Author: Jacques Zimmer
Position: MD, PhD, Research Scientist
Institution: Laboratory of Immunogenetics and Allergology, CRP-Sante, Luxemburg
E-mail: jacques.zimmer@crp-sante.lu
Additional Authors: Francois Hentges, MD (Laboratory of Immunogenetics and Allergology, CRP-Sante, Luxemburg); Emmanuel Andres (Internal Medicine Service, Medical Clinic B, Hospital Universities of Strasbourg, France)
Submitted Date: May 11, 2006
Published Date: May 22, 2006
This comment was originally posted as a “Reader Response” on the publication date indicated above. All Reader Responses are now available as comments.

We read with interest the paper by Stasi et al. [1] about the follow-up of patients with a so-called borderline thrombocytopenia with platelet numbers of 100 - 150 x 109/l. Data about the long term outcome of such patients are indeed not frequent in the literature, as the authors claim, but some information has nevertheless previously been published, as in our retrospective study on adult ITP [2] not cited by Stasi et al. [1].

Our cohort was composed of 201 ITP patients separated in treated and untreated individuals. The latter group was composed of 62 patients (30.8 % of the cohort) with a sex ratio women/men of 3.1/1 and a mean age of 39 years. The vast majority (54 patients, 87.1 % of the untreated) was referred to the hospital because of mild isolated thrombocytopenia discovered on routine laboratory examination. These patients were asymptomatic and considered apparently healthy. In 8 other cases (12.9 %) however, a single, moderate and spontaneously regressive bleeding episode occurred: purpura (n = 4), epistaxis (n = 1), gingivorraghia after tooth extractions (n = 1) and meno-and metrorrhagia (n = 2) in two women with IUD and uterine polyps, respectively. The mean platelet count among these patients was 62 x 109/l, compared to 88 x 109/l for the entire untreated group. ANA were tested in 46 cases (74.2 %), with significantly positive values in 6 patients (13 % of the tested individuals).

During the follow-up period of 1.9 - 59 months, no further bleeding occurred in the 8 patients with initial moderate hemorrhage, although 6 of them remained thrombocytopenic for more than 6 months. None of the asymptomatic individuals developed any hemorrhagic symptoms. A chronic ITP (isolated thrombocytopenia of at least 6 month duration) was diagnosed in 31 patients (59 %) with a mean platelet count of 66 x 109/l. No autoimmune or hematologic disease (other than ITP) developed in this group. Twenty-three patients were readdressed to their family physicians for further surveillance and lost to follow-up.

According to current guidelines for the management of adult ITP [3,4], patients with platelet numbers > 50 x 109/l are usually not treated. The stable and moderate evolution of the thrombocytopenia in our patients confirms the validity of this attitude. That we did not observe the development of other autoimmune diseases in contrast to the small number of such cases noticed by Stasi et al. [1] might be related to the smaller size of our cohort and/or the shorter follow-up period. As these authors define ITP as a persistent platelet count below 100 x 109/l and not 150 x 109/l as we did, a direct comparison of the results might be difficult. If a patient with platelet counts under 150 x 109/l but above 100 x 109/l is considered to have ITP or borderline thrombocytopenia is an academic question rather than a point of clinical importance, because the medical strategy is exactly the same (surveillance of platelet counts in the absence of any treatment). This holds true for patients with platelets between 50 - 100 x 109/l that would be classified as ITP cases according to Stasi et al. [1]. Thus, it is not obvious why an additional clinical entity (borderline thrombocytopenia) should be created in addition to ITP.

References
1. Stasi R, Amadori S, Osborn J, Newland AC, Provan D (2006) Long-term outcome of otherwise healthy individuals with incidentally discovered borderline thrombocytopenia. PloS Med 3: 388-394.
2. Zimmer J, Andres E., Noel E, Koumarianou A, Blickle JF, Maloisel F (2004) Current management of adult idiopathic thrombocytopenic purpura in practice: a cohort study of 201 patients from a single center. Clin Lab Haematol 26: 137-142.
3. Cines DB, Blanchette VS (2002) Immune thrombocytopenic purpura. N Engl J Med 346: 995-1008.
4. Provan D, Newland A (2002) Fifty years of idiopathic thrombocytopenic purpura (ITP): management of refractory ITP in adults. Br J Haematol 118: 933-944.