A new adjudication process has been proposed by Canadian researchers to potentially increase the classification accuracy of immune thrombocytopenia (ITP). The process was published and detailed in the journal Thieme Open Access.

Without clear biomarkers or specific clinical criteria, a diagnosis of ITP can be difficult to reach, requiring the exclusion of other diseases first, the researchers noted. The adjudication criteria include a number of different diagnoses including mild thrombocytopenia, primary ITP, secondary ITP, drug-induced ITP, nonimmune thrombocytopenia, and other thrombocytopenia disorders, they added.

Read more about ITP diagnosis

For primary ITP, the criteria include a platelet count of <100 x 109/L with no other diagnosis. The patient should also have a platelet response to corticosteroids or high-dose intravenous immunoglobulin treatment. If the response results in a platelet increase greater than 100, then the diagnosis should remain ITP.

A diagnosis of secondary ITP should remain even if the underlying cause is treated and the ITP persists except for the pregnancy-associated ITP. If the ITP was present before pregnancy or persists post-partum then a diagnosis of primary ITP should be made. Gestational thrombocytopenia usually involves a platelet count of above 70 x 109/L during pregnancy, normalization of platelets after pregnancy, and no thrombocytopenia in the fetus or newborn.

“The process for establishing the clinical diagnosis of thrombocytopenic disorders is not standardized, prone to ascertainment bias, and influenced by provider and region. To improve diagnostic accuracy, we developed an adjudication process for patients with thrombocytopenic disorders,” the authors wrote.

The adjudication process was developed using patient data from the McMaster ITP Registry, a longitudinal, prospective single-center study of consecutive adult patients presenting for investigation of thrombocytopenia to the tertiary hematology clinic at McMaster University in Canada.

Patients were enrolled between January 2010 and December 2019 and were followed prospectively every 6 months until discharge or death. A total of 789 patients were enrolled in the registry including 157 who met the criteria for adjudication, which consisted of a change in diagnosis, no clear cause of thrombocytopenia identified, and thrombocytopenia appearing in the context of pregnancy.


Gabe C, Mahamad S, St John M, Duncan J, et al. Adjudicating the diagnosis of immune thrombocytopenia in a clinical research study. TH Open. Published online April 28, 2023. doi:10.1055/s-0043-57226