Immune Thrombocytopenia: An Atlantic Divide in Nomenclature?

Dear editor,

We read with great interest, the letter from Turgutkaya et al. [1], which was an elegant elucidation of the pathogenesis of immune thrombocytopenia (ITP) and celiac disease. They had also suggested that based on pathogenesis, the terminology autoimmune thrombocytopenia (AIT) should be used instead of immune thrombocytopenia to better describe the autoimmune nature of ITP in our article [2]. This stimulated us to do an extensive literature review on the nomenclature and terminology of ITP. Immune thrombocytopenia is the widely accepted and commonly used terminology to describe ITP in the various international guidelines [3–4].

To further analyse the usage of the two terms we performed a PubMed database search for articles whose title contained the words “Immune thrombocytopenia”. There were 2199 results for the search, in which 486 articles have been published since 2018. These articles were further analysed based on the country of origin of the first author of the article. Authors from forty-six countries have published literature on ITP in 2018–2020, the distribution of which is shown in Fig. 1. Around 40% of all articles originated from China or USA, and the remaining 60% were distributed widely across many countries.

Fig. 1.

ITP publications classified as per country of origin

A similar PubMed search was performed for the term “autoimmune thrombocytopenia” in the article title. There were a total of 353 articles of which only 14 were published since 2018. Interestingly only 5 of these 14 articles were published by authors whose primary area of expertise was in Internal Medicine or Hematology. The remaining articles belonged to authors in other specialities like dermatology, rheumatology or gynaecology. In view of small numbers using the term AIT, we extended the search to involve articles published since 2010. A total of 42 articles were identified, which originated from 18 different countries. However, a closer analysis of the same revealed that 57% of the articles using the name ‘autoimmune thrombocytopenia’ were from Europe. Only 18 articles originated from outside Europe.

Our analysis suggests that Immune thrombocytopenia is the commonly accepted term to describe primary ITP. The use of the terminology Autoimmune thrombocytopenia is possibly restricted to European countries. Even in the publications from European countries, the term ITP was used more frequently than AIT. While we accept that the use of PubMed, a North-American based database may have skewed our results and contributed to a selection bias, the use of the term Immune thrombocytopenia in all international guidelines [3–4] suggests that the same trend is likely to be shown with the analysis of other databases as well.

According to the International Working Group (IWG) guidelines for ITP, Isolated thrombocytopenia in the absence of other causes of thrombocytopenia is categorised as primary ITP. All other immune mediated thrombocytopenia’s are classified as secondary ITP [4]. We analysed the articles found in our search which used the term autoimmune thrombocytopenia, as per this guideline. Eight out of the fourteen publications which used AIT, used it to describe secondary ITP, which seem to directly contradict the suggestion made by Turgatkaya et al. [1] that AIT represents only primary ITP.

In her correspondence on nomenclature of chronic myeloid leukemia and ITP, Bain agrees that ITP [5] is an imprecise name and that AIT is pathophysiologically more accurate. She also argues that frequent name changes of diseases lead to confusion among patients and non-hematologists. Using this argument and based on our literature review, we advocate avoiding the term autoimmune thrombocytopenia and following the more widely used term, namely Immune thrombocytopenia. We as haematologists should also advocate the usage of the standardised IWG nomenclature among the health professionals from other specialities. This will enable the use of a uniform terminology to describe this common disease.