Publications by authors named "Katja M J Heitink-Polle"

14 Publications

  • Page 1 of 1

Biological stratification of clinical disease courses in childhood immune thrombocytopenia.

J Thromb Haemost 2021 Apr 18;19(4):1071-1081. Epub 2021 Mar 18.

Department of Immunohematology Diagnostics, Sanquin Diagnostic Services, Amsterdam, The Netherlands.

Background: In childhood immune thrombocytopenia (ITP), an autoimmune bleeding disorder, there is a need for better prediction of individual disease courses and treatment outcomes.

Objective: To predict the response to intravenous immunoglobulins (IVIg) and ITP disease course using genetic and immune markers.

Methods: Children aged younger than 7 years with newly diagnosed ITP (N = 147) from the Treatment With or Without IVIG for Kids with ITP study were included, which randomized children to an IVIg or observation group. A total of 46 variables were available: clinical characteristics, targeted genotyping, lymphocyte immune phenotyping, and platelet autoantibodies.

Results: In the treatment arm, 48/80 children (60%) showed a complete response (platelets ≥100 × 10 /L) that lasted for at least 1 month (complete sustained response [CSR]) and 32 exhibited no or a temporary response (absence of a sustained response [ASR]). For a biological risk score, five variables were selected by regularized logistic regression that predicted ASR vs CSR: (1) hemoglobin; (2) platelet count; (3) genetic polymorphisms of Fc-receptor (FcγR) IIc; (4) the presence of immunoglobulin G (IgG) anti-platelet antibodies; and (5) preceding vaccination. The ASR sensitivity was 0.91 (95% confidence interval, 0.80-1.00) and specificity was 0.67 (95% confidence interval, 0.53-0.80). In the 67 patients of the observation arm, this biological score was also associated with recovery during 1 year of follow-up. The addition of the biological score to a predefined clinical score further improved the discrimination of favorable ITP disease courses.

Conclusions: The prediction of disease courses and IVIg treatment responses in ITP is improved by using both clinical and biological stratification.
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http://dx.doi.org/10.1111/jth.15232DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8048469PMC
April 2021

Hemostatic changes by thrombopoietin-receptor agonists in immune thrombocytopenia patients.

Blood Rev 2020 Nov 10:100774. Epub 2020 Nov 10.

Department of Hematology, Van Creveldkliniek, University Medical Centre Utrecht, Postbox 85500, 3508 GA Utrecht, The Netherlands. Electronic address:

Thrombopoietin receptor agonist (TPO-RA) treatment increases the thrombosis rate in immune thrombocytopenia (ITP). We hypothesize that TPO-RAs influence platelet function, global and secondary hemostasis and/or fibrinolysis. A systematic review was performed. If possible, data were compared between responders (relevant increase in platelet count), and non-responders. Twelve observational studies with 305 patients were included (responders (127/150 (85%))). There were indications that TPO-RA treatment enhanced platelet function, with respect to platelet-monocyte aggregates, soluble P-selectin, GPVI expression, and adhesion under flow. Studies addressing global and secondary hemostasis and fibrinolysis were scarce. Overall, no changes were found during TPO-RA treatment, apart from an accelerated clot formation and conflicting data on levels of plasminogen activator inhibitor (PAI)-1. The parameters that increased have previously been associated with thrombosis in other patient groups, and might contribute to the increased rate of thrombosis observed in TPO-RA-treated ITP patients.
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http://dx.doi.org/10.1016/j.blre.2020.100774DOI Listing
November 2020

A clinical prediction score for transient versus persistent childhood immune thrombocytopenia.

J Thromb Haemost 2021 01 27;19(1):121-130. Epub 2020 Nov 27.

Department of Immunohematology Diagnostics, Sanquin Diagnostic Services, Amsterdam, the Netherlands.

Essentials There is a need for improved tools to predict persistent and chronic immune thrombocytopenia (ITP). We developed and validated a clinical prediction model for recovery from newly diagnosed ITP. The Childhood ITP Recovery Score predicts transient vs. persistent ITP and response to intravenous immunoglobulins. The score may serve as a useful tool for clinicians to individualize patient care. ABSTRACT: Background Childhood immune thrombocytopenia (ITP) is an autoimmune bleeding disorder. The prognosis (transient, persistent, or chronic ITP) remains difficult to predict. The morbidity is most pronounced in children with persistent and chronic ITP. Clinical characteristics are associated with ITP outcomes, but there are no validated multivariate prediction models. Objective Development and external validatation of the Childhood ITP Recovery Score to predict transient versus persistent ITP in children with newly diagnosed ITP. Methods Patients with a diagnosis platelet count ≤ 20 × 10 /L and age below 16 years were included from two prospective multicenter studies (NOPHO ITP study, N = 377 [development cohort]; TIKI trial, N = 194 [external validation]). The primary outcome was transient ITP (complete recovery with platelets ≥100 × 10 /L 3 months after diagnosis) versus persistent ITP. Age, sex, mucosal bleeding, preceding infection/vaccination, insidious onset, and diagnosis platelet count were used as predictors. Results In external validation, the score predicted transient versus persistent ITP at 3 months follow-up with an area under the receiver operating characteristic curve of 0.71. In patients predicted to have a high chance of recovery, we observed 85%, 90%, and 95% recovered 3, 6, and 12 months after the diagnosis. For patients predicted to have a low chance of recovery, this was 32%, 46%, and 71%. The score also predicted cessation of bleeding symptoms and the response to intravenous immunoglobulins (IVIg). Conclusion The Childhood ITP Recovery Score predicts prognosis and may be useful to individualize clinical management. In future research, the additional predictive value of biomarkers can be compared to this score. A risk calculator is available (http://www.itprecoveryscore.org).
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http://dx.doi.org/10.1111/jth.15125DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7839442PMC
January 2021

Anti-platelet antibody immunoassays in childhood immune thrombocytopenia: a systematic review.

Vox Sang 2020 May 20;115(4):323-333. Epub 2020 Feb 20.

Department of Immunohematology Diagnostics, Sanquin Diagnostic Services, Amsterdam, The Netherlands.

Background: In adult immune thrombocytopenia (ITP), an acquired autoimmune bleeding disorder, anti-platelet autoantibody testing may be useful as a rule-in test. Childhood ITP has different disease characteristics, and the diagnostic and prognostic value of anti-platelet antibody testing remains uncertain.

Objective: To systematically review the diagnostic accuracy of anti-platelet autoantibody testing in childhood ITP.

Methods: PubMed and EMBASE were searched for studies evaluating immunoassays in childhood ITP. Study quality was assessed (QUADAS2), and evidence was synthesized descriptively.

Results: In total, 40 studies (1606 patients) were identified. Nine studies reported sufficient data to determine diagnostic accuracy measures. Anti-platelet IgG antibody testing showed a moderate sensitivity (0·36-0·80 platelet-associated IgG [direct test]; 0·19-0·39 circulating IgG [indirect test]). In studies that reported control data, including patients with non-immune thrombocytopenia, specificity was very good (0·80-1·00). Glycoprotein-specific immunoassays showed comparable sensitivity (three studies) and predominantly identified IgG anti-GP IIb/IIIa antibodies, with few IgG anti-GP Ib/IX antibodies. Anti-platelet IgM antibodies were identified in a substantial proportion of children (sensitivity 0·62-0·64 for direct and indirect tests).

Conclusion: The diagnostic evaluation of IgG and IgM anti-platelet antibodies may be useful as a rule-in test for ITP. In children with insufficient platelets for a direct test, indirect tests may be performed instead. A negative test does not rule out the diagnosis of ITP. Future studies should evaluate the value of anti-platelet antibody tests in thrombocytopenic children with suspected ITP.
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http://dx.doi.org/10.1111/vox.12894DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7317748PMC
May 2020

Anti-platelet antibodies in childhood immune thrombocytopenia: Prevalence and prognostic implications.

J Thromb Haemost 2020 05 12;18(5):1210-1220. Epub 2020 Apr 12.

Laboratory for Platelet and Leukocyte Serology, Department of Immunohematology Diagnostics, Sanquin Diagnostic Services, Amsterdam, the Netherlands.

Background: Anti-platelet antibody testing may be useful for the diagnosis and management of childhood immune thrombocytopenia (ITP).

Objectives: Here we aimed to assess the prevalence and prognostic significance of anti-platelet glycoprotein-specific IgM and IgG antibodies.

Methods: Children with newly diagnosed ITP were included at diagnosis and randomized to an intravenous immunoglobulins (IVIg) or careful observation group (TIKI trial). In this well-defined and longitudinally followed cohort (N = 179), anti-platelet glycoprotein-specific IgM and IgG antibodies were determined by monoclonal antibody-immobilization of platelet antigens.

Results: The dominant circulating anti-platelet antibody class in childhood ITP was IgM (62% of patients); but IgG antibodies were also found (10%). Children without IgM platelet antibodies were older and more often female. There was weak evidence for an association between IgM anti-GP IIb/IIIa antibodies and an increased bleeding severity (P = .03). The IgM and IgG anti-platelet responses partially overlapped, and reactivity was frequently directed against multiple glycoproteins. During 1-year follow-up, children with IgM antibodies in the observation group displayed a faster platelet recovery compared to children without, also after adjustment for age and preceding infections (P = 7.1 × 10 ). The small group of patients with detectable IgG anti-platelet antibodies exhibited an almost complete response to IVIg treatment (N = 12; P = .02), suggesting that IVIg was particularly efficacious in these children.

Conclusions: Testing for circulating anti-platelet antibodies may be helpful for the clinical prognostication and the guidance of treatment decisions in newly diagnosed childhood ITP. Our data suggest that the development of even more sensitive tests may further improve the clinical value of antibody testing.
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http://dx.doi.org/10.1111/jth.14762DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7318215PMC
May 2020

Abnormal coagulation parameters are a common non-neuromuscular feature in patients with spinal muscular atrophy.

J Neurol Neurosurg Psychiatry 2020 02 12;91(2):212-214. Epub 2019 Sep 12.

Department of Neurology, UMC Utrecht Brain Center, Utrecht University, Utrecht, The Netherlands

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http://dx.doi.org/10.1136/jnnp-2019-321506DOI Listing
February 2020

Transient and chronic childhood immune thrombocytopenia are distinctly affected by Fc-γ receptor polymorphisms.

Blood Adv 2019 07;3(13):2003-2012

Department of Immunohematology Diagnostics, Sanquin Diagnostic Services, Amsterdam, The Netherlands.

In childhood immune thrombocytopenia (ITP), anti-platelet autoantibodies mediate platelet clearance through Fc-γ receptor (FcγR)-bearing phagocytes. In 75% to 90% of patients, the disease has a transient, self-limiting character. Here we characterized how polymorphisms of FcγR genes affect disease susceptibility, response to intravenous immunoglobulin (IVIg) treatment, and long-term recovery from childhood ITP. Genotyping of the locus was performed in 180 children with newly diagnosed ITP, 22 children with chronic ITP, and 180 healthy control children by multiplex ligation-dependent probe amplification. Children with newly diagnosed ITP were randomly assigned to a single administration of IVIg or observation, and followed for 1 year (Treatment With or Without IVIg for Kids With ITP [TIKI] trial). We defined transient ITP as a complete recovery (≥100 × 10/L) 3 months after diagnosis, including both self-limiting disease/IVIg responders and chronic ITP as absence of a complete recovery at 12 months. ITP susceptibility, as well as spontaneous recovery and response to IVIg, was associated with the genetic variants *ORF and *27W and the promoter variant 2B.4. These variants were overrepresented in patients with transient (N = 131), but not chronic (N = 43), disease. The presence of *ORF predisposed to transient ITP with an odds ratio of 4.7 (95% confidence interval, 1.9-14.3). Chronic ITP was associated with a deletion of (copy number region 1) with an odds ratio of 6.2 (95% confidence interval, 1.8-24.7). Taken together, susceptibility to transient and chronic ITP is distinctly affected by polymorphic variants of genes. Our data suggest that genotyping of the locus may be useful for prognosis and guidance of treatment decisions in newly diagnosed childhood ITP.
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http://dx.doi.org/10.1182/bloodadvances.2019000068DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6616256PMC
July 2019

Intravenous immunoglobulin vs observation in childhood immune thrombocytopenia: a randomized controlled trial.

Blood 2018 08 26;132(9):883-891. Epub 2018 Jun 26.

Department of Pediatric Hematology, University Medical Center Utrecht, Utrecht, The Netherlands.

Management of children with newly diagnosed immune thrombocytopenia (ITP) consists of careful observation or immunomodulatory treatment. Observational studies suggest a lower risk for chronic ITP in children after intravenous immunoglobulin (IVIg) treatment. In this multicenter randomized trial, children aged 3 months to 16 years with newly diagnosed ITP, platelet counts 20 × 10/L or less, and mild to moderate bleeding were randomly assigned to receive either a single infusion of 0.8 g/kg IVIg or careful observation. Primary outcome was development of chronic ITP, which at the time of study initiation was defined as a platelet count lower than 150 × 10/L after 6 months. Two hundred six children were allocated to receive IVIg (n = 102) or careful observation (n = 104). Chronic ITP occurred in 18.6% of the patients in the IVIg group and 28.9% in the observation group (relative risk [RR], 0.64; 95% confidence interval [CI], 0.38-1.08). Platelet counts lower than 100 × 10/L at 12 months (current definition of chronic ITP) were observed in 10% of children in the IVIg group and 12% in the observation group (RR, 0.83; 95% CI, 0.38-1.84). Complete response rates in the first 3 months were significantly higher in the IVIg group. Immunoglobulin G Fc receptor IIb genetic variations were associated with early complete response in both groups. Grade 4 to 5 bleeding occurred in 9% of the patients in the observation group vs 1% in the IVIg group. This trial was registered at www.trialregister.nl as NTR 1563.
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http://dx.doi.org/10.1182/blood-2018-02-830844DOI Listing
August 2018

C-reactive protein enhances IgG-mediated phagocyte responses and thrombocytopenia.

Blood 2015 Mar 29;125(11):1793-802. Epub 2014 Dec 29.

Department of Experimental Immunohematology, Sanquin Research, and Landsteiner Laboratory, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands;

Immune-mediated platelet destruction is most frequently caused by allo- or autoantibodies via Fcγ receptor-dependent phagocytosis. Disease severity can be predicted neither by antibody isotype nor by titer, indicating that other factors play a role. Here we show that the acute phase protein C-reactive protein (CRP), a ligand for Fc receptors on phagocytes, enhances antibody-mediated platelet destruction by human phagocytes in vitro and in vivo in mice. Without antiplatelet antibodies, CRP was found to be inert toward platelets, but it bound to phosphorylcholine exposed after oxidation triggered by antiplatelet antibodies, thereby enhancing platelet phagocytosis. CRP levels were significantly elevated in patients with allo- and autoantibody-mediated thrombocytopenias compared with healthy controls. Within a week, intravenous immunoglobulin treatment in children with newly diagnosed immune thrombocytopenia led to significant decrease of CRP levels, increased platelet numbers, and clinically decreased bleeding severity. Furthermore, the higher the level of CRP at diagnosis, the longer it took before stable platelet counts were reached. These data suggest that CRP amplifies antibody-mediated platelet destruction and may in part explain the aggravation of thrombocytopenia on infections. Hence, targeting CRP could offer new therapeutic opportunities for these patients.
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http://dx.doi.org/10.1182/blood-2014-05-579110DOI Listing
March 2015

Clinical and laboratory predictors of chronic immune thrombocytopenia in children: a systematic review and meta-analysis.

Blood 2014 Nov 10;124(22):3295-307. Epub 2014 Oct 10.

Department of Pediatric Hematology and Oncology, University Medical Center Utrecht/Wilhelmina Children's Hospital, Utrecht, The Netherlands;

Childhood immune thrombocytopenia (ITP) is a rare autoimmune bleeding disorder. Most children recover within 6 to 12 months, but individual course is difficult to predict. We performed a systematic review and meta-analysis to identify predictors of chronic ITP. We found 1399 articles; after critical appraisal, 54 studies were included. The following predictors of chronic ITP in children, assessed in at least 3 studies, have been identified: female gender (odds ratio [OR] 1.17, 95% confidence interval [CI] 1.04-1.31), older age at presentation (age ≥11 years; OR 2.47, 95% CI 1.94-3.15), no preceding infection or vaccination (OR 3.08, 95 CI 2.19-4.32), insidious onset (OR 11.27, 95% CI 6.27-20.27), higher platelet counts at presentation (≥20 × 10(9)/L: OR 2.15, 95% CI 1.63-2.83), presence of antinuclear antibodies (OR 2.87, 95% 1.57-5.24), and treatment with a combination of methylprednisolone and intravenous immunoglobulin (OR 2.67, 95% CI 1.44-4.96). Children with mucosal bleeding at diagnosis or treatment with intravenous immunoglobulin alone developed chronic ITP less often (OR 0.39, 95% CI 0.28-0.54 and OR 0.71, 95% CI 0.52-0.97, respectively). The protective effect of intravenous immunoglobulin is remarkable and needs confirmation in prospective randomized trials as well as future laboratory studies to elucidate the mechanism of this effect.
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http://dx.doi.org/10.1182/blood-2014-04-570127DOI Listing
November 2014

Health-related quality of life in children with newly diagnosed immune thrombocytopenia.

Haematologica 2014 Sep 20;99(9):1525-31. Epub 2014 Jun 20.

Department of Pediatric Hematology and Oncology, University Medical Center/Wilhelmina's Children Hospital, Utrecht, the Netherlands.

Despite its generally transient and benign course, childhood immune thrombocytopenia has a large impact on health-related quality of life. Recently published guidelines state that quality of life should be taken into account while making decisions on management in childhood immune thrombocytopenia. We, therefore, assessed health-related quality of life in children with newly diagnosed immune thrombocytopenia in a prospective multicenter study. One hundred and seven children aged 6 months-16 years (mean age 5.57 years) were included. We used Pediatric Quality of Life Inventory™ and Kids' ITP Tools questionnaires at diagnosis and during standardized follow-up. Scores on the Pediatric Quality of Life Inventory™ Core Scales were compared with those of healthy children. Relationships between health-related quality of life scores and treatment modality, bleeding tendency and course of the disease were examined. Kids' ITP Tools proxy reports and parent self-reports showed significant higher health-related quality of life scores in children who recovered than in children with persistent immune thrombocytopenia (at 3 months: Kids' ITP Tools parent self-report score 80.85 for recovered patients (n=69) versus 58.98 for patients with persistent disease (n=21), P<0.001). No significant differences in health-related quality of life were found between children with mild or moderate bleeding or between children who received intravenous immunoglobulin or children who were carefully observed. In conclusion, health-related quality of life of children with newly diagnosed immune thrombocytopenia is not influenced by treatment modality or bleeding severity, but only by clinical course of the disease. (Dutch Trial Register identifier: NTR TC1563).
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http://dx.doi.org/10.3324/haematol.2014.106963DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4562543PMC
September 2014

High incidence of symptomatic hyperammonemia in children with acute lymphoblastic leukemia receiving pegylated asparaginase.

JIMD Rep 2013 1;7:103-8. Epub 2012 Jul 1.

Department of Pediatric Hematology-Oncology, University Medical Center Utrecht/Wilhelmina Children's Hospital, Room number KC 03.063.0, 85090, 3508 AB, Utrecht, The Netherlands,

Asparaginase is a mainstay of treatment of childhood acute lymphoblastic leukemia. Pegylation of asparaginase extends its biological half-life and has been introduced in the newest treatment protocols aiming to further increase treatment success. Hyperammonemia is a recognized side effect of asparaginase treatment, but little is known about its incidence and clinical relevance. Alerted by a patient with severe hyperammonemia after introduction of the new acute lymphoblastic leukemia protocol, we analyzed blood samples and clinical data of eight consecutive patients receiving pegylated asparaginase (PEG-asparaginase) during their treatment of acute lymphoblastic leukemia. All patients showed hyperammonemia (>50 μmol/L) and seven patients (88 %) showed ammonia concentrations > 100 μmol/L. Maximum ammonia concentrations ranged from 89 to 400 μmol/L. Symptoms varied from mild anorexia and nausea to headache, vomiting, dizziness, and lethargy and led to early interruption of PEG-asparaginase in three patients. No evidence of urea cycle malfunction was found, so overproduction of ammonia through hydrolysis of plasma asparagine and glutamine seems to be the main cause. Interestingly, ammonia concentrations correlated with triglyceride values (r = 0.68, p < 0.0001), suggesting increased overall toxicity.The prolonged half-life of PEG-asparaginase may be responsible for the high incidence of hyperammonemia and warrants future studies to define optimal dosing schedules based on ammonia concentrations and individual asparagine and asparaginase measurements.
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http://dx.doi.org/10.1007/8904_2012_156DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3575055PMC
February 2013

Rapid and full recovery after life-threatening complete atrioventricular block: an isolated feature of myocarditis?

Eur J Pediatr 2004 Jul 28;163(7):410-1. Epub 2004 Apr 28.

Department of Paediatrics, VU Medical Centre, P.O. Box 7057, 1007 MB Amsterdam, The Netherlands.

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http://dx.doi.org/10.1007/s00431-004-1455-4DOI Listing
July 2004