International ITP Registry with Focus on the Asia Pacific Region: Update on Preliminary Findings of Epidemiological and Clinical Data

Background

Immune thrombocytopenia (ITP) is an autoimmune disorder characterized by auto-antibody induced platelet (PLT) destruction and reduced PLT production, leading to a low PLT count (< 100 x 10⁹/L). The availability of robust epidemiological and clinical data outside of Europe and the United States for ITP are limited. There is little uniformity in regards to the treatment of ITP leaving physicians to make treatment decisions based on their experience and institutional protocols. The International ITP Registry is a prospective cohort study which seeks to collect real-world data on the epidemiological and clinical data of adult ITP patients, predominantly from the Asia-Pacific region. The aims of the study are:

1. To compile an anonymous centralised database of demographic, ITP-specific, and co-morbid disease information on ITP patients.

2. To collect data on the presentation and complications of the disease.

3. To document local treatment practices across multiple countries and regions and responses to treatments.

4. To develop and test a prognostic model for major bleeding among adult patients with ITP.

5. To identify factors that predict life-threatening bleeding.

Methods

Recruitment began in 2011. Patients ≥ 18 years old with a recent diagnosis of primary ITP (≤ 6 months since initial diagnosis) are enrolled prospectively upon provision of informed consent. The primary data collected are: patient demographics, laboratory investigations, co-morbidities, bleeding events, blood products used, interventional procedures, pharmacotherapeutic agents administered, response to treatment and adverse events. Data is collected at baseline, at months 6 and 12 and then annually.

Results

At the time of our preliminary update on data from 31 August 2013, 140 patients had been enrolled at 24 sites across 7 countries in the Asia-Pacific Region, Middle East and Latin America. As of 31 August 2016, 517 patients had been enrolled at 44 sites across 10 countries. Gender distribution remains largely unchanged, with fifty eight percent of patients being female (sixty per cent in the preliminary report), the median age of 48 years (range 18 - 96 years) also remains unchanged. Mean PLT count at baseline was 24 x 10⁹/L (range 0 - 94 x 10⁹/L) in 2013, mean PLT count at baseline is now 32 x 10⁹/L (range 0 - 99 x 10⁹/L).

Prior to enrolment fifty five percent of patients had bleeding events recorded in 2013, this rate has now decreased to thirty nine percent.

Corticosteroids remain the most frequently used first-line treatment (59% of patients in 2013 v 76% of patients in 2016). PLT response partial (PR; ≥ 50 x 10⁹/l but ≤ 100 x 10⁹/l & 2 x pre-treatment) or complete (CR; ≥ 100 x 10⁹/l & x 2 pre-treatment) PLT response was 82% in 2013 v 79% at 2016, and cessation of bleeding seen in 100% of these patients in 2013 v 69% in 2016 up to the first 6 month follow-up period. IVIg was also reported as a first line treatment in 14% of patients in 2013, achieving a PLT response in 47% and cessation of bleeding in 82% treated. At the time of this update 26% of all patients had received IVIg with 66% achieving a PLT response and improvement in bleeding in 68% of events. Second line therapies reported in 2013 include splenectomy (n = 3; PR = 1, CR = 2), TPO-receptor agonists (n = 2; PR = 1, CR = 1), immunotherapy (n=22, 14 had a PLT response). In 2016 40 splenectomies are recorded with 79% achieving a PLT response, TPO receptor agonists are given to 48 patients, 51% have a PLT response, and immunotherapy (n= 103; CR=52, PR=31).

Summary/Conclusion

Enrolled patients have an ongoing female predominance with median age of 48 years. Bleeding continues to be frequent at diagnosis with symptoms abating with first line treatments. Corticosteroids remain the most frequently used first line treatment. Splenectomy continues to be used however is still uncommon and was performed in only 7% of our cohort. Immunotherapies are still the most often used second line therapy followed by TPO receptor agonists. Data collection and analysis for this study is ongoing.