The previous guideline was published in 2005 (McMullin et al, 2005) with an amendment in 2007 (McMullin et al, 2007) to update the diagnostic criteria following the discovery of the JAK2 mutation in patients with polycythaemia vera (PV). Since that time, there has been a considerable amount of research in the area concerning diagnostics, risk stratification, new agents and reinvestigation of existing agents. It was therefore decided to evaluate the literature to formulate guidance on the diagnostic pathway for erythrocytosis, risk stratification of PV, management of PV (including specific situations) and the management of secondary erythrocytosis.

Here we provide evidence‐based guidance on diagnosis, risk stratification and management of PV. Our review of the evidence led us to some differences in diagnostic criteria and risk stratification than have been proposed by other international organisations. We discuss the reasons for this. An accompanying guideline looks at management of specific situations in PV and management of secondary erythrocytosis (McMullin et al, 2018).

Declaration of Interests

The BSH paid the expenses incurred during the writing of this guidance. None of the authors had conflicts of interest to declare. All authors have made a declaration of interests to the BSH and Task Force Chairs which may be viewed on request.