anticoagulants (DOACs) in antiphospholipid syndrome (APS) is discussed. Results from randomized controlled trials are available. It has been stated that a history of arterial thrombosis and triple positivity was associated with a higher risk of thrombosis in APS patients treated with DOACs. However, their efficacy in non-high-risk APS patients with isolated venous manifestations is unsolved. Therefore, we performed a sub-group analysis of a previously published meta-analysis after the exclusion of patients with triple positivity and those with history of arterial or small vessel thrombosis. RECENT FINDINGS: We identified 290 APS patients with previous isolated venous event treated with DOACs; among them, 25 (8.6%) patients experienced a recurrent thrombosis in comparison to 16% in the original cohort. We found that the rate of recurrent thrombosis is lower in APS patients with isolated venous manifestations than in overall APS patients including high-risk patients. Research about DOAC use in non-high-risk APS patients needs to be continued.

Direct Oral Anticoagulants Use in Antiphospholipid Syndrome: Are These Drugs an Effective and Safe Alternative to Warfarin? A Systematic Review of the Literature.

BACKGROUND: The cornerstone of thrombotic antiphospholipid syndrome (APS) patients' management is to prevent recurrent thrombosis by long-term anticoagulation. PURPOSE OF REVIEW: The purpose of the review is to summarize available literature on direct oral anticoagulants (DOACs) use in APS patients through a systematic review and to determine factors associated with thrombosis recurrence. RECENT FINDINGS: The recent RAPS trial demonstrated that APS patients treated with rivaroxaban had a significant twofold-increased thrombin potential, suggesting a higher thrombotic risk, in comparison with warfarin users. Furthermore, several reports of APS patients treated with DOACs have raised safety issues. Our systematic review identified 122 published APS patients treated with DOACs; among them, 19 experienced a recurrent thrombosis while on DOACs. Of note, triple positivity (positivity of all three laboratory criteria for APS) was associated with a 3.5-fold increased risk for recurrent thrombosis. In conclusion, DOACs should be used with caution in APS patients and randomized control trials with clinical primary endpoints assessing clinical efficacy and safety are awaited to establish whether the prescription of DOACs could be a safe alternative to warfarin.

Circulating Endothelial Cells are Associated with Thromboembolic Events in Patients with Antiphospholipid Antibodies.

BACKGROUND: Endothelial damage has been described in antiphospholipid antibody (aPL)-positive patients. However, it is uncertain whether circulating endothelial cells (CECs)-which are released when endothelial injury occurs-can be a marker of patients at high risk for thrombosis. METHODS: Ninety-seven patients with aPL and/or systemic lupus erythematosus (SLE) were included. CECs were determined by an automated CellSearch system. We also assayed plasma levels of tissue factor-bearing extracellular vesicles (TF+/EVs) and soluble triggering receptor expressed on myeloid cells 1 (sTREM-1) as markers of endothelial dysfunction/damage. RESULTS: Patients' mean age was 46.1 ± 13.9 years, 77 were women. Thirty-seven had SLE and 75 patients were suffering from antiphospholipid syndrome. Thirty-seven percent of patients presented a medical history of arterial thrombosis and 46% a history of venous thromboembolism (VTE). Thirteen patients had increased levels of CECs (>20/mL), with a mean CEC level of 48.3 ± 21.3 per mL. In univariate analysis, patients with obesity or medical history of myocardial infarction (MI), VTE, or nephropathy had a significant increased CEC level. In multivariate analysis, obesity (odds ratio [OR] = 6.07, 95% confidence interval [CI]: 1.42-25.94), VTE (OR = 7.59 [95% CI: 1.38-41.66]), and MI (OR = 5.5 [95% CI: 1.1-26.6)] were independently and significantly associated with elevated CECs. We also identified significant correlations between CECs and other markers of endothelial dysfunction: sTREM-1 and TF+/EVs. CONCLUSION: This study demonstrated that endothelial injury assessed by the levels of CECs was associated with thromboembolic events in patients with aPL and/or autoimmune diseases.

Precipitating factors of catastrophic antiphospholipid syndrome: the role of anticoagulant treatment in a series of 112 patients.

BACKGROUND: The prevention of catastrophic antiphospholipid syndrome (CAPS), a rare complication of antiphospholipid syndrome (APS), is a major goal. OBJECTIVES: We analyzed its precipitating factors, focusing on anticoagulation immediately before CAPS episodes. METHODS: We retrospectively analyzed patients in the French multicenter APS/systemic lupus erythematosus database with at least 1 CAPS episode. Then we compared each patient with known APS before CAPS with 2 patients with non-CAPS APS matched for age, sex, center, and APS phenotype. RESULTS: We included 112 patients with CAPS (70% women; mean age, 43 ± 15 years). At least 1 standard precipitating factor of CAPS was observed for 67 patients (64%), which were mainly infections (n = 28, 27%), pregnancy (n = 23, 22%), and surgery (n = 16, 15%). Before the CAPS episode, 67 (60%) patients already had a diagnosis of APS. Of the 61 treated with anticoagulants, 32 (48%) received vitamin K antagonists (VKAs), 23 (34%) heparin, and 2 (3%) a direct oral anticoagulant. They were less likely than their matched patients with APS without CAPS to receive VKA (48% vs 66%, p = .001). Among those treated with VKA, 72% had a subtherapeutic international normalized ratio (ie, <2) versus 28% in patients with APS without CAPS (p < .001). Finally, excluding pregnant patients (n = 14) for whom we could not differentiate the effect of treatment from that of pregnancy, we were left with 47 cases, 32 (68%) of whom had recently begun a direct oral anticoagulant, planned bridging therapy, or had VKA treatment with international normalized ratio <2. CONCLUSION: These results strongly suggest that suboptimal anticoagulation management can trigger CAPS in patients with thrombotic APS.

Cutaneous Involvement in Catastrophic Antiphospholipid Syndrome in a Multicenter Cohort of 65 Patients.

Importance: Catastrophic antiphospholipid syndrome (CAPS) is a severe, rare complication of antiphospholipid syndrome (APS), but cutaneous involvement has not yet been adequately described. Objective: To describe cutaneous involvement during CAPS, its clinical and pathological features, and outcomes. Design, Setting, and Participants: This cohort study was a retrospective analysis of patients included in the French multicenter APS/systemic lupus erythematosus register (ClinicalTrials.gov: NCT02782039) by December 2020. All patients meeting the revised international classification criteria for CAPS were included, and patients with cutaneous manifestations were analyzed more specifically. Main Outcomes and Measures: Clinical and pathological data as well as course and outcome in patients with cutaneous involvement during CAPS were collected and compared with those in the register without cutaneous involvement. Results: Among 120 patients with at least 1 CAPS episode, the 65 (54%) with skin involvement (43 [66%] women; median [range] age, 31 [12-69] years) were analyzed. Catastrophic antiphospholipid syndrome was the first APS manifestation for 21 of 60 (35%) patients with available data. The main lesions were recent-onset or newly worsened livedo racemosa (n = 29, 45%), necrotic and/or ulcerated lesions (n = 27, 42%), subungual splinter hemorrhages (n = 19, 29%), apparent distal inflammatory edema (reddened and warm hands, feet, or face) (n = 15, 23%), and/or vascular purpura (n = 9, 14%). Sixteen biopsies performed during CAPS episodes were reviewed and showed microthrombi of dermal capillaries in 15 patients (94%). These lesions healed without sequelae in slightly more than 90% (58 of 64) of patients. Patients with cutaneous involvement showed a trend toward more frequent histologically proven CAPS (37% vs 24%, P = .16) than those without such involvement, while mortality did not differ significantly between the groups (respectively, 5% vs 9%, P = .47). Conclusions and Relevance: In this cohort study, half the patients with CAPS showed cutaneous involvement, with a wide spectrum of clinical presentations, including distal inflammatory edema. Skin biopsies confirmed the diagnosis in all but 1 biopsied patient.

Intravenous versus subcutaneous tocilizumab in Takayasu arteritis: multicentre retrospective study.

OBJECTIVES: In this large multicentre study, we compared the effectiveness and safety of tocilizumab intravenous versus subcutaneous (SC) in 109 Takayasu arteritis (TAK) patients. METHODS: We conducted a retrospective multicentre study in referral centres from France, Italy, Spain, Armenia, Israel, Japan, Tunisia and Russia regarding biological-targeted therapies in TAK, since January 2017 to September 2019. RESULTS: A total of 109 TAK patients received at least 3 months tocilizumab therapy and were included in this study. Among them, 91 and 18 patients received intravenous and SC tocilizumab, respectively. A complete response (NIH <2 with less than 7.5 mg/day of prednisone) at 6 months was evidenced in 69% of TAK patients, of whom 57 (70%) and 11 (69%) patients were on intravenous and SC tocilizumab, respectively (p=0.95). The factors associated with complete response to tocilizumab at 6 months in multivariate analysis, only age <30 years (OR 2.85, 95% CI 1.14 to 7.12; p=0.027) and time between TAK diagnosis and tocilizumab initiation (OR 1.18, 95% CI 1.02 to 1.36; p=0.034). During the median follow-up of 30.1 months (0.4; 105.8) and 10.8 (0.1; 46.4) (p<0.0001) in patients who received tocilizumab in intravenous and SC forms, respectively, the risk of relapse was significantly higher in TAK patients on SC tocilizumab (HR=2.55, 95% CI 1.08 to 6.02; p=0.033). The overall cumulative incidence of relapse at 12 months in TAK patients was at 13.7% (95% CI 7.6% to 21.5%), with 10.3% (95% CI 4.8% to 18.4%) for those on intravenous tocilizumab vs 30.9% (95% CI 10.5% to 54.2%) for patients receiving SC tocilizumab. Adverse events occurred in 14 (15%) patients on intravenous route and in 2 (11%) on SC tocilizumab. CONCLUSION: In this study, we confirm that tocilizumab is effective in TAK, with complete remission being achieving by 70% of disease-modifying antirheumatic drugs-refractory TAK patients at 6 months.

Antiphospholipid antibodies and the risk of autoimmune hemolytic anemia in patients with systemic lupus erythematosus: A systematic review and meta-analysis.

BACKGROUND: According to criteria for the classification of Systemic Lupus Erythematosus (SLE), autoimmune hemolytic anemia is one of the disease-defining hematologic disorders together with thrombocytopenia. Since the recognition of Antiphospholipid Syndrome (APS), hemolytic anemia was frequently reported but several studies yielded contradictory results on the association between antiphospholipid antibodies (aPL) and hemolytic anemia. Therefore, we evaluated the association of aPL and autoimmune hemolytic anemia in SLE patients by conducting a systematic review and meta-analysis of available literature. METHODS: MEDLINE, EMBASE, Cochrane Library, congress abstracts, and reference lists of eligible studies were searched from 1987 to 2020. Studies were selected if they included SLE patients with descriptions of exposure to aPL and occurrence of hemolytic anemia. Three reviewers extracted study characteristics and association data from published reports. Risk estimates were pooled using random effects models and sensitivity analyses. We followed the PRISMA guidelines for all stages of the meta-analysis (Supplemental Table). PROSPERO registration number: CRD42015027376. RESULTS: From 3555 articles identified, 38 studies met inclusion criteria and included 8286 SLE patients. 20.5% of aPL-positive SLE patients had hemolytic anemia compared to 8.7% in aPL-negative SLE patients. The overall pooled Odds Ratio (OR) for hemolytic anemia in aPL positive patients was 2.83 (95% CI; 2.12-3.79). Among aPL subtypes, the risk of hemolytic anemia was highest for lupus anticoagulant (OR = 3.37 [95% CI; 2.26-5.04]) and, antiß2Glycoprotein I antibodies (OR = 3.21 [95% CI; 1.54-6.72]), especially IgM antiß2Glycoprotein I (OR = 3.01 [95% CI; 1.26, 7.24]). CONCLUSIONS: The occurrence of hemolytic anemia was strongly associated with presence of aPL in SLE patients. Interestingly, IgM isotypes indicate an increased risk of hemolytic anemia in SLE.