A British Society for Haematology Guideline: Diagnosis and management of thrombotic thrombocytopenic purpura and thrombotic microangiopathies

The objective of this guideline is to provide healthcare professionals with clear, up-to-date and practical guidance on the management of thrombotic thrombocytopenic purpura (TTP) and related thrombotic microangiopathies (TMAs), including complement-mediated haemolytic uraemic syndrome (CM HUS); these are defined by thrombocytopenia, microangiopathic haemolytic anaemia (MAHA) and small vessel thrombosis. Within England, all TTP cases should be managed within designated regional centres as per NHSE commissioning for highly specialised services.

IVIg-exposure and thromboembolic event risk: findings from the UK Biobank

BACKGROUND

Arterial and venous thromboembolic events (TEEs) have been associated with intravenous Ig use, but the risk has been poorly quantified. We aimed to calculate the risk of TEEs associated with exposure to intravenous Ig.

METHODS

We included participants from UK Biobank recruited over 3 years, data extracted September 2020.The study endpoints were incidence of myocardial infarction, other acute ischaemic heart disease, stroke, pulmonary embolism and other venous embolism and thrombosis.Predictors included known TEE risk factors: age, sex, hypertension, smoking status, type 2 diabetes mellitus, hypercholesterolaemia, cancer and past history of TEE. Intravenous Ig and six other predictors were added in the sensitivity analysis.Information from participants was collected prospectively, while data from linked resources, including death, cancer, hospital admissions and primary care records were collected retrospectively and prospectively.  FINDINGS: 14 794 of 502 492 individuals had an incident TEE during the study period. The rate of incident events was threefold higher in those with prior history of TEE (8 .7%) than those without previous history of TEE (3.0%).In the prior TEE category, intravenous Ig exposure was independently associated with increased risk of incident TEE (OR=3.69 (95% CI 1.15 to 11.92), p=0.03) on multivariate analysis. The number needed to harm by exposure to intravenous Ig in those with a history of TEE was 5.8 (95% CI 2.3 to 88.3).Intravenous Ig exposure did not increase risk of TEE in those with no previous history of TEE.

INTERPRETATION

Intravenous Ig is associated with increased risk of further TEE in individuals with prior history of an event with one further TEE for every six people exposed. In practice, this will influence how clinicians consent for and manage overall TEE risk on intravenous Ig exposure.

Real-world, single-center experience of SARS-CoV-2 vaccination in immune thrombocytopenia

BACKGROUND

Immune thrombocytopenic purpura (ITP) relapse following vaccination remains poorly reported in the adult population.

OBJECTIVES

This report details real world data from the largest single-center cohort of ITP relapse following severe acute respiratory syndrome (SARS-CoV-2) vaccination.

METHODS

The vaccination status of 294 patients under active follow-up was reviewed. A total of 17 patients were identified resulting in an incidence of ITP relapse following SARS-CoV-2 vaccination in this cohort of 6.6% and an incidence of newly diagnosed ITP following SARS-CoV-2 vaccination of 1.4%.

RESULTS

Patients were noted to develop marked deviation of platelet count from baseline following vaccination (P =< .0001). Fourteen patients had a prior diagnosis of ITP and median follow-up following diagnosis was 4 years (range 0-45 years). Days from vaccination to presentation ranged from 2-42 (median 14) and the follow-up period was 34 weeks. Fifteen patients (88%) presented with symptoms and all 17 patients developed symptoms during the follow-up period. Nine patients (53%) received a second dose of vaccine during the follow-up period with seven patients (78%) requiring therapeutic support to facilitate second vaccination. Decision to treat patients was multi-factorial and aimed at decreasing bleeding symptoms and obtaining a platelet count >30 × 109 /L. Sixteen patients (94%) required therapeutic intervention and at the end of the follow-up period, four patients (24%) remained unresponsive to treatment with a platelet count <30 × 109 /L.

CONCLUSION

Vaccination of ITP patients continues to have important clinical benefit; however, recommendations for patients who relapse remain lacking. This report outlines the real-world patient outcomes in the era of widespread SARS-CoV-2 vaccination.

Pharmacological venous thromboembolism prophylaxis in elective cranial surgery: a systematic review of time of initiation, regimen and duration

INTRODUCTION

Pharmacological prophylaxis of venous thromboembolism (VTE) requires nuanced decision-making to balance the risk of VTE against haemorrhage. This problem is compounded in neurosurgical patients, in whom postoperative intracranial haemorrhage (ICH) may be catastrophic, compared to non-neuraxial bleeding in other types of surgery. Current major guidelines recommend caution when using pharmacological prophylaxis in elective cranial surgery, but incorporate low-quality evidence and lack precise guidance on timing and duration of anticoagulation.

METHODS

We aimed to answer the following questions for patients undergoing elective cranial surgery: (1) when is the optimal time to initiate postoperative anticoagulation, and (2) how long should postoperative anticoagulation be continued for? In this systematic review, we screened randomised and non-randomised studies reporting original data on pharmacological VTE prophylaxis in elective cranial surgery. Outcomes of interest were VTE and ICH.

RESULTS

Three retrospective, single-centre observational studies met eligibility criteria, with a total of 923 participants. Meta-analysis was not performed due to a high risk of bias across all studies. Through narrative synthesis, we found that patients who developed VTE were significantly more likely to receive their first postoperative dose at a later time (mean: 144 vs. 29 h, p = .04). Shorter courses of anticoagulation (<7 days) were associated with significantly lower ICH rates (p = .03) compared to longer courses (>21 days).

CONCLUSION

The limited evidence favours earlier initiation and shorter courses of thromboprophylactic anticoagulation. These findings are specific to patients undergoing surgery for meningioma or glioma and may not apply to other populations. Randomised controlled trials or robustly designed observational studies are necessary to establish a clearer evidence base.

Patient characteristics in tardive COVID-19 pseudoperniosis: a case series of 16 patients

Background

Acute pseudoperniosis (PP) has a recognized association with COVID‐19 and tends to occur without cold precipitation in young, healthy patients, often without a clear history of COVID‐19. These lesions usually resolve within 2 weeks and without long‐term sequelae. In the early months of 2021, patients with delayed and protracted PP began to emerge. We have called this presentation ‘tardive COVID‐19 PP (TCPP)’.

Aim

To consolidate and expand knowledge on TCPP, we describe the clinical characteristics, treatments and outcomes of 16 patients with TCPP who were reviewed by our outpatient dermatology service.

Results

The initial clinical manifestations were erythema, swelling and PP of the fingers in 56.2%, and of the toes in 31.2%, desquamation in 56.2% and acrocyanosis in 12.5%. Ten patients had eventual involvement of all acral sites. The median duration of symptoms was 191 days. Six patients reported close contact with a confirmed or suspected case of COVID‐19, but only two had positive COVID‐19 tests. Four patients experienced complete or almost complete resolution of symptoms, while the rest remain under active treatment.

Conclusion

Unlike acute PP, TCPP has a protracted and delayed presentation that is typically associated with profound acrocyanosis. Patients with TCPP represent a new phenomenon that is part of the post‐COVID‐19 syndrome, with risk factors and pathophysiology that are not yet fully understood. Our data indicate that likely predisposing factors for developing TCPP include young age, a preceding history of cold intolerance and an arachnodactyloid phenotype. Anorexia, connective tissue disorders or sickle cell trait may also predispose to TCPP. In addition, low titre antinuclear antibody positivity, the presence of cryoglobulins, or low complement levels may represent further risk factors. Finally, prolonged low temperatures are also likely to be contributing to the symptoms.

Tapering and Discontinuation of Thrombopoietin Receptor Agonist Therapy in Patients with Immune Thrombocytopenia: Results from a Modified Delphi Panel

BACKGROUND

Recent evidence suggests that in patients with immune thrombocytopenia (ITP) with a stable response on thrombopoietin receptor agonists, treatment may be tapered and/or discontinued.

OBJECTIVES

The objective of this study was to provide a guide for tapering and discontinuation of TPO-RA therapy in patients with ITP, based on hematologist survey results, existing evidence, and expert consensus.

PATIENTS/METHODS

UK hematologists completed a survey to characterize self-reported practice patterns related to TPO-RA tapering and discontinuation in patients with ITP. Using a modified Delphi panel approach, ITP experts developed consensus statements regarding the use of TPO-RA tapering and discontinuation.

RESULTS

Survey respondents estimated that 30-34% of their patients were suitable for tapering or discontinuation and that 29-35% of these patients required treatment re-initiation after an average treatment-free interval of 86-106 days. No clear predictors of patient suitability or response to tapering or discontinuation were identified. The ITP expert consensus was that approximately 30% of patients are eligible for tapering and discontinuation, which may be considered after 6-12 months for patients demonstrating an adequate treatment response (platelet count >50,000/µL at ≥75% of assessments in the preceding 6 months). Treatment re-initiation may be considered if the platelet count decreases or if the patient becomes symptomatic. Individual differences need to be taken into account when considering TPO-RA tapering or discontinuation.

CONCLUSIONS

Tapering and discontinuation of TPO-RA therapy may be considered for certain patients with ITP. Further study is needed to better predict patients likely to achieve sustained off-treatment responses after tapering and discontinuation.

Immune thrombocytopenia in adults: A single-centre review of demographics, clinical features and treatment outcomes

OBJECTIVES

Primary immune thrombocytopenia (ITP) is a bleeding disorder characterised by an isolated thrombocytopenia in the absence of an alternative diagnosis. The condition is highly heterogeneous with some patients requiring multiple of therapy before achieving response. In this study, we collected data on a large cohort of primary ITP patients with the objective of identifying variables which may predict treatment requirements.

METHODS

We collected data on 379 patients, 275 with a confirmed diagnosis of primary ITP included demographics, baseline laboratory results and treatments. These were compared against treatment responses and lines of therapy.

RESULTS

Patients who presented with a platelet count of <30 × 10⁹ /L or bleeding symptoms were observed to require more subsequent lines of therapy (P-value <0.001). 32% of patients (n = 87) received no treatment, and these patients had a significantly higher median count compared to those with required >2 lines of therapy (P-value <0.001). Superior response rates were demonstrated with thrombopoietin receptor agonists when compared with other agents irrespective of baseline characteristics.

CONCLUSIONS

Platelet counts at diagnosis are a potentially strong predictive indicator of subsequent lines of therapy. Patients with bleeding symptoms at diagnosis were more likely to have lower median platelets counts.

Bethesda Assay for Detecting Inhibitory Anti-ADAMTS13 Antibodies in Immune-Mediated Thrombotic Thrombocytopenic Purpura

A diagnosis of thrombotic thrombocytopenic purpura (TTP) is confirmed by a severe deficiency (<10%) of a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13 (ADAMTS13) activity. Autoantibodies to ADAMTS13 can be detected with a simplified enzyme-linked immunosorbent assay (ELISA). An alternative methodology is a Bethesda assay, which has never been formally assessed in TTP. This study aimed to investigate the inhibitory anti-ADAMTS13 antibody assay and determine if the Bethesda assay is advantageous compared with the ELISA, measuring total immunoglobulin G (IgG) antibodies to ADAMTS 13. The Bethesda method determines the neutralizing activity of anti-ADAMTS13 antibodies in pooled normal plasma. We selected six immune-mediated TTP (iTTP) patients with ADAMTS13 activity levels <10% and strong ADAMTS13 inhibitors by 50:50 mixing studies and analyzed anti-ADAMTS13 antibodies using the Bethesda and ELISA assays. ADAMTS13 activity was stable at room temperature, while a time-dependent decrease in activity was detected in assay conditions of 37°C. Adding 5 mM Ca 2+ to citrated plasma prevented loss of ADAMTS13 activity with time. There was time dependence to the antibody-mediated inactivation, after 2-hour incubation. Two of the iTTP patients had no detectable ADAMTS13 antibodies by the Bethesda assay, but had high titer of anti-ADAMTS13 antibodies and low ADAMTS13 antigen levels. The Bethesda assay can only detect anti-ADAMTS13 antibodies that functionally inhibit ADAMTS13. The anti-ADAMTS13 IgG ELISA instead allows the rapid identification of total IgG autoantibodies, detecting both inhibitory and noninhibitory antibodies.

Presenting ADAMTS13 antibody and antigen levels predict prognosis in immune-mediated thrombotic thrombocytopenic purpura

Immune-mediated thrombotic thrombocytopenic purpura (TTP) is a life-threatening disorder caused by antibodies against ADAMTS13. From the United Kingdom TTP registry, we undertook a prospective study investigating the impact of the presenting anti-ADAMTS13 IgG antibody and ADAMTS13 antigen on mortality. A total of 312 episodes involving 292 patients over 87 months were included; 68% were female, median age 46 (range, 11-88 years), and median presenting ADAMTS13 of <5% (range, <5%-18%). The mortality rate was 10.3% (n = 32); 68% of patients had a raised troponin at presentation conferring a sixfold increase in mortality compared with those with normal troponin levels (12.1% vs 2.0%, P = .04). Twenty-four percent had a reduced Glasgow Coma Score (GCS) at presentation with a ninefold increase in mortality (20% vs 2.2% for normal GCS at presentation, P < .0001). Mortality increased with higher anti-ADAMTS13 antibody levels and lower ADAMTS13 antigen levels. Those with antibody levels in the upper quartile (antibody >77%) had a mortality of 16.9% compared with 5.0% for the lowest quartile (antibody <20%) (P = .004). Those with an antigen level in the lowest quartile (antigen <1.5%) had a mortality of 18% compared with 3.8% for the highest quartile (antigen >11%) (P = .005). The synergistic effect of anti-ADAMTS13 IgG antibody in the upper quartile and ADAMTS13 antigen in the lowest quartile had the highest mortality of 27.3%. We conclude that both anti-ADAMTS13 IgG antibody and ADAMTS13 antigen levels correlate with outcome in TTP with increased cardiac and neurological involvement and increased mortality.

A single-center prospective study on the safety of plasma exchange procedures using a double-viral-inactivated and prion-reduced solvent/detergent fresh-frozen plasma as the replacement fluid in the treatment of thrombotic microangiopathy

BACKGROUND

Patients presenting with acute episodes of thrombotic microangiopathies (TMAs) require urgent access to plasma exchange (PEX). OctaplasLG, a solvent/detergent fresh-frozen plasma product that has undergone viral inactivation and prion reduction step, has been used in our institution since 2013, replacing Octaplas.

STUDY DESIGN AND METHODS

We prospectively reviewed 981 PEX procedures where OctaplasLG was the replacement fluid in 90 patients admitted acutely with a TMA presentation within our institution from January 1, 2013, to December 31, 2015. We recorded citrate toxicities, plasma reactions, viral transfer, complications related to central venous catheter, and venous thrombotic events (VTEs).

RESULTS

Citrate toxicities were 5.4%, plasma reactions were 2%, and all were classified as Grade 1 or 2. VTE had an incidence of 12.2%, although 50% of the episodes occurred in early remission when patients were not receiving PEX. No line insertions complications were recorded. Line-associated infections were 2.2%. Hepatitis B and C serology and human immunodeficiency virus (HIV) were checked on admission. There were four patients who may have had passive transient transfer of hepatitis B antibodies from pooled plasma. No hepatitis C or HIV viral transfer was documented after treatment and no seroconversion was detected after treatment.

CONCLUSION

Our data have demonstrated that the incidence of complications during PEX is low and using OctaplasLG is comparable to the low incidence of reactions. No cases of anaphylaxis, transfusion-related acute lung injury, or fatal plasma reactions were seen. There was no evidence of viral transmission or seroconversion after treatment.

The role of complement activation in COPD exacerbation recovery

Complement anaphylatoxins (C3a, C5a) are potent inflammatory mediators, implicated in the exaggerated inflammatory response seen in chronic obstructive pulmonary disease (COPD) [1]. COPD patients have decreased levels of serum C3 and C4 [2, 3], and higher levels of sputum C3a and C5a, than healthy volunteers [4]. Both sputum and serum C5a levels climb during acute exacerbations [1, 5]. Serum C5a during COPD exacerbations has been positively correlated with C-reactive protein (CRP) and negatively correlated with percentage predicted forced expiratory volume in 1 s (FEV₁ % pred) [5].

Rise in sputum complement (C3a, C5a) levels during COPD exacerbation is associated with recovery timehttp://ow.ly/ZaPj303xxPf

Caplacizumab for Acquired Thrombotic Thrombocytopenic Purpura

BACKGROUND

Acquired thrombotic thrombocytopenic purpura (TTP) is caused by aggregation of platelets on ultralarge von Willebrand factor multimers. This microvascular thrombosis causes multiorgan ischemia with potentially life-threatening complications. Daily plasma exchange and immunosuppressive therapies induce remission, but mortality and morbidity due to microthrombosis remain high.

METHODS

Caplacizumab, an anti-von Willebrand factor humanized single-variable-domain immunoglobulin (Nanobody), inhibits the interaction between ultralarge von Willebrand factor multimers and platelets. In this phase 2, controlled study, we randomly assigned patients with acquired TTP to subcutaneous caplacizumab (10 mg daily) or placebo during plasma exchange and for 30 days afterward. The primary end point was the time to a response, defined as confirmed normalization of the platelet count. Major secondary end points included exacerbations and relapses.

RESULTS

Seventy-five patients underwent randomization (36 were assigned to receive caplacizumab, and 39 to receive placebo). The time to a response was significantly reduced with caplacizumab as compared with placebo (39% reduction in median time, P=0.005). Three patients in the caplacizumab group had an exacerbation, as compared with 11 patients in the placebo group. Eight patients in the caplacizumab group had a relapse in the first month after stopping the study drug, of whom 7 had ADAMTS13 activity that remained below 10%, suggesting unresolved autoimmune activity. Bleeding-related adverse events, most of which were mild to moderate in severity, were more common with caplacizumab than with placebo (54% of patients vs. 38%). The frequencies of other adverse events were similar in the two groups. Two patients in the placebo group died, as compared with none in the caplacizumab group.

CONCLUSIONS

Caplacizumab induced a faster resolution of the acute TTP episode than did placebo. The platelet-protective effect of caplacizumab was maintained during the treatment period. Caplacizumab was associated with an increased tendency toward bleeding, as compared with placebo. (Funded by Ablynx; ClinicalTrials.gov number, NCT01151423.).

Complement and cytokine response in acute Thrombotic Thrombocytopenic Purpura

Complement dysregulation is key in the pathogenesis of atypical Haemolytic Uraemic Syndrome (aHUS), but no clear role for complement has been identified in Thrombotic Thrombocytopenic Purpura (TTP). We aimed to assess complement activation and cytokine response in acute antibody-mediated TTP. Complement C3a and C5a and cytokines (interleukin (IL)-2, IL-4, IL-6, IL-10, tumour necrosis factor, interferon-γ and IL-17a) were measured in 20 acute TTP patients and 49 remission cases. Anti-ADAMTS13 immunoglobulin G (IgG) subtypes were measured in acute patients in order to study the association with complement activation. In acute TTP, median C3a and C5a were significantly elevated compared to remission, C3a 63·9 ng/ml vs. 38·2 ng/ml (P < 0·001) and C5a 16·4 ng/ml vs. 9·29 ng/ml (P < 0·001), respectively. Median IL-6 and IL-10 levels were significantly higher in the acute vs. remission groups, IL-6: 8 pg/ml vs. 2 pg/ml (P = 0·003), IL-10: 6 pg/ml vs. 2 pg/ml (P < 0·001). C3a levels correlated with both anti-ADAMTS13 IgG (r_s = 0·604, P = 0·017) and IL-10 (r_s = 0·692, P = 0·006). No anti-ADAMTS13 IgG subtype was associated with higher complement activation, but patients with the highest C3a levels had 3 or 4 IgG subtypes present. These results suggest complement anaphylatoxin levels are higher in acute TTP cases than in remission, and the complement response seen acutely may relate to anti-ADAMTS13 IgG antibody and IL-10 levels.