Primary Immune Thrombocytopenia In Children Research Articles

Efficacy and safety of recombinant human thrombopoietin for the treatment of chronic primary immune thrombocytopenia in children and adolescents: A multicentre, randomized, double-blind, placebo-controlled phase III trial.

The efficacy and safety of recombinant human thrombopoietin (rhTPO) in children and adolescent patients with chronic primary immune thrombocytopenia (ITP) remains unclear. A multicentre, randomized, double-blind, placebo-controlled phase III trial was performed. Patients aged 6-17 years, diagnosed with ITP and resistant or relapsed to corticosteroid treatment were included. For the trial, part 1 was exploratory and part 2 was the main analysis, with part 1 determining whether part 2 was stratified by age. Patients in part 1 were treated with rhTPO (the 6- to 11-/12- to 17-year-old groups; 1:1). Patients in part 2 were randomized (3:1) to receive either rhTPO treatment or placebo. Patients received rhTPO or placebo at a dose of 300 U/kg once daily for up to 14 days. A total of 68 patients were included [part 1 (12 patients), part 2 (56 patients)]. The total response rate (TRR) in part 1 was 50.0% (95% CI: 21.09%-78.91%). For part 2, the TRR was 58.5% (95% CI: 42.11%-73.68%) and 13.3% (95% CI: 1.66%-40.46%) in the rhTPO and placebo groups (FAS) respectively. The difference in TRR between the rhTPO group and placebo group was 45.2% (95% CI: 22.33%-68.08%) and 44.6% (95% CI: 21.27%-67.85%) on the FAS and per-protocol set (PPS), respectively, which indicates the superiority of rhTPO treatment.

Study on diagnostic-sensitive markers of primary immune thrombocytopenia in children based on plasma proteomics.

To use proteomic techniques to identify sensitive diagnostic biomarkers for paediatric immune thrombocytopenia (ITP). We selected children in ITP and control groups, using a four-dimensional data-independent acquisition approach (4D-DIA) to analyse its protein expression. The significantly differentially expressed proteins were selected for enzyme-linked immunosorbent assay (ELISA) validation in a cohort comprising 50 samples (13 healthy controls, 15 secondary thrombocytopenia controls and 22 children with ITP). Receiver operating characteristics (ROC) were generated to diagnose ITP and to assess the diagnostic effectiveness of this approach. Compared with the control group, 55 differentially expressed proteins (43 increased and 12 decreased) were determined in the ITP group. Matrix metalloproteinases-9 (MMP-9) and thrombospondin-1 (THBS1) were significantly expressed and selected for ELISA. The verification outcomes aligned with the findings from the proteomic examinations. In contrast to the control cohort, the ITP subjects exhibited markedly elevated plasma MMP-9 levels and reduced plasma THBS1 concentrations. Additionally, the ROC curves indicated the diagnostic value of these biomarkers. In conclusion, proteomics facilitates identifying the sensitive biomarkers for ITP diagnosis. We have preliminarily selected two differentially expressed proteins, MMP-9 and THBS1, whose potential role as biomarkers for diagnosing ITP requires further research.

Comparison of the efficacy and safety of 2 low-dose rituximab regimens in the second-line treatment of primary immune thrombocytopenia in children

Objective: To compare the efficacy and safety of 2 low-dose rituximab regimens in the treatment of children with primary immune thrombocytopenia (ITP). Methods: A total of 90 ITP children admitted to the Hematology Oncology Center of Beijing Children's Hospital from January 2018 to March 2021 were enrolled in this prospective cohort study. In the single-dose group, rituximab was given with a single dose of 375 mg/m2 (maximum dose 600 mg). In the 4-dose group, rituximab was given with a dose of 100 mg weekly (if body weight of the patient ≥ 30 kg, increase dosage to 200 mg weekly) for 4 weeks. Wilcoxon Mann-Whitney test, Chi-square test and Fisher's exact test were used to analyze the difference in efficacy, safety and treatment burden between two groups. Results: Among the 90 children, 41 were male and 49 were female, and the age of medication was 6.8 (4.1,10.0) years. There were 27 cases in the single-dose group and 63 cases in the 4-dose group.There were no significant differences in overall response rate, complete response rate and partial response rate between the single-dose group and 4-dose group (41% (11/27) vs. 33% (21/63), 26% (7/27) vs. 19% (12/63), 15% (4/27) vs. 14%(9/63), χ2=0.45, 0.54, 0.00, all P>0.05). The single-dose group was earlier to get overall response than the 4-dose group (1 (1, 1) vs. 3 (2, 6) weeks, Z=-3.24, P=0.001). There were no significant differences in the sustained response rate, the overall response rate in 1 year, the complete response rate in 1 year, and the partial response rate in 1 year between the single-dose group and the 4-dose group (33% (9/27) vs. 30% (19/63), 30% (8/27) vs. 24% (15/63), 19% (5/27) vs. 14% (9/63), 11% (3/27) vs. 10% (6/63), χ2=0.09, 0.34, 0.04, 0.00, all P>0.05). There were no significant differences in the duration of overall response, recurrence rate within half a year and one year, recurrence time and rate of adverse events between the single-dose group and 4-dose group (all P>0.05). The number of hospitalizations, the duration of hospital stays and the dosage of the single-dose group were significantly lower than those of the 4-dose group (1 (1, 1) vs. 4 (4, 4) times, 5 (4, 7) vs. 8 (5, 8) d, 400 (250, 500) vs. 400 (400, 800) mg, Z=-8.67, -3.03, -4.05, all P<0.05). Conclusions: The single-dose rituximab regimen is comparable to 4-dose rituximab regimen in effectiveness and safety for treatment of children ITP, but more economical and convenient. The single-dose rituximab regimen is more suitable for the second-line treatment of children ITP.

To standardize the diagnosis and treatment of primary immune thrombocytopenia in children

To standardize the diagnosis and treatment of primary immune thrombocytopenia in children

Newly Diagnosed Primary Immune Thrombocytopenia in Children: Which Guideline to Adhere?

Background: Immune thrombocytopenia purpura (ITP) is an autoimmune disorder of bleeding which is defined as having thrombocytopenia (platelet count below 100.000/µL). Most ITP cases in children are acute and recent various guidelines have established a wait-and-see protocol as management for children with ITP since it is assumed to be temporary and will most likely to resolve spontaneously. Objectives: For this case report, a case of primary ITP in a child will be discussed. In the following discussion section, several ITP consensus guidelines will be discerned and compared to see which is the more appropriate guideline to adhere in managing a newly diagnosed ITP case in children. The case report is used as a ‘trigger’ to dissect the core treatment suggestions described in the inspected consensus guidelines. Case Illustration: A 6-years-old female child presents to a hospital with a chief complaint of having red spots in her arms and legs since a day ago. The red spots she complained was the first time to be experienced. She had no prior fever, (bloody) diarrhea, nausea, and vomiting. Physical examination showed no remarkable abnormalities other than numerous petechiae in the upper and lower extremities. Discussion: The patient in this case was finally admitted and treated in the hospital as an inpatient with corticosteroid, antibiotics, and platelet concentrates despite the current guidelines that generally advocate against these treatments. This case report may give an insight regarding the factors needed to be considered before treating a child with newly diagnosed ITP. Conclusion: The Joint Working Group (JWG) consensus seems to be the most comprehensive guideline in treatment of newly diagnosed ITP in children, compared to the American Society of Hematology (ASH) and International Consensus Report guideline. Keywords: hematology, ITP, newly diagnosed, primary, thrombocytopenia Latar Belakang: Immune trombositopenia purpura (ITP) merupakan sebuah penyakit perdarahan otoimun yang didefinisikan sebagai adanya trombositopenia (trombosit dibawah 100.000/µL). Mayoritas kasus ITP pada anak bersifat akut dan konsensus terkini menyarankan protokol “wait and see” sebagai tatalaksana untuk anak dengan ITP karena dianggap hanya sementara dan cenderung akan membaik secara spontan. Tujuan: Untuk laporan kasus ini, sebuah kasus ITP primer pada anak akan dibahas. Pada bagian diskusi, beberapa panduan terkait ITP akan diulas dan diperbandingkan untuk melihat panduan mana yang paling sesuai untuk mengatasi kasus baru (newly diagnosed) ITP pada anak. Laporan kasus ini digunakan sebagai pengantar untuk membahas intisari tatalaksana ITP dalam konsensus-konsensus yang dipakai. Ilustrasi Kasus: Anak perempuan berusia 6 tahun datang ke rumah sakit dengan keluhan utama adanya bintik-bintik merah pada kedua lengan dan tungkainya sejak sehari lalu. Bintik-bintik merah tersebut baru pertama kali dialami. Dia tidak menderita demam, diare (berdarah), nausea, dan vomitus. Pada pemeriksaan fisik, hanya ditemukan petekie-petekie di kedua ekstremitas atas dan bawah. Pembahasan: Pasien dalam kasus ini dirawatinapkan dan diberi kortikosteroid, antibiotik, dan konsentrat trombosit sebagai tatalaksananya, meskipun panduan-panduan yang ada secara umum tidak menyarankan tatalaksana demikian. Laporan kasus ini diharapkan memberikan wawasan terkait faktor-faktor yang penting untuk dipertimbangkan sebelum merawat seorang anak dengan kasus baru ITP. Kesimpulan: Konsensus Joint Working Group (JWG) tampaknya menjadi panduan paling komprehensif dalam tatalaksana anak dengan kasus baru ITP, dibanding panduan American Society of Hematology (ASH) dan International Consensus Report. Kata Kunci: hematologi, ITP, newly diagnosed, primer, trombositopenia

Primary immune thrombocytopenia in children

Primary immune thrombocytopenia in children

Protocol for the study and treatment of primary immune thrombocytopenia: PTI-2018

Primary immune thrombocytopenia, formerly known as immune thrombocytopenic purpura, is a disease for which the clinical and therapeutic management has always been controversial. The ITP working group of the Spanish Society of Paediatric Haematology and Oncology has updated its guidelines for diagnosis and treatment of primary immune thrombocytopenia in children, based on current guidelines, bibliographic review, clinical assays, and member consensus. The main objective is to reduce clinical variability in diagnostic and therapeutic procedures, in order to obtain best clinical results with minimal adverse events and good quality of life.

Protocol for the study and treatment of primary immune thrombocytopenia: ITP-2018

Primary immune thrombocytopenia, formerly known as immune thrombocytopenic purpura, is a disease for which the clinical and therapeutic management has always been controversial. The ITP working group of the Spanish Society of Paediatric Haematology and Oncology has updated its guidelines for diagnosis and treatment of primary immune thrombocytopenia in children, based on current guidelines, bibliographic review, clinical assays, and member consensus. The main objective is to reduce clinical variability in diagnostic and therapeutic procedures, in order to obtain best clinical results with minimal adverse events and good quality of life.

Prognostic factors in immune thrombocytopenia in children

Objective To explore the prognostic relationship between initial absolute lymphocyte count(ALC) of peripheral blood and primary immune thrombocytopenia (ITP) in children, in order to provide basis for judging the prognosis and treatment of ITP in children. Methods Clinical data of 166 children with primary ITP in children admi-tted at the Affiliated Hospital of Guizhou Medical University from January 2014 to March 2018 were analyzed retrospectively, and they were followed up by clinic and telephone, the prognostic factors (gender, age, ethnicity, inducement, bleeding, initial ALC, platelet count and treatment) were statistically analyzed, and the relationship between ALC of peripheral blood and the prognosis of children with ITP was observed. Results Of 166 children with ITP, 89 cases (53.6%) had remission within 3 months, 18 cases (10.8%) within 3-12 months, 20 cases (12.0%) within 1-4 years, a total of 39 cases (23.5%) were refractory (no remission in 1-10 years), the remission rate within 1 year was 64.5%, the total remission rate was 76.4%.ALC of remission cases was (4.58±2.87)×109/L within 3 months, (4.47±2.04)×109/L within 3-12 months, and (2.86±1.61)×109/L within 1- 4 years.Thirty-nine cases (23.5%) were refractory(no remission in 1-10 years), ALC of them was (2.07±0.98)×109/L, and there were significant differences among different groups (F= 12.06, P 12 months) as state variable and ALC as test variable.The area under curve(AUC) was 0.765(P<0.05), cut-off point was 3.925×109/L, sensitivity was 0.542, and specificity was 0.966. Conclusions Initial ALC can be used as one of the prognosis index of ITP in children, and low ALC is the risk signal for chronic development of ITP in children. Key words: Immune thrombocytopenia; Absolute lymphocyte count; Prognosis

Pierwotna małopłytkowość immunologiczna u dzieci

In this article we present current investigation on primary immune thrombocytopenia in children. There are described pathomorphology, clinical symptoms, diagnosis and treatment. We also present current data from literature about genetic tests and latest data on treating options in children. Primary immune thrombocytopenia (ITP) is one of the most frequent hematological disorders in pediatric population. Although the majority of children have a self-limited and short duration of the disease. However, approximately 20-30% of those patients can develop chronic ITP, which can cause significant complications and higher mortality and reduced quality of life. Especially regarding to long-term immunosupression or surgical interventions, such like splenectomy and restrictions on daily activities to avoid trauma. Over the past decades a lot of informations has been reported about pathogenic features of ITP. Nowdays, we know that it is not only caused by increased platet destruction and decreased platet production, but also complex, multifactorial immune dysregulation, like loss of immune tolerance and generation of platelet autoantibodies. In this article we present current investigation on ITP including clinical symptoms, diagnosis, pathomorphology and latests options on treatment in children. We also present current data about genetic biomarker, such as Vanin-1 (VNN-1) which has been suggested as one of predictors of chronic disease and potentially can offer early prognosis estimation.

Analysis of Children with Secondary ITP an Observational Study of Children of the Parc-ITP Registry of the Intercontinental Cooperative ITP Study Group (ICIS)

Background: Immune thrombocytopenia (ITP) is an autoimmune disorder of variable origin that results in bleeding and decreased platelet count. Primary ITP in children is a diagnosis of exclusion, but following practice guidelines only medical history, clinical examination, complete blood count and blood smear analysis are mandatory for diagnosis. Secondary ITP can be difficult to be diagnosed at initial presentation and is frequently identified during the course of the disease. Little is known about children with secondary ITP after a diagnosis of primary ITP. We are describing such patients within a 2 year observation period.Methods and Materials: Data for this study were extracted from the Pediatric and Adult Registry on Chronic ITP (PARC-ITP), an international multi-center registry designed to collect data prospectively in children and adults with newly diagnosed primary ITP. Children aged 3 months to 16 years with a corrected diagnosis of secondary ITP within 24 months after having been diagnosed with primary ITP were included in this analysis. We excluded 37 patients with an undefined diagnosis of secondary ITP, i.e. all patients without a clear statement of the cause of secondary ITP. A correction of diagnosis was reported at 6, 12 or 24 months of follow-up (FU) investigations. Clinical and laboratory data were analyzed with descriptive statistics.Results: A total of 3581 evaluable children with the initial diagnosis of primary ITP were recorded in the PARC-ITP database between 2004 and 2017. Secondary ITP was reported in 99 patients within 24 months FU, 60 were females (60%) with a mean age of 7.13 years (SD 5.2). Diagnosis of secondary ITP was reported with the first FU dataset (6 months after initial diagnosis) in 66 patients. Infectious and autoimmune diseases were the main causes for secondary ITP reported in 43 and 38 patients, respectively. Mean age of patients with infectious diseases was 4.3 years (SD 4.2) and 10 years (SD 4.5) for those with an autoimmune disorder. Other underlying causes were malignancy (n=6), aplastic anemia (n=7), immunodeficiency (n=4) and drugs (n=1). Mean platelet count at initial diagnosis was 22x109/L (SD 24), and 62 patients had a platelet count of < 20x109/l. Patients with malignancy and aplastic anemia had a higher initial platelet count (37 and 38x109/l respectively), than patients with infection or autoimmune diseases (22 and 18x109/l respectively). At the time point of reported secondary ITP the median platelet count was 171x109/L (SD 124) with 59 patients exhibiting platelet counts > 100x109/L. Patients with autoimmune diseases had a higher rate of persisting ITP (61%), than patients with infectious diseases (19%). Overall initial bleeding frequency (n=82) and bleeding location were similar to children with primary ITP. Wet bleeding defined as mucosal bleeding was initially reported in 36% of patients with no differences in the various subgroups. One patient exhibited an intracranial haemorrhage during the course of secondary ITP. A watch and wait strategy was initially applied in 34 patients (34%).Discussion: The diagnosis of primary ITP appears to be accurate for most of the children reported to the PARC-ITP Registry, however, a minority of them experiences a correction of the diagnosis from primary into secondary ITP. Some differences were found for age, sex and initial platelet count in the subgroups of secondary ITP depending on etiology. The characteristics of patients with secondary ITP due to an infection are very similar to primary ITP, reflecting probably similar pathophysiological mechanisms of the immune system. Bleeding symptoms were very similar in all groups.Conclusion: Little is known about patients with initial primary ITP and revision of the diagnosis. This is the first analysis of children with a critical appraisal of the diagnosis “primary ITP”. DisclosuresKuehne:Amgen: Consultancy, Research Funding; UCB: Consultancy.

Study on the pathogenesis of primary immune thrombocytopenia in children

Immune thrombocytopenia (ITP) is the most common hemorrhagic disease in childhood, and immunological abnormality is the most common cause of this disease.Humoral immune abnormalities are the major cause of ITP, involving platelet, platelet membrane surface glycoproteins associated antibodies, impaired Breg cells and upregulation of platelet Toll like receptors.Cellular immune abnormalities include the imbalance of Th1/Th2 cells results in increased inhibitory cytokines [interleukin (IL)-2, interferon-α, tumor necrosis factor-β], IL-17 and Th17 cells in patients with chronic ITP are higher than those in control group, and Treg decline is also common seen in ITP.Increased expression of apoptosis related genes Bak and Bax are also the cause of chronic ITP.Helicobacter pylori is an important cause of chronic ITP, which can be eased in some cases but not effective in new diagnosed cases.Vaccination can lead to ITP, repeated vaccines are applied usually in 3-6 months after the onset. Key words: Immune thrombocytopenia, primary; Humoral immunity; Child

Initial therapy indications of acute primary immune thrombocytopenia in children

Objective To explore the initial therapy indications of acute immune thrombocytopenia (ITP) in children based on the classification treatment. Methods Three hundred and eighty newly diagnosed ITP cases were enrolled in this study from Jan.1st 2012 to Apr.30th 2013 in Children's Hospital Affiliated to Shanghai Jiaotong University.In total 380 patients, there were 214 male cases (56.31%) and 166 female cases(43.68%). The cases were divided into observation group and therapy group according to the initial platelet count which was ≤ 30×109/L or the bleeding over moderate volume or with active bleeding.Platelet values were observed in the observation group weekly, adrenal cortical hormone and immunoglobulin treatment were adopted in the therapy group, cases were followed up to Aug.30th 2013, 9 months on the average. Results Three hundred and five cases showed overall response (80.26%) and 75 cases showed no response(19.74%). One hundred and seventy-eight cases were divided into observation group (46.84%), in which 133 cases (74.72%) showed complete response or response.Two hundred and two cases were included in therapy group (53.16%), in which 167 cases (82.67%) were with complete response or response.There was no statistical difference between the 2 groups in curative effect (Z=-0.54, P=0.59) .Forty-five cases in observation group were no response and accepted therapy, 35 of them (77.78%) had response.There were equal efficiency in the initial therapy group and the subsequent therapy group (χ2=3.60, P=0.06). There was no difference between the age of onset, sex and season in 2 groups.Cases aged from 1 month to 1 year seemed to have a high incidence because of vaccination, and in the cases aged from 3 to 14 years the onset was related to infection. The children over 3 years old had higher risk factors in self-healing and the curative effect.There was no severe bleeding or adverse effect or dead cases in this study. Conclusions It is feasible to take platelet count ≤30×109/L as the threshold for initial therapy indications. Almost half of the cases could avoid overtreatment and pretherapy observation will not reduce the initial cure effect; no severe internal bleeding was observed in all the cases. Key words: Primary immune thrombocytopenia, acute; Initial therapy; Child

Clinical practice: immune thrombocytopenia in paediatrics

Immune thrombocytopenia (ITP) is a disease affecting both children and adults. It is defined as acquired isolated thrombocytopenia caused by the autoimmune production of anti-platelet antibodies. Childhood ITP most frequently occurs in young children who have been previously well, although a viral respiratory tract infection often precedes thrombocytopenia. A benign and self-limiting course is common, but major bleeding complications such as intracranial haemorrhage may occur. Yet one cannot predict which child will have a prolonged course of thrombocytopenia and who will develop an intracranial haemorrhage. In children without atypical characteristics, only minimal diagnostic investigations are needed, and most paediatric ITP patients do not need platelet-enhancing therapy even though various treatment options are available. A "watch and wait" strategy should be considered in paediatric patients with mild disease. Steroids, intravenous immunoglobulin G or anti-D immunoglobulin are the current first-line therapeutic measures for children at risk for severe bleeding. When life-threatening bleeding occurs, a combination of therapies is needed. In this review, we summarise the current knowledge on primary ITP in children and adolescents.

Pierwotna małopłytkowość immunologiczna u dzieci w świetle współczesnych definicji

BackgroundPrimary immune thrombocytopenia (ITP) is one of the most common hematologic disorders in pediatric population. In 2009 the new unified terminology regarding: definition, clinical classification of the disease and response to treatment was proposed. The main study objective was the comparative analysis of clinical aspects of primary ITP in children regarding the contemporary definitions and historical criteria. MethodsData were collected through medical chart review of subjects identified from hospitalization records (Pediatrics, Hematology and Oncology Department) from the period of 2002–2011. ResultsData of 209 subjects were analyzed. According to recent definitions 206/209 patients (98.6%) could be defined. Using the historical criteria 86.12% were classified as acute and 13.88% as chronic ITP. Newly diagnosed primary immune thrombocytopenia was confirmed in 166/206 cases, persistent ITP in 20/206, and chronic ITP in 20/206 of subjects. Depending on applied criteria we noticed significant differences in acute ITP patient number. Regardless of adjusted definitions, the response rates were higher among treated patients (p<0.0001). Historical criteria allowed to recognize lower response rate in patients treated with intravenous immunoglobulins (p=0.009) or steroids (p=0.033). ConclusionsContemporary definitions allow for more adequate categorization on most of the patients with primary immune thrombocytopenia considering the specific clinical aspects and different natural history of primary ITP in children.

Use of Romiplostim for Primary Immune Thrombocytopenia in Children

Very little has been published on the use of romiplostim to treat primary immune thrombocytopenia (ITP), refractory to previous treatments, in children. The objective of this study was to determine its efficacy and safety in pediatric patients in a university general hospital. Retrospective, longitudinal observational study of pediatric patients on treatment with romiplostim. The principal efficacy variable was platelet count. Safety was evaluated by recording possible adverse reactions to the medication, monitoring the appearance of thrombosis, thrombocytopenia during dose reduction, hemorrhage, and myelodysplastic syndromes. Three patients in the authors’ center have been treated with romiplostim (subcutaneous [SC], initial dose: 1 μg/kg/week) for ITP refractory to various treatments: 1 with newly diagnosed ITP and 2 with chronic ITP. Patients were followed up for 27 to 39 weeks after starting treatment. Responses were achieved in 7 to 28 days, and complete responses were maintained for 37% to 91% of the follow-up period, with median platelet counts between 40 × 103/μL and 215 × 103/μL. The adverse reactions observed during follow-up were headache and asthenia in one patient and mucocutaneous bleeding after dose suspension in another one. With regard to effectiveness, the response in the 3 patients was varied. The drug was considered to be safe, as there were only mild adverse reactions. Although further studies and long-term follow-up are required, these results show that romiplostim could be considered an alternative to immunosuppressive therapies, such as rituximab, or splenectomy in refractory chronic ITP.

Epidemiology of primary immune thrombocytopenia in children and adults in Japan: a population-based study and literature review

The epidemiology of primary immune thrombocytopenia (ITP) is not well-characterized in the general population. Most published studies, which have included relatively small numbers of ITP patients, have been conducted in England or Scandinavian countries. No epidemiologic data from Asian countries have been published. This study describes the epidemiology of ITP in a Japanese population. We analyzed the database registry of the Ministry of Health, Labour, and Welfare of Japan, and extracted newly diagnosed acute and chronic ITP patients with a platelet count of <100 × 10(9)/L. From 2004 to 2007, 7,774 cases of ITP were reported, giving an overall incidence of 2.16/100,000/year. The incidence differed greatly between males and females, being 1.72 and 2.58, respectively. The median age of the total affected population was 56 years old. In male patients, there was a striking preponderance of boys below 4 years and a very high peak among those aged 75-89 years. In female patients, the number of ITP patients appeared to show a trimodal distribution by age, with the first peak representing patients below 4 years, the second peak those aged 20-34 years, and the third peak those aged 50-89 years. In conclusion, the incidence of ITP in Japan is not markedly different from that of European countries studied to date. This population-based study reveals that, contrary to previously published studies, the maximum age-specific incidence is in the eighth decade.