Significance of anticardiolipin antibodies on short and long term allograft survival and function following kidney transplantation

Antiphospholipid Syndrome and Kidney Involvement

BACKGROUND

Antiphospholipid syndrome (APS) is an autoimmune disease characterized by the development of autoantibodies and the impairment of the coagulation system. Knowledge about this syndrome is increasing over time, but kidney involvement, especially APS nephropathy, still represents a challenge for physicians.

SUMMARY

A "two hit" model has been hypothesized to explain APS pathophysiology, and the role played by some factors, such as the complement system, is becoming more and more clear. From a clinical point of view, along with thrombosis in any site and/or obstetric morbidities, that are the hallmarks of APS, a constellation of several other clinical symptoms is related to APS. These symptoms alone are not sufficient to fulfill Sydney criteria for APS and this could potentially lead to omitting some diagnoses. The mainstay of management of APS is antithrombotic therapy, but there are expectations for new drugs that regulate the immune system. APS could affect the kidneys in many ways and among them, APS nephropathy is an intriguing entity that has been overlooked in recent years. Novel studies on APS nephropathy are lacking.

KEY MESSAGES

In this review, we discuss what we currently know about APS and its relationship with the kidney, with an eye toward the future perspectives. Multicenter studies on APS nephropathy are necessary in order to develop targeted therapies.

How to Deal With Kidney Retransplantation-Second, Third, Fourth, and Beyond

Kidney transplantation is the best health option for patients with end-stage kidney disease. Ideally, a kidney transplant would last for the lifetime of each recipient. However, depending on the age of the recipient and details of the kidney transplant, there may be a need for a second, third, fourth, or even more kidney transplants. In this overview, the outcome of multiple kidney transplants for an individual is presented. Key issues include surgical approach and immunologic concerns. Included in the surgical approach is an analysis of transplant nephrectomy, with indications, timing, and immunologic impact. Allograft thrombosis, whether related to donor or recipient factors merits investigation to prevent it from happening again. Other posttransplant events such as rejection, viral illness (polyomavirus hominis type I), recurrent disease (focal segmental glomerulosclerosis), and posttransplant lymphoproliferative disease may lead to the need for retransplantation. The pediatric recipient is especially likely to need a subsequent kidney transplant. Finally, noncompliance/nonadherence can affect both adults and children. Innovative approaches may reduce the need for retransplantation in the future.

Recommendations of the Spanish Rheumatology Society for Primary Antiphospholipid Syndrome. Part II: Obstetric Antiphospholipid Syndrome and Special Situations

OBJECTIVE

The difficulty in diagnosis and the spectrum of clinical manifestations that can determine the choice of treatment for antiphospholipid syndrome (APS) has fostered the development of recommendations by the Spanish Society of Rheumatology (SER), based on the best possible evidence. These recommendations can serve as a reference for rheumatologists and other specialists involved in the management of APS.

METHODS

A panel of 4rheumatologists, a gynaecologist and a haematologist with expertise in APS was created, previously selected by the SER through an open call or based on professional merits. The stages of the work were: identification of the key areas for the document elaboration, analysis and synthesis of the scientific evidence (using the Scottish Intercollegiate Guidelines Network, SIGN levels of evidence) and formulation of recommendations based on this evidence and formal assessment or reasoned judgement techniques (consensus techniques).

RESULTS

Forty-six recommendations were drawn up, addressing 5main areas: diagnosis and evaluation, measurement of primary thromboprophylaxis, treatment for APS or secondary thromboprophylaxis, treatment for obstetric APS and special situations. These recommendations also include the role of novel oral anticoagulants, the problem of recurrences or the key risk factors identified in these subjects. This document reflects the last 25, referring to the areas of: obstetric APS and special situations. The document provides a table of recommendations and treatment algorithms.

CONCLUSIONS

Update of SER recommendations on APS is presented. This document corresponds to part II, related to obstetric SAF and special situations. These recommendations are considered tools for decision-making for clinicians, taking into consideration both the decision of the physician experienced in APS and the patient. A part I has also been prepared, which addresses aspects related to diagnosis, evaluation and treatment.

The Role of Cardiolipin and Mitochondrial Damage in Kidney Transplant

Chronic kidney disease (CKD) is highly incident and prevalent in the world. The death of patients with CKD is primarily due to cardiovascular disease. Renal transplantation (RT) emerges as the best management alternative for patients with CKD. However, the incidence of acute renal graft dysfunction is 11.8% of the related living donor and 17.4% of the cadaveric donor. Anticardiolipin antibodies (ACAs) or antiphospholipid antibodies (APAs) are important risk factors for acute renal graft dysfunction. The determination of ACA or APA to candidates for RT could serve as prognostic markers of early graft failure and would indicate which patients could benefit from anticoagulant therapy. Cardiolipin is a fundamental molecule that plays an important role in the adequate conformation of the mitochondrial cristae and the correct assembly of the mitochondrial respiratory supercomplexes and other proteins essential for proper mitochondrial function. Cardiolipin undergoes a nonrandom oxidation process by having pronounced specificity unrelated to the polyunsaturation pattern of its acyl groups. Accumulation of hydroxyl derivatives and cardiolipin hydroperoxides has been observed in the affected tissues, and recent studies showed that oxidation of cardiolipin is carried out by a cardiolipin-specific peroxidase activity of cardiolipin-bound cytochrome c. Cardiolipin could be responsible for the proapoptotic production of death signals. Cardiolipin modulates the production of energy and participates in inflammation, mitophagy, and cellular apoptosis. The determination of cardiolipin or its antibodies is an attractive therapeutic, diagnostic target in RT and kidney diseases.

Therapeutic apheresis in kidney transplantation: An updated review

Therapeutic apheresis is a cornerstone of therapy for several conditions in transplantation medicine and is available in different technical variants. In the setting of kidney transplantation, immunological barriers such as ABO blood group incompatibility and preformed donor-specific antibodies can complicate the outcome of deceased- or living- donor transplantation. Postoperatively, additional problems such as antibody-mediated rejection and a recurrence of primary focal segmental glomerulosclerosis can limit therapeutic success and decrease graft survival. Therapeutic apheresis techniques find application in these issues by separating and selectively removing exchanging or modifying pathogenic material from the patient by an extracorporeal aphaeresis system. The purpose of this review is to describe the available techniques of therapeutic aphaeresis with their specific advantages and disadvantages and examine the evidence supporting the application of therapeutic aphaeresis as an adjunctive therapeutic option to immunosuppressive agents in protocols before and after kidney transplantation.

Antiphospholipid Syndrome Nephropathy: From Pathogenesis to Treatment

Kidney damage is a well-recognized complication of the antiphospholipid syndrome (APS), either primary or systemic lupus erythematosus (SLE)-associated APS. Kidney involvement in APS involves a variety of manifestations, such as renal artery thrombosis or stenosis, renal vein thrombosis, allograft loss due to thrombosis after kidney transplantation, and injury to the renal microvasculature, also known as APS nephropathy. Biopsy in patients with APS nephropathy includes acute thrombotic microangiopathy lesions and chronic intrarenal vascular lesions such as interlobular fibrous intimal hyperplasia, arterial and arteriolar recanalizing thrombosis, fibrous arterial occlusion, and focal cortical atrophy. The most frequent clinical features are hypertension, microscopic hematuria, proteinuria (ranging from mild to nephritic levels), and renal insufficiency. It is uncertain whether antiphospholipid antibodies or other factors are implicated in the development of APS nephropathy, and whether it is driven mainly by thrombotic or by inflammatory processes. Experimental models and clinical studies of thrombotic microangiopathy lesions implicate activation of the complement cascade, tissue factor, and the mTORC pathway. Currently, the management of APS nephropathy relies on expert opinion, and consensus is lacking. There is limited evidence about the effect of anticoagulants, and their use remains controversial. Treatment approaches in patients with APS nephropathy lesions may include the use of heparin based on its role on complement activation pathway inhibition or the use of intravenous immunoglobulin and/or plasma exchange. Targeted therapies may also be considered based on potential APS nephropathy pathogenetic mechanisms such as B-cell directed therapies, complement inhibition, tissue factor inhibition, mTOR pathway inhibition, or anti-interferon antibodies, but prospective multicenter studies are needed to address their role.

Renal involvement in antiphospholipid syndrome

This is a review of scientific publications on renal involvement in antiphospholipid syndrome (APS), with focus on clinical and histopathological findings and treatment. A search for English-language articles on renal involvement in APS covering the period 1980-2017 was conducted in Medline/PubMed and Scopus databases using the MeSH terms "antiphospholipid syndrome", "antiphospholipid antibodies", "glomerulonephritis" and "thrombotic microangiopathy" (TMA). APS nephropathy is primarily the result of thromboses in renal arteries or veins, intraparenchymatous arteries and glomerular capillaries. On histology, APS nephropathy is characterized by TMA, but chronic vaso-occlusive lesions are also commonly observed (fibrous intimal hyperplasia, focal cortical atrophy, fibrous occlusions of arteries). Anticardiolipin and lupus anticoagulant are the most prevalent antibodies in patients with APS nephropathy. The spectrum of renal manifestations includes renal vein thrombosis, renal artery thrombosis/stenosis, TMA, increased allograft vascular thrombosis and malignant hypertension. Anticoagulation is the standard treatment of thrombotic events. In systemic lupus erythematosus (SLE) patients with antiphospholipid antibodies (aPL), kidney failure due to SLE nephritis (immune-complex disease) should be clearly distinguished from kidney failure due to APS-related TMA. In such cases, renal biopsy is mandatory. SLE nephritis requires immunosuppressive therapy, whereas APS nephropathy is usually treated with anticoagulants. Recently, eculizumab and sirolimus have been proposed as a rescue therapy. Based on our review, APS nephropathy appears to be a distinct clinical condition. TMA is a characteristic histopathological finding in APS and is strongly associated with the presence of aPL. This has important therapeutic implications and allows distinguishing APS nephropathy from lupus nephritis.

Living donor renal transplantation in patients with antiphospholipid syndrome: A case report

INTRODUCTION

Antiphospholipid syndrome (APS), autoantibodies directed against phospholipid-binding proteins are associated with cause vascular thrombosis. Patients with APS requiring renal transplantation are at risk of early graft loss due to arterial or venous thrombosis, or thrombotic microangiopathy (TMA). Here, we report 3 cases of successful renal transplantation in patients with APS.

CLINICAL FINDINGS

A 53-year-old man with end-stage renal disease (ESRD) had experienced bilateral deep venous thrombosis (DVT) in the lower extremities 16 years ago and was administered warfarin. However, he frequently experienced recurrent DVT despite of anticoagulation therapy. Before the surgery, APS was confirmed based on positive results lupus anticoagulant in serological tests. A 40-year-old man with polycystic kidney disease and a history recurrent DVT tested positive for lupus anticoagulant and anticardiolipin antibodies. Lastly, a 42-year-old woman with ESRD was diagnosed with APS 7 years ago. She also developed DVT and tested positive for lupus anticoagulant and anti-B2-glycoprotein 1.

THE ANTICOAGULATION PROTOCOL WAS AS FOLLOWS IN ALL CASES

Warfarin was stopped 5 days before living donor renal transplantation and intravenous heparin therapy was started. During surgery, bolus heparin injections (3000 U) were administered to prevent arterial or venous thrombosis. Heparin was substituted with warfarin on postoperative day 4. The third patient (42/F) developed clinical rejection indicated by increased serum creatinine levels and donor-specific antibodies (DSA) and received steroid pulse therapy, plasmapheresis, and rituximab. This treatment restored graft function to within the normal range. The latest graft function in all patients was maintained at normal levels in the outpatient clinic.

CONCLUSIONS

Living donor renal transplantation may be successful in patients with APS following perioperative anticoagulation therapy. However, because of the high risk of TMA or vascular thrombosis in the early postoperative period, close monitoring for hypercoagulability and continuous anticoagulation is essential for maintaining graft function.

Antiphospholipid syndrome and kidney disease

The antiphospholipid syndrome is a common autoimmune disease caused by pathogenic antiphospholipid antibodies, leading to recurrent thrombosis and/or obstetrical complications. Importantly for nephrologists, antiphospholipid antibodies are associated with various renal manifestations including large renal vessel thrombosis, renal artery stenosis, and a constellation of intrarenal lesions that has been termed antiphospholipid nephropathy. This last condition associates various degrees of acute thrombotic microangiopathy, proliferative and fibrotic lesions of the intrarenal vessels, and ischemic modifications of the renal parenchyma. The course of the disease can range from indolent nephropathy to devastating acute renal failure. The pejorative impact of antiphospholipid antibody-related renal complication is well established in the context of systemic lupus erythematous or after renal transplantation. In contrast, the exact significance of isolated antiphospholipid nephropathy remains uncertain. The evidence to guide management of the renal complications of antiphospholipid syndrome is limited. However, the recent recognition of the heterogeneous molecular mechanisms underlying the progression of intrarenal vascular lesions in antiphospholipid syndrome have opened promising tracks for patient monitoring and targeted therapeutic intervention.

Antiphospholipid syndrome, antiphospholipid antibodies and solid organ transplantation

Antiphospholipid syndrome is considered a high risk factor for any kind of surgery. Considering that all solid organ transplants are critically dependent on the patency of vascular anastomosis, there is much concern about the consequences this pro-thrombotic condition may have on transplantation. Relatively little information is available in the literature assessing the real risk that antiphospholipid syndrome or the presence of antiphospholipid antibodies represent in solid organ transplantation. The aim of this article is to review the literature related to transplantation of solid organs in patients diagnosed with antiphospholipid syndrome or patients with positive antiphospholipid antibodies.

Association of early kidney allograft failure with preformed IgA antibodies to β2-glycoprotein I

In the current immunosuppressive therapy era, vessel thrombosis is the most common cause of early graft loss after renal transplantation. The prevalence of IgA anti-β2-glycoprotein I antibodies (IgA-aB2GPI-ab) in patients on dialysis is elevated (>30%), and these antibodies correlate with mortality and cardiovascular morbidity. To evaluate the effect of IgA-aB2GPI-ab in patients with transplants, we followed all patients transplanted from 2000 to 2002 in the Hospital 12 de Octubre prospectively for 10 years. Presence of IgA-aB2GPI-ab in pretransplant serum was examined retrospectively. Of 269 patients, 89 patients were positive for IgA-aB2GPI-ab (33%; group 1), and the remaining patients were negative (67%; group 2). Graft loss at 6 months post-transplant was significantly higher in group 1 (10 of 89 versus 3 of 180 patients in group 2; P=0.002). The most frequent cause of graft loss was thrombosis of the vessels, which was observed only in group 1 (8 of 10 versus 0 of 3 patients in group 2; P=0.04). Multivariate analysis showed that the presence of IgA-aB2GPI-ab was an independent risk factor for early graft loss (P=0.04) and delayed graft function (P=0.04). There were no significant differences regarding patient survival between the two groups. Graft survival was similar in both groups after 6 months. In conclusion, patients with pretransplant IgA-aB2GPI-ab have a high risk of early graft loss caused by thrombosis and a high risk of delayed graft function. Therefore, pretransplant IgA-aB2GPI-ab may have a detrimental effect on early clinical outcomes after renal transplantation.

Increased negative impact of donor HLA-specific together with non-HLA-specific antibodies on graft outcome

BACKGROUND

De novo donor HLA-specific (dnDSA) and non-HLA antibodies including antiangiotensin type 1 receptor antibodies (AT1R-abs) have been associated with antibody-mediated rejection (AMR) and decreased graft survival as well as cellular-mediated rejection (CMR) and early onset of microvasculopathy in heart transplantation. The aim of our study was to determine the impact of anti-AT1R-ab and anti-donor HLA-specific antibody (DSA) on clinical outcomes.

METHODS

Pretransplant and posttransplant sera from 200 recipients transplanted between May 2007 and August 2011 were tested for DSA (Luminex-based single antigen bead assay) and AT1R-ab (enzyme-linked immunosorbent assay). Two cutoff levels (≥ 17 and ≥ 12 units) were used to define high and intermediate binding of AT1R-ab. Clinical parameters examined were 5-year AMR/CMR (≥ grade 2), coronary artery vasculopathy, and survival.

RESULTS

At 2 years after transplant, freedom from AMR and/or CMR was 95.4% for those with no DSA (n=175), 66.9% for those with dnDSA (n=19), and 25% for those with DSA at transplant (n=6) (P<0.0001). Neither ≥ 17 nor ≥ 12 units of pretransplant levels indicated a significant difference in freedom from AMR and/or CMR. When both dnDSA and AT1R-ab ≥ 17 or ≥ 12 units were considered, freedom from AMR and/or CMR decreased to 50% and 45% (P<0.0001), respectively. Coronary artery vasculopathy and survival were not significantly impacted.

CONCLUSIONS

These results show the increased negative impact of dnDSA and AT1R-ab on freedom from AMR and/or CMR and an increased hazard ratio when both parameters are considered. Both HLA- and non-HLA-specific antibodies seem to impact graft outcome in heart transplantation.

Polyreactive antibodies developing amidst humoral rejection of human kidney grafts bind apoptotic cells and activate complement

Antibody mediated rejection (AMR) is associated with a variety of graft-reactive antibodies following kidney transplant. To characterize these antibodies, we immortalized 107 B cell clones from a patient with AMR. In a previous study, we showed that six clones were reacting to multiple self-antigens as well as to HLA and MICA for two of them, thus displaying a pattern of polyreactivity. We show here that all six polyreactive clones also reacted to apoptotic but not viable cells. More generally we observed a nearly perfect overlap between polyreactivity and reactivity to apoptotic cells. Functionally, polyreactive antibodies can activate complement, resulting in the deposition of C3d and C4d at the surface of target cells. Testing the serum of 88 kidney transplant recipients revealed a significantly higher IgG reactivity to apoptotic cells in AMR patients than in patients with stable graft function. Moreover, total IgG purified from AMR patients had increased complement activating properties compared to IgG from non-AMR patients. Overall, our studies show the development of polyreactive antibodies cross-reactive to apoptotic cells during AMR. Further studies are now warranted to determine their contribution to the detection of C4d in graft biopsies as well as their role in the pathophysiology of AMR.

Expansion of polyreactive B cells cross-reactive to HLA and self in the blood of a patient with kidney graft rejection

Antibody rejection is often accompanied by nondonor HLA specific antibodies (NDSA) and self-reactive antibodies that develop alongside donor-specific antibodies (DSA). To determine the source of these antibodies, we immortalized 107 B-cell clones from a kidney transplant recipient with humoral rejection. Two of these clones reacted to HLA class I or MICA. Both clones were also reactive to self-antigens and a lysate of a kidney cell line, hence revealing a pattern of polyreactivity. Monoclonality was verified by the identification of a single rearranged immunoglobulin heavy chain variable region (VH) sequence for each clone. By tracking their unique CDR3 sequence, we found that one such polyreactive clone was highly expanded in the patient blood, representing ~0.2% of circulating B cells. The VH sequence of this clone showed evidence of somatic mutations that were consistent with its memory phenotype and its expansion. Lastly, the reactivity of the expanded polyreactive B-cell clone was found in the patient serum at time of rejection. In conclusion, we provide here proof of principle at the clonal level that human antibodies can cross-react to HLA and self. Our findings strongly suggest that polyreactive antibodies contribute to DSA, NDSA as well as autoantibodies, in transplant recipients.

Eculizumab in acute recurrence of thrombotic microangiopathy after renal transplantation

Renal thrombotic microangiopathy (TMA) is a severe complication of systemic lupus erythematosus (SLE), which is associated with the presence of antiphospholipid (aPL) antibodies. In its most fulminant form, TMA leads to a rapid and irreversible end-stage renal failure. Eculizumab, an anti-C5 monoclonal antibody, is a novel therapy of choice for patients with paroxysmal nocturnal hemoglobinuria (PNH) and atypical hemolytic uremic syndrome. Here, we report the case of a 27-year-old woman, known for SLE and end-stage renal disease due to fulminant TMA. Both aPL antibodies and antinucleosome antibodies were positive. The patient underwent a living-related kidney transplantation with immediate production of urine. Although serum creatinine was remaining high, a graft biopsy, performed on day 6, demonstrated a TMA recurrence. Despite a treatment with plasma exchange, the situation got worse and dialysis was started. Eculizumab treatment was subsequently administered and renal function improved rapidly. Three months after transplantation, serum creatinine was at 100 μmol/L, without proteinuria. This case illustrates the benefit of eculizumab therapy in a fulminant recurrence of TMA after kidney transplantation, resistant to classical therapy.

Severe vascular lesions and poor functional outcome in kidney transplant recipients with lupus anticoagulant antibodies

The impact of antiphospholipid antibodies (APA) on clinical outcome and graft histology following renal transplantation remains poorly known and controversial. We retrospectively explored the functional and histological significance of APA, primarily lupus anticoagulant (LA), in kidney transplant recipients using a systematic evaluation of 3- and 12-month posttransplant screening biopsies and glomerular filtration rate measurements (mGFR). During the study period, 37 patients had APA (2.7%), primarily LA, and 12 fulfilled antiphospholipid syndrome (APS) diagnostic criteria (0.8%) at the time of transplantation. Early after transplantation, 4 of the 12 APS patients died. Early thrombosis of graft vessels and deep venous thrombosis occurred more frequently in APA+ patients than in controls (27% vs. 7%, p < 0.05 and 35% vs. 14%, p < 0.05, respectively). The survival rate was significantly lower in patients with APS. Strikingly, the hallmark lesions of APS-associated nephropathy (APSN) were found in most of screening graft biopsies in APA+ patients but not in the controls. Accordingly, APA+ patients had a dramatic increase in chronic vascular scores and a faster decline in mGFR at 1 year. In conclusion, renal transplantation may be life-threatening in APS patients, and the presence of LA at the time of transplantation is associated with a high rate of allograft APSN and poor transplantation outcomes.

Chronic humoral rejection of human kidney allografts associates with broad autoantibody responses

BACKGROUND

Chronic humoral rejection (CHR) is a major complication after kidney transplantation. The cause of CHR is currently unknown. Autoantibodies have often been reported in kidney transplant recipients alongside antidonor human leukocyte antigen antibodies. Yet, the lack of comprehensive studies has limited our understanding of this autoimmune component in the pathophysiology of CHR.

METHODS

By using a series of ELISA and immunocytochemistry assays, we assessed the development of autoantibodies in 25 kidney transplant recipients with CHR and 25 patients with stable graft function. We also compared the reactivity of five CHR and five non-CHR patient sera with 8027 recombinant human proteins using protein microarrays.

RESULTS

We observed that a majority of CHR patients, but not non-CHR control patients, had developed antibody responses to one or several autoantigens at the time of rejection. Protein microarray assays revealed a burst of autoimmunity at the time of CHR. Remarkably, microarray analysis showed minimal overlap between profiles, indicating that each CHR patient had developed autoantibodies to a unique set of antigenic targets.

CONCLUSION

The breadth of autoantibody responses, together with the absence of consensual targets, suggests that these antibody responses result from systemic B-cell deregulation.

Multifocal avascular necrosis after liver transplantation: an unusual presentation of the antiphospholipid syndrome

We describe the case of a 31-year-old man who presented with an antiphospholipid syndrome (APS), which manifested as multifocal avascular necrosis (AVN) one year after orthotopic liver transplantation. The patient developed multiple AVN affecting hips, left knee, humerus and tarsal bones just after withdrawal of corticosteroid therapy. Three years later when lupus anticoagulant was detected, he began anticoagulant treatment and no further AVN episodes were observed. It is important to be aware of this clinical manifestation of APS, especially in these cases where it can be easily overlooked because of corticosteroid therapy.

Diagnostic value of C4d in renal biopsies

PURPOSE OF REVIEW

Capillary C4d is now an established marker of antibody-mediated rejection in graft biopsies. The technique is widely used to further define the clinical relevance of humoral alloreactivity in various patient subgroups. These include highly sensitized patients, recipients with late graft failure and also some with 'stable' graft function.

RECENT FINDINGS

The C4d technique compares favourably with other techniques that are explored, for example detection of C3d. Capillary C4d can be associated with any graft pathology, including transplant glomerulopathy. C4d is related to circulating alloantibodies but not autoantibodies, and is probably not derived from local sources. Presensitization and de-novo sensitization are important scenarios of humoral alloreactivity that require refined analysis and treatment.

SUMMARY

Detection of C4d in graft biopsies has emerged as an important tool that could substantiate the clinical significance of antibody-mediated rejections. The comprehensive analysis of humoral alloreactivity in the posttransplantation period is still ongoing and will hopefully result in improved patient care and better long-term graft survival.

Anticoagulation therapy in the antiphospholipid syndrome: recent advances

PURPOSE OF REVIEW

The antiphospholipid syndrome is currently best treated with anticoagulation. This review discusses the recent literature addressing the duration, intensity, and appropriateness of anticoagulation or antiplatelet therapy in various clinical subcategories of this syndrome.

RECENT FINDINGS

Several recent articles reaffirm the benefits of long-term anticoagulation in patients with venous thromboembolism or undergoing renal transplantation and support recommendations for usual International Normalized Ratio targets. Aspirin seems to confer benefits similar to those of anticoagulation in arterial stroke. Appropriate anticoagulation strategies for pregnancy are controversial.

SUMMARY

Anticoagulation will remain the mainstay of treatment for most patients with antiphospholipid syndrome. The optimal therapy for specific subgroups of patients will, however, require further good-quality studies.