Association of Platelet Parameters With Bleeding Severity in Children With ITP

Many children with severe immune thrombocytopenia (ITP) present with mild symptoms and their
disease spontaneously resolves within 3 to 6 months. However, a subset of pediatric ITP
patients experience severe bleeds and their symptoms persist for more than 6 to 12 months.
Both patient populations present with similarly low platelet counts, making it difficult to
predict the disease course and to decide on a treatment plan. The current American Society of
Hematology treatment guidelines advise that most cases of ITP may be managed through close
observation, while pharmacological interventions that may result in treatment-related
toxicities may be used in patients with more severe bleeding symptoms. In order to improve
the care and management of pediatric patients with ITP, it is necessary to develop a better
predictor of bleeding events and disease severity than the patient's platelet count.

In a previous single-center study, investigators studied the association of different
platelet parameters with patient bleeding severity. Using whole blood from patients diagnosed
with severe ITP, investigators measured the immature platelet fraction (IPF) and absolute
immature platelet count (IPC) through a hematology analyzer (Sysmex XN-1000). Investigators
performed functional tests on the platelets and analyzed them through flow cytometry. In this
study, the investigators found that the IPF and IPC is associated with patient bleeding
severity, independent of platelet count. It was also determined that functional activation
markers such as P-selectin and glycoprotein (GP) IIb-IIIa are significantly associated with
subsequent bleeding severity in children, independent of platelet count. The results of these
proposed studies in ITP patients may suggest clinically relevant uses of these assays.

To confirm these findings, this trial will repeat the previous study in a multi-center
patient population, including a greater number of patients with severe bleeding and low
platelet counts.

Inclusion Criteria:

- Diagnosed with primary or secondary immune thrombocytopenia.

- Platelet count of < 50 x 10^9/L

Exclusion Criteria:

- May not have received aspirin 10 days prior to study entry.

- May not have received nonsteroidal anti-inflammatory drugs (NSAIDs) 3 days prior to
study entry.