Common Themes and Uncertainties in Management of Secondary Polycythaemia: An International Clinician Survey of Practice.

Introduction: Secondary and idiopathic polycythaemia is far more common than polycythaemia vera. Whilst venesection for polycythaemia vera has a robust evidence base, the data supporting this treatment for secondary and/or idiopathic polycythaemia are limited to small single-arm studies showing transient improvement in symptoms or physiologic endpoints. As a result the British Society for Haematology Guideline for the management of specific situations in polycythaemia vera and secondary erythrocytosis suggests considering venesection in patients with hypoxic lung disease with Hct > 0.56 or to a target Hct < 0.55 in those with idiopathic polycythaemia. We hypothesised that this paucity of evidence results in widespread variation in management of secondary polycythaemia. Methods: To assess attitudes and practice in the treatment of secondary and idiopathic polycythaemia we designed an international clinician survey to evaluate current practice and define the point of clinical equipoise at which clinicians would be content to enter patients into a randomised venesection study. This survey was distributed using the wide-reaching HaemSTAR research network. Results: A total of 123 clinicians responded, of which 90 were experienced senior clinicians. 62% reported not routinely offering regular venesection whereas 38% of respondents did. Those considering venesection rose to ∼2/3 of respondents in specific circumstances such as polycythaemia-related symptoms, previous arterial or unprovoked venous thrombosis. Respondents were more likely to offer venesection to patients with idiopathic- compared to androgen- or hypoxia-driven polycythaemia. Of those who would venesect, most would use a threshold Hct ≥ 0.55, with a target Hct < 0.55 but there was significant variability. Conclusions: Our survey showed considerable variability in venesection practice for patients with secondary or idiopathic polycythaemia, probably reflecting the paucity of the evidence base. There was widespread support for a trial of venesection vs observation in secondary polycythaemia and this survey has helped to define the threshold Hct at which clinical equipoise exists.