PDSA e-News: August 30, 2019

Physicians’ Perceptions on Causes of Secondary ITP And the Leading Causes of Misdiagnosis in Both Primary and Secondary ITP

Doctor in laboratoryIn a cross-sectional survey of 1507 ITP patients and 472 physicians across 13 countries, the ITP World Impact Survey (I-WISH) conducted a study to examine physicians’ perceptions of the difficulties inherent in making a diagnosis of ITP.

Physicians enrolled in this study treated an average of 36 patients diagnosed as having ITP, including 18 newly diagnosed ITP patients in the past year. Just under ¾ of the physicians in this study indicated that the exclusion of other disorders was the leading cause of delays in making an accurate diagnosis of ITP. Half of the physicians in the study believed that misdiagnosis was a contributing factor in delayed diagnosis, with a majority reporting that patients were misdiagnosed 1–25% of the time. Access to diagnostic examinations and time required to refer patients to a specialist were also listed as contributors to a delayed diagnosis.

Drug induced thrombocytopenia (DIT) was the most frequent condition misdiagnosed as ITP. DIT, like ITP, is mediated by self-reactive antibodies to platelets, but thrombocytopenia generally resolves when the responsible medication has been identified and discontinued. Other alternative diagnoses were liver disease and myelodysplastic syndrome (MDS).

Another common alternative diagnosis was secondary ITP, in which an ITP-like clinical presentation occurs in the context of another disorder. The two most commonly reported causes of secondary ITP in the study were systemic lupus erythematosus, an autoimmune disease in which body's immune system attacks multiple organs, and chronic lymphocytic leukemia (CLL) in which patients seemingly paradoxically develop autoantibodies in the setting of low overall production of antibodies in general.

Other reported causes of secondary ITP include antiphospholipid syndrome, an autoimmune disorder associated with thrombosis, infection (e.g. hepatitis C virus, HIV, Helicobacter pylori), inherited disorders of immune function that become evident post-therapy, and Evans syndrome in which immune damage to red blood cells accompanies ITP.

It is important to make the diagnosis of secondary ITP in a timely manner. Although the management of secondary immune thrombocytopenia may overlap with the management of ITP, there are important differences in approach and the need to treat the responsible underlying condition.



Illustration of platelets in the bloodRetrospective Study Examines The Treatment Results of Sequentially Switching Thrombopoietic Receptor-Agonists In Immune Thrombocytopenia Patients

There is limited data currently available to ascertain the outcome of switching treatment among thrombopoietic receptor-agonists (TPO-ra). This study reviews outcomes in 33 patients with ITP who switched between Romiplostim and Eltrombopag either as a result of ineffectiveness or an adverse effect ascribed to the initial TPO-ra.

Partial response defined >50x109/l without platelet transfusions and bleeding, was seen in 84% of patients who transferred treatment from Eltrombopag to Romiplostim and 47% of patients whose treatment was switched from Romiplostim to Eltrombopag. Complete response, defined >100x109/l without platelet transfusions and bleeding, was reported in 63% of patients whose treatment was switched from Eltrombopag to Romiplostim and 30% of patients who transferred treatment from Romiplostim to Eltrombopag. Roughly a fourth of patients switching to a second TPO-ra therapy did not achieve a response.

This outcome is encouraging although a larger number of patients will need to enrolled to obtain a better gauge on the potential benefits of such changes in therapy. Other studies have reported similar benefits to switching agents.



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