Search

Background: Plasma exchange (PEX) treatment for patients with thrombotic thrombocytopenic purpura-hemolytic uremic syndrome (TTP-HUS) has risk for major complications.Study Design and Methods: Data for PEX-related complications have been prospectively collected on all patients enrolled in the Oklahoma TTP-HUS Registry, 1996 to 2011. PEX-related complications have been defined as major or minor and as central venous catheter related or plasma related.Results: During 15 years, 1996 to 2011, 72 (24%) of 302 consecutive patients had major PEX-related complications. Analysis of five consecutive 3-year cohorts demonstrated that there has been a significant trend for decreasing frequency of all PEX-related major complications (p = 0.014) and central venous catheter-related major complications (p = 0.021) but not for the less common plasma-related major complications (p = 0.380). ADAMTS13 activity was measured in 288 (95%) of the 302 patients. Analysis of the 66 patients with ADAMTS13 activity of less than 10% demonstrated a significant trend for decreasing frequency of PEX-related major complications (p = 0.036); the trend for the 222 patients with ADAMTS13 activity of at least 10% was not significant (p = 0.118). The decreased frequency of PEX-related major complications among patients with ADAMTS13 activity of less than 10% may be related to a significant trend for decreasing duration of PEX treatment (p = 0.040) and decreasing frequency of requirement for more than one central venous catheter (p = 0.044). The decreased duration of PEX treatment may be related to increased use of adjunctive treatments: corticosteroids (p < 0.001) and rituximab (p < 0.001).Conclusions: The frequency of PEX-related major complications has decreased from 1996 to 2011, possibly related to increased use of corticosteroids and rituximab and the decreased duration of PEX required to achieve remission. [ABSTRACT FROM AUTHOR]

BACKGROUND: Autopsy studies consistently demonstrate cardiac involvement in thrombotic thrombocytopenic purpura (TTP), but clinical evidence for cardiac abnormalities is rarely reported. STUDY DESIGN AND METHODS: This systematic review addresses the apparent discrepancy between autopsy and clinical data. English language articles were identified by keywords for both TTP and for cardiac symptoms, testing, or events. Patients were analyzed if they were more than 10 years old with idiopathic TTP. RESULTS: Thirty articles were identified that described 111 eligible patients: 20 case reports described 27 patients, 9 retrospective cohort studies described 74 patients, and 1 prospective cohort study described 10 patients. Cardiac events included infarction (26 patients), congestive failure (17), arrhythmias (10), cardiogenic shock (6), and sudden cardiac death (8). Mortality was assessed in 101 patients: 55 died, and 48 autopsies were described. All demonstrated cardiac microvascular thrombi, hemorrhage, and/or necrosis. Follow-up information was reported in only 6 of the 16 patients who survived a cardiac event (follow-up duration, 10 days-2 years; median, 7 weeks). CONCLUSIONS: The frequency and sequelae of clinical cardiac abnormalities in TTP cannot be accurately assessed because most patients were described in reports of few selected patients; many patients were reported before the availability of effective treatment for TTP and sensitive tests for cardiac involvement. Continuing case reports and cohort studies, however, suggest that cardiac abnormalities may be important and often unrecognized causes of mortality and morbidity in patients with TTP. Prospective studies are needed to determine if cardiac therapy can improve survival and long-term outcomes of patients with TTP. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Purpose: To determine the strength of clinical evidence for individual drugs as a cause of thrombocytopenia.Data Sources: All English-language reports on drug-induced thrombocytopenia.Study Selection: Articles describing thrombocytopenia caused by heparin were excluded from review. Of the 581 articles reviewed, 20 were excluded because they contained no patient case reports. The remaining 561 articles reported on 774 patients.Data Extraction: Two of the authors used a priori criteria to independently review each patient case report. Two hundred fifty-nine patient case reports were excluded from further review because of lack of evaluable data, platelet count of 100000 cells/microL or more, use of cytotoxic or nontherapeutic agents, occurrence of drug-induced systemic disease, or occurrence of disease in children. For the remaining 515 patient case reports, a level of evidence for the drug as the cause of thrombocytopenia was assigned. Data on bleeding complications and clinical course were recorded.Data Synthesis: The evidence supported a definite or probable causal role for the drug in 247 patient case reports (48%). Among the 98 drugs described in these reports, quinidine was mentioned in 38 case reports, gold in 11, and trimethoprim-sulfamethoxazole in 10. Of the 247 patients described in the case reports, 23 (9%) had major bleeding and 2 (0.8%) died of bleeding.Conclusions: Many reports of drug-induced thrombocytopenia do not provide evidence supporting a definite or probable causal relation between the disease and the drug. Future patient case reports should incorporate standard criteria to clearly establish the etiologic role of the drug. [ABSTRACT FROM AUTHOR]

Background: Most current treatments for chronic immune thrombocytopenic purpura (ITP) act by decreasing platelet destruction. In a phase 1-2 study, we administered a thrombopoiesis-stimulating protein, AMG 531, to patients with ITP.Methods: In phase 1, 24 patients who had received at least one treatment for ITP were assigned to escalating-dose cohorts of 4 patients each and given two identical doses of AMG 531 (0.2 to 10 microg per kilogram of body weight). In phase 2, 21 patients were randomly assigned to receive six weekly subcutaneous injections of AMG 531 (1, 3, or 6 microg per kilogram) or placebo. The primary objective was to assess the safety of AMG 531; the secondary objective was to evaluate platelet counts during and after treatment.Results: No major adverse events that could be attributed directly to AMG 531 occurred during the treatment period; 4 of 41 patients had transient post-treatment worsening of thrombocytopenia. In phase 1, a platelet count that was within the targeted range (50,000 to 450,000 per cubic millimeter) and at least twice the baseline count was achieved in 4 of 12 patients given 3, 6, or 10 mug of AMG 531 per kilogram. Overall, a platelet count of at least 50,000 per cubic millimeter was achieved in 7 of 12 patients, including 3 with counts exceeding 450,000 per cubic millimeter. Increases in the platelet count were dose-dependent; mean peak counts were 163,000, 309,000, and 746,000 per cubic millimeter with 3, 6, and 10 microg of AMG 531 per kilogram [corrected], respectively. In phase 2, the targeted platelet range was achieved in 10 of 16 patients treated with 1 or 3 mug of AMG 531 per kilogram per week for 6 weeks. Mean peak counts were 135,000, 241,000, and 81,000 per cubic millimeter in the groups that received the 1-mug dose, the 3-mug dose, and placebo, respectively.Conclusions: AMG 531 caused no major adverse events and increased platelet counts in patients with ITP. (ClinicalTrials.gov number, NCT00111475 [ClinicalTrials.gov].). [ABSTRACT FROM AUTHOR]

Abstract: Hereditary thrombotic thrombocytopenic purpura (hTTP) is a rare autosomal recessive, life-threatening disorder caused by a severe deficiency of the plasma enzyme, ADAMTS13. The current estimated prevalence of hTTP in different regions of the world, 0.5 to 2.0 patients per million, is determined by the frequency of diagnosed patients. To evaluate more accurately the worldwide prevalence of hTTP, and also the prevalence within distinct ethnic groups, we used data available in exome and genome sequencing of 807 162 (730 947 exomes, 76 215 genomes) subjects reported recently by the Genome Aggregation Database (gnomAD-v4.1). Among 1 614 324 analyzed alleles in the gnomAD population we identified 6321 distinct ADAMTS13 variants. Of these, 758 were defined as pathogenic; 140 (18%) variants had been previously reported and 618 (82%) were novel (predicted as pathogenic). In total 10 154 alleles (0.6%) were carrying the reported or predicted pathogenic variants; 7759 (77%) with previously reported variants. Considering all 758 pathogenic variants and also only the 140 previously reported variants, we estimated a global hTTP prevalence of 40 and 23 cases per 106, respectively. Considering only the 140 previously reported variants, the highest estimated prevalence was in East Asians (42 per 106). The estimated prevalences of other populations were: Finnish, 32 per 106; non-Finnish Europeans, 28 per 106; Admixed Americans, 19 per 106; Africans/African Americans, 6 per 106; and South Asians, 4 per 106. The lowest prevalences were Middle Eastern, 1 per 106 and Ashkenazi Jews, 0.7 per 106. This population-based genetic epidemiology study reports that hTTP prevalence is substantially higher than the currently estimated prevalence based on diagnosed patients. Many patients with hTTP may not be diagnosed or may have died during the neonatal period., (© 2024 by The American Society of Hematology. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

Intensive care physicians may assume the primary care of patients with transplant-associated thrombotic microangiopathy (TA-TMA), an uncommon but potentially critical complication of hematopoietic stem cell transplants (HSCTs) and solid organ transplants. TA-TMA can have a dramatic presentation with multiple organ dysfunction syndrome (MODS) associated with high morbidity and mortality. The typical presenting clinical features are hemolytic anemia, thrombocytopenia, refractory hypertension, proteinuria and worsening renal failure. Intestinal involvement, with abdominal pain, nausea and vomiting, gastrointestinal bleeding, and ascites are also common. Cardiopulmonary involvement may develop from various causes including pulmonary arteriolar hypertension, pleural and pericardial effusions, and diffuse alveolar hemorrhage. Due to other often concurrent complications after HSCT, early diagnosis and effective management of TA-TMA may be challenging. Close collaboration between ICU and transplant physicians, along with other relevant specialists, is needed to best manage these patients. There are currently no approved therapies for the treatment of TA-TMA. Plasma exchange and rituximab are not recommended unless circulating factor H (CFH) antibodies or thrombotic thrombocytopenic purpura (TTP; ADAMTS activity < 10%) are diagnosed or highly suspected. The role of the complement pathway activation in the pathophysiology of TA-TMA has led to the successful use of targeted complement inhibitors, such as eculizumab. However, the relatively larger studies using eculizumab have been mostly conducted in the pediatric population with limited data on the adult population. This review is focused on the role of intensive care physicians to emphasize the clinical approach to patients with suspected TA-TMA and to discuss diagnosis and treatment strategies., Competing Interests: Declaration of Conflicting InterestsThe authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Abstract: Although it is caused by a single-nucleotide mutation in the β-globin gene, sickle cell anemia (SCA) is a systemic disease with complex, incompletely elucidated pathologies. The mononuclear phagocyte system plays critical roles in SCA pathophysiology. However, how heterogeneous populations of hepatic macrophages contribute to SCA remains unclear. Using a combination of single-cell RNA sequencing and spatial transcriptomics via multiplexed error-robust fluorescence in situ hybridization, we identified distinct macrophage populations with diversified origins and biological functions in SCA mouse liver. We previously found that administering the von Willebrand factor (VWF)-cleaving protease ADAMTS13 alleviated vaso-occlusive episode in mice with SCA. Here, we discovered that the ADAMTS13-cleaved VWF was cleared from the circulation by a Clec4f+Marcohigh macrophage subset in a desialylation-dependent manner in the liver. In addition, sickle erythrocytes were phagocytized predominantly by Clec4f+Marcohigh macrophages. Depletion of macrophages not only abolished the protective effect of ADAMTS13 but exacerbated vaso-occlusive episode in mice with SCA. Furthermore, promoting macrophage-mediated VWF clearance reduced vaso-occlusion in SCA mice. Our study demonstrates that hepatic macrophages are important in the pathogenesis of SCA, and efficient clearance of VWF by hepatic macrophages is critical for the protective effect of ADAMTS13 in SCA mice., (© 2024 American Society of Hematology. Published by Elsevier Inc. All rights are reserved, including those for text and data mining, AI training, and similar technologies.)

Background: Current ADAMTS13 activity assays are important for diagnosing thrombotic thrombocytopenic purpura (TTP) but are unreliable to assay ADAMTS13 activity in animal models. The Cattle-FRETS71 assay is capable of detecting ADAMTS13 activity in plasma from multiple animal species, making it a potentially useful reagent at all stages of clinical research. The performance of Cattle-FRETS71 in TTP diagnosis is not yet known., Objectives: We evaluated the performance of the Cattle-FRETS71 substrate against the human FRETS-rVWF71 and the FRETS-VWF73 commercial substrates in human plasma and serum samples to validate its utility in diagnosing TTP in patients., Methods: Internal validation was performed using heparinized plasma samples (n = 81). External validation was a blinded study using serum samples from the Oklahoma TTP Registry (n = 118, collected 2004-2014) that had been initially assayed by FRETS-VWF73 within 1 year of collection. Additional validation was performed with citrated plasma samples with variable ADAMTS13 activities (n = 32) that were analyzed by FRETS-VWF73., Results: There was an excellent correlation (r = 0.94) between Cattle-FRETS71 and FRETS-rVWF71 for assayed heparinized plasma samples (n = 81). Assay results between Cattle-FRETS71 and FRETS-VWF73 of Oklahoma TTP Registry serum samples (n = 118) and citrated plasma samples (n = 32) were comparably good (r = 0.81 and r = 0.85, respectively)., Conclusion: The Cattle-FRETS71 assay is comparable with other assays in quantifying ADAMTS13 activity in human plasma collected from patients with documented or suspected TTP. The versatility of Cattle-FRETS71, combined with its specificity and sensitivity, makes it a useful tool for the standardization of ADAMTS13 activity across basic and clinical research paradigms., Competing Interests: Declaration of competing interests J.M. holds the patent, “Fluorogenic substrate for ADAMTS13,” US 8663912, issued to Washington University. J.C.B., C.A., F.Z.M., R.K., J.A.K.H., D.T., S.K.V., and J.G. have no conflicts of interest., (Copyright © 2023 International Society on Thrombosis and Haemostasis. Published by Elsevier Inc. All rights reserved.)