PB2212 FACING ERYTHROCYTOSIS: RESULTS OF AN INTERNATIONAL PHYSICIANS’ SURVEY
Authors: E. Rumi, M. F. McMullin, C. Harrison, M. H. Ellis, M. Barzilai, N. Sarid, R. Mesa, C. Paoli, A. Angona, E. Sant’Antonio, V. V. Ferretti, C. Cavalloni, I. C. Casetti, T. Barbui
Journal: HemaSphere (2019)

Background: Erythrocytosis is diagnosed when the haemoglobin (Hb) and/or haematocrit (Hct) is above the normal range for the subject age and sex. The new 2016 WHO criteria for diagnosis of polycythemia vera (PV) has lowered the Hb or Hct thresholds to 165 g/l or 49% in men and 160 g/l or 48% in women. The number and order of tests to investigate erythrocytosis may vary in different centers. While PV has a well-known treatment algorithm, which involves the use of aspirin and phlebotomy to keep the Hct below 45% in all patients, and cytoreduction for high risk patients, there is no consensus regarding the best way to manage patients with secondary erythrocytosis (SE) or idiopathic erythrocytosis (IE). Aims: To describe the standard practice of haematologists who regularly treat patients with myeloproliferative neoplasms (MPNs) when dealing with erythrocytosis. Methods: An online survey was distributed by email to clinical haematologists practicing in Spain, Israel, USA, Italy, United Kingdom, Austria, and Ireland. We focused on the criteria used to define erythrocytosis, the examinations performed to identify the cause of erythrocytosis, and the treatment used in 5 clinical scenarios of SE or IE (Figure 1). Results: 134 physicians responded to the survey: 35 from Spain, 32 from Israel, 26 from USA, 23 from Italy, 13 from UK and 5 from other countries. There is a general agreement (101 out of 134 physicians, 75.4%) in the use of lower thresholds for Hb to diagnose erythrocytosis, according to the new 2016 WHO criteria. Only 14 physicians (10.4%) still use the old 2008 WHO criteria (> 185 g/l in men and > 165 g/l in women). A small subgroup of 19 physicians (14.2%), mainly from UK and Ireland, uses the British criteria (Hct >52% in men and >48% in women). Most of physicians do not have access to red cell mass evaluation (95 of 134, 70.9%). There is a good agreement in the use of bone marrow biopsy (BMB) in the diagnostic work-up of a patient with a suspect of MPN. Half of physicians (64 out of 134, 47.8%) perform BMB in all cases, a quarter of physicians (34 out of 134, 25.4%) perform BMB only in cases with suspected essential thrombocythemia or primary myelofibrosis. The remaining 26.8% perform BMB in selected cases. The use of BMB significantly differs across countries (P < 0.001), being performed by 91.3% of physicians in Italy, 61.5% in USA, 37.1% in Spain, 28.1% in Israel, and 15.4% in UK. There is variability regarding tests used as “step 1” or “step 2” investigations to evaluate an absolute erythrocytosis. At least half of physicians use as first line assessments for erythrocytosis the following tests: full blood count, erythropoietin, JAK2 V617F mutation, arterial oxygen saturation, serum ferritin, and renal and liver function tests. Responses regarding step 2 investigations are more heterogenous, with only exon 12 JAK2 mutations, BMB and sleep study performed by more than 50% of physicians. The most prominent finding regarding the 5 clinical scenarios is the marked heterogeneity of approaches to both SE and IE: there is a marked variability in the Hct used as target for phlebotomy (ranging from 50 to 56%) and in the use of anti-platelet agents, as reported in Figure 1, although results might be biased by the numbers of respondents.Summary/Conclusion: Our study demonstrates a good agreement among haematologists regarding the use of the new WHO 2016 criteria and the importance of BMB but reveals marked heterogeneity in treatment practice regarding Hct threshold and the use of anti-platelet agents in both secondary and idiopathic erythrocytosis.