Evaluation of WHO criteria for diagnosis of polycythemia vera: a prospective analysis.

We prospectively evaluated the accuracy of the 2007 World Health Organization (WHO) criteria for diagnosing polycythemia vera (PV), especially in "early-stage" patients. A total of 28 of 30 patients were diagnosed as PV owing to an elevated Cr-51 red cell mass (RCM), JAK2 positivity, and at least 1 minor criterion. A total of 18 PV patients did not meet the WHO criterion for an increased hemoglobin value and 8 did not meet the WHO criterion for an increased hematocrit value. Bone marrow morphology was very valuable for diagnosis. Low serum erythropoietin (EPO) values were specific for PV, but normal EPO values were found at presentation (20%). We recommend revision of the WHO criteria, especially to distinguish early-stage PV from essential thrombocythemia. Major criteria remain JAK2 positivity and increased red cell volume, but Cr-51 RCM is mandatory for patients who do not meet the defined elevated hemoglobin or hematocrit value (>18.5 g/dL and 60% in men and >16.5 g/dL and 56% in women, respectively). Minor criteria remain bone marrow histology or a low serum EPO value. For patients with a normal EPO value, marrow examination is mandatory for diagnostic confirmation. Because the therapies for myeloproliferative disorders differ, our data have major clinical implications.