Extracorporeal treatment of thrombotic microangiopathy: a ten year experience

Plasma Therapies in Thrombotic Syndromes

Background

Plasma therapies are being applied to thombotic syndromes, but there are limited controlled studies.

Objective

To review the evidence and the current practices for plasma therapies in thrombotic syndromes.

Methods

Expert-enhanced evidence-based analysis. Evidence obtained as of Dec 31, 2002 using Pub Med electronic reference library and expert-obtained library for a total of > 3,000 references obtained using the terms plasma therapy or plasma exchange or plasmapheresis or plasmafiltration or sorbents each combined with the words thrombotic syndrome or sepsis or septic shock. The authors screened the abstracts, reviewed the agreed set of papers, and compiled the recommendations.

Results

Plasma therapies, which alter the plasma components in patients, have been applied in thrombotic syndromes worldwide. In these patients, there is a biologic plausibility for plasma therapies since they have molecules that are prothrombotic and/or antifibrinolytic which would put them at risk for microvascular thrombosis and end-organ damage. There are respectively one randomized controlled trial (RCT) in primary thrombotic syndrome, and secondary thrombotic syndrome, which showed an improvement in mortality in applying plasma therapies (plasma exchange by centrifugation). However, there are numerous non-randomized and case series. Plasma exchange is accepted as the standard therapy for primary thrombotic syndrome as in thrombotic thrombocytopenic purpura (TTP). However, no consensus has been reached for plasma exchange in secondary thrombotic syndromes such as in sepsis, hemolytic uremic syndrome (HUS), thrombocytopenia associated multiple organ failure, TTP/HUS, s/p bone marrow or solid organ transplant, HELLP syndrome, immunologic disorders, drug exposure, or pancreatitis.

Conclusions

As we understand more about the pathophysiology of thrombotic syndromes, specific plasma therapies can be applied for the specific need of a particular patient population. There are sufficient preliminary data to recommend a definitive RCT to evaluate the efficacy of the different types of plasma therapies in secondary thrombotic syndromes.

Use of therapeutic plasma exchange in children with thrombocytopenia-associated multiple organ failure in the Turkish thrombocytopenia-associated multiple organ failure network

OBJECTIVE

Thrombocytopenia-associated multiple organ failure can lead to high mortality in critically ill children, possibly related to consequences of thrombotic microangiopathy. Plasma exchange therapy may improve thrombotic microangiopathy. The purpose of this observational cohort study is to describe whether there is an association between use of plasma exchange therapy and outcome in the Turkish thrombocytopenia-associated multiple organ failure network.

SETTING-INTERVENTIONS

We performed a retrospective cohort analysis in patients with thrombocytopenia-associated multiple organ failure at three different PICUs comparing those who received plasma exchange (+) plus standard therapies with those who did not receive plasma exchange (-) and only received standard therapies.

RESULTS

Among 42 of the enrolled patients with thrombocytopenia-associated multiple organ failure, all had a primary or secondary sepsis diagnosis. Fifteen received plasma exchange therapy (PE [+] group) and 27 received standard medical treatment without plasma exchange (PE [-] group). The mean age was 17.69 months (8.24-54.22) in the PE (+) group and 13.46 months (6.47-20.55) in the PE (-) group. Age (p = 0.232), gender (p = 0.206), thrombocyte count (p = 0.09), Organ Failure Index score (p = 0.111), and pediatric logistic organ dysfunction score (p = 0.177) at admission were not statistically different between groups. The overall 28-day mortality was higher in the PE (-) group (70.37%) compared with the PE (+) group (26.67%) (univariate p = 0.006; multivariate controlling for pediatric logistic organ dysfunction, Organ Failure Index, Pediatric Risk of Mortality scores, and neurological failure p = 0.048). Length of stay was increased in the PE (+) group (p = 0.004).

CONCLUSIONS

The positive association found between use of plasma exchange therapy and improved survival supports the potential of this therapy in Turkish children with thrombocytopenia-associated multiple organ failure. The positive, although less so, associated treatment effect observed after controlling for illness severity provides further rationale for performing a randomized controlled trial in the pediatric Turkish thrombocytopenia-associated multiple organ failure network. Sample size calculations call for a 100-patient trial with a pre hoc interim analysis after enrollment of 50 patients with thrombocytopenia-associated multiple organ failure.

Treatment of thrombotic microangiopathies with plasma exchange

Thrombotic microangiopathy (TMA) is a syndrome characterized by thrombocytopenia, microangiopathic hemolytic anemia, neurologic abnormalities, fever and renal dysfunction. This retrospective analysis sought to determine the clinical characteristics and outcome of patients with TMA treated with plasma exchange at the Department of Dialysis, University Hospital Zagreb. From 1982 to July 2005, 17 patients (10 male and 7 female, age ranging from 18 to 74 years) have been diagnosed with TMA. The most common presenting symptom was purpura in 76.5%, followed by neurologic disturbance in 70.5%, renal function abnormality in 41.1%, and fever in 29.4% of patients. Patients were treated with a daily plasma exchange, which was continued until the normalization of platelet count with minimal hemolysis. Plasma exchange treatment was first tapered and later discontinued with careful monitoring of laboratory parameters. Of the 17 patients, 13 achieved complete remission after 5-32 sessions, two had partial response, and two had no response and died of progressive disease. Four patients developed chronic relapsing TMA, and three of them progressed to end-stage renal disease. Survival at 1 year in our series exceeds 88%, but decreased with duration of follow-up. Overall, with the median follow up of 5 years, 6 patients died from consequences of TMA (35.3%); three with chronic TMA, and 2 in the acute phase of progressive disease. A 74-year old male who developed TMA after prostate cancer died from disseminated malignant disease. Our results demonstrate a high incidence of renal function abnormalities in patients with TMA at presentation, but also during long term follow-up. Development of end-stage renal disease was associated with poor prognosis. Further studies, long term follow-up and establishment of international registries are needed to clarify many dilemmas associated with the diagnosis, treatment and outcomes of patients with TMA.

Plasma exchange therapy for thrombotic microangiopathies

Thrombotic microangiopathies (TMAs) are syndromes associated with thrombocytopenia and multiple organ failure. Plasma exchange is a proven therapy for primary TMA such as thrombotic thrombocytopenic purpura (TTP). There is growing evidence that plasma exchange therapy might also facilitate resolution of organ dysfunction and improve outcomes for secondary TMAs such as disseminated intravascular coagulation (DIC) and systemic inflammation-induced TTP. In this review, we survey the current available evidence and practice of plasma exchange therapy for TMAs.

Pathogenesis of thrombotic microangiopathies

Profound thrombocytopenia and microangiopathic hemolytic anemia characterize thrombotic microangiopathy, which includes two major disorders: thrombotic thrombocytopenic purpura (TTP) and hemolytic uremic syndrome (HUS). TTP has at least three types: congenital or familial, idiopathic, and nonidiopathic. The congenital and idiopathic TTP syndromes are caused primarily by deficiency of ADAMTS13, owing to mutations in the ADAMTS13 gene or autoantibodies that inhibit ADAMTS13 activity. HUS is similar to TTP, but is associated with acute renal failure. Diarrhea-associated HUS accounts for more than 90% of cases and is usually caused by infection with Shiga-toxin-producing Escherichia coli (O157:H7). Diarrhea-negative HUS is associated with complement dysregulation in up to 50% of cases, caused by mutations in complement factor H, membrane cofactor protein, factor I or factor B, or by autoantibodies against factor H. The incomplete penetrance of mutations in either ADAMTS13 or complement regulatory genes suggests that precipitating events or triggers may be required to cause thrombotic microangiopathy in many patients.

Chronic kidney disease in long-term survivors of hematopoietic cell transplantation: epidemiology, pathogenesis, and treatment

High-dose myeloablative hematopoietic cell transplantation is becoming an increasingly common treatment modality for a variety of diseases. Patient survival may be limited by substantial treatment-related toxicities, including chronic kidney disease (CKD). Although the majority of CKD after transplantation is idiopathic, thrombotic microangiopathic syndromes and nephrotic syndrome have been described. Epidemiology, pathogenesis, and potential treatment options for the various clinical syndromes that are associated with CKD in hematopoietic cell transplantation patients is reviewed. As the indications for and the numbers of transplants that are performed worldwide increases, so will the burden of CKD. The nephrologists and oncologists will have to work together to identify patients who are at risk for CKD early to prevent its development and progression to end-stage kidney disease.

Removal of Pathogenic Autoantibodies by Immunoadsorption

Autoimmune diseases result from disrupted tolerance to self-antigens and subsequent damage to tissues and organs. In several diseases, specific autoantibodies have been either proved or suspected to play a role in this process. Consequently, several strategies have been devised in an attempt to discard the destructive immunoglobulins. Currently, both nonselective and epitope-specific methods are applied in several diseases. In this review, we provide a summary of the available data on elimination of pathogenic autoantibodies and discuss the advantages and pitfalls of the different approaches.

Pregnancy outcomes after recovery from thrombotic thrombocytopenic purpura-hemolytic uremic syndrome

BACKGROUND

Recurrent thrombotic thrombocytopenic purpura-hemolytic uremic syndrome (TTP-HUS) during a subsequent pregnancy is an important concern because pregnancy may increase the risk for relapse.

STUDY DESIGN AND METHODS

Outcomes of all pregnancies after recovery from TTP-HUS in the Oklahoma TTP-HUS Registry, a cohort of 301 consecutive patients during the period of 1989 through 2003, were assessed and compared to the total published experience.

RESULTS

In the Oklahoma Registry, 3 of 7 (43%) women with idiopathic TTP-HUS, 2 of 11 (18%) women who were pregnant/postpartum, and 0 of 1 (0%) woman with a bloody diarrhea prodrome at their initial presentation were diagnosed with TTP-HUS during a subsequent pregnancy; all 5 women recovered. In published reports, 10 of 11 (91%) women with idiopathic TTP-HUS and 11 of 18 (61%) women who were pregnant/postpartum at their initial presentation, and all 11 (100%) women with congenital TTP-HUS were diagnosed with TTP-HUS during a subsequent pregnancy. Rates of recurrence in the Oklahoma Registry may be less because of case report bias for exceptional patients. Recurrent TTP-HUS was difficult to diagnose because other pregnancy-related complications were frequent.

CONCLUSIONS

Although pregnancies in these women were often complicated, a future pregnancy may be a safe and appropriate decision for women who have recovered from TTP-HUS.

Therapeutic plasma exchange in patients with grade 2-3 hematopoietic stem cell transplantation-associated thrombotic thrombocytopenic purpura: a ten-year experience

In the present retrospective study we report our 10-year experience with therapeutic plasma exchange (TPE) in 18 patients with grade 2-3 hematopoietic stem cell transplantation (HSCT)-associated thrombotic thrombocytopenic purpura (TTP). During TPE a mean total quantity of 26.5 +/- 15.1 L of plasma was exchanged. Five patients (27.7%) had a complete response eight patients (44.4%) had a partial response while five patients (27.7%) died during TPE treatment. Among the survivors, relapse of TTP occured in three patients (23%) and although these patients were treated again with TPE, all died. First-year survival rate was 41.2%. Our results indicate that TPE may be effective in the treatment of some patients with grade 2-3 HSCT-associated TTP.

Plasmapheresis in thrombotic microangiopathy-associated syndromes: review of outcome data derived from clinical trials and open studies

Current reimbursement policy of health insurance for therapeutic plasmapheresis requires proof of efficacy using the concept of evidence-based medicine. The aim of this paper is to review the outcome of plasmapheresis used to treat thrombotic microangiopathy (TMA)-associated syndromes in the last decade to provide scientific evidence to back up reimbursement applications. The strength of evidence of each reviewed study was assessed using the five levels of evidence criteria as defined by the American Society of Hematology in 1996 for assessment of the treatment of immune thrombocytopenia. The level Experimental indication was added for situations where only case reports or small series supported by pathophysiological reasoning are available. The definitions of evidence used in this paper are as follows: Level I, randomized clinical trial with low rates of error (p < 0.01); Level II, randomized clinical trial with high rates of error (p < 0.05); Level III, nonrandomized studies with concurrent control group; Level IV, nonrandomized studies with historical control group; Level V, case series without a control group or expert opinion; and Experimental, case reports and pathophysiological reasoning. The results of this analysis based on the published data is summarized as follows: The indication of plasmapheresis is assigned to Level IV evidence for thrombotic thrombocytopenic purpura/hemolytic uremic syndrome (TTP/HUS); cancer/chemotherapy-associated TTP/HUS is assigned to Level V evidence; and TTP/HUS refractory to standard plasma exchange and post-bone marrow transplantation TTP/HUS are assigned to Experimental indication. For both subsets, protein A immunoadsorption is reportedly successful. The other TMA-associated syndromes, hemolysis elevated liver enzymes low platelets and HUS in early childhood, are no indication of plasmapheresis. Two randomized clinical trials were performed in order to demonstrate the superiority of plasma exchange/fresh frozen plasma (PEX/FFP) over plasma transfusion in the management of TTP/HUS. The results prove the greater clinical success of the latter type of plasma administration. Standard PEX/FFP has reduced the mortality of TTP/HUS from 94.5% to 13%.

Background and indications for protein A-based extracorporeal immunoadsorption

Protein A (SPA), a major cell wall component of Staphylococcus aureus, has occupied numerous investigators from its discovery in the late fifties. Its availability and avid binding to human immunoglobulins have led to extensive usage for diagnostic and research purposes. Today, SPA-based extracorporeal immunoadsorption relies on two rather different systems, namely, SPA-silica (Prosorba), and SPA-Sepharose (Immunosorba). Both systems are approved by the Food and Drug Administration for the core indications of rheumatoid arthritis and idiopathic thrombocytopenic purpura (SPA-silica) or hemophilia with inhibitors (SPA-Sepharose). Off label indications include immune disorders with a conceivable connection between autoantibody titers and disease activity, like forms of glomerulonephritis, systemic lupus erythematodes, myasthenia, and the Guillain-Barré syndrome as well as alloantibody formation in the context of e.g., transplantation. This review summarizes historical developments and important properties of SPA. Indications for extracorporeal therapy are discussed on the basis of available information and personal experience.

Apheresis for Renal Disease

Many primary renal diseases are associated with either antibody deposition within the glomerulus or an antibody associated autoimmunity, as may be seen with certain vasculitidies. Examples of these diseases include Goodpasture's syndrome, cryoglobulinemia, antineutrophil cytoplasmic antibody positive syndromes, and other forms of rapidly progressive glomerulonephritis. Immunoglobulins also may be nephrotoxic to the tubules such as is the case with myeloma related light chains. Given the rapid removal of immunoglobulins by therapeutic plasma exchange, this modality has been considered an appealing management option in the treatment of these renal diseases. Although not classically considered as autoimmune diseases, thrombotic thrombocytopenic purpura and hemolytic uremic syndrome are related syndromes which often involve the kidneys. Although previously unexplained, it has been long appreciated that therapeutic plasma exchange (PE) can be a useful treatment for these microangiopathic hemolytic anemias, but the most recent insights into their pathogenesis suggest that PE may be beneficial by replacing a missing enzyme or removing pathogenic autoantibodies.