Contribution of lowered hemoglobin threshold value in the diagnosis of polycythemia vera: Comparison of 2016 and 2008 WHO criteria

Polycythemia vera (PV) diagnosis remains a difficult task despite various updates in the 2016 World Health Organization (WHO) diagnostic criteria compared to 2008 criteria. This study aimed to examine the biochemical and clinical features of patients diagnosed with PV using the WHO 2016 criteria but would have been missed by the WHO 2008 criteria, and to ascertain the impact of the lowered thresholds on PV diagnosis. A total of 229 patients with suspected myeloproliferative neoplasms were included in this cross sectional study. The study group was divided with regard to hemoglobin values. Group A consisted of 126 patients with hemoglobin values of ≤ 18.5 g/dL in males and ≤ 16.5 g/dL in females. Group B comprised 103 patients with hemoglobin values of > 18.5 g/dL in males and > 16.5 g/dL in females. The number of PV diagnoses increased to 145 from 87 (increased by 66.67%) when the 2016 diagnostic criteria were employed rather that the 2008 criteria. Mean age and the frequency of female subjects were lower in Group A compared to Group B. The groups were similar in terms of chronic obstructive pulmonary disease/obstructive sleep apnea syndrome, spleen status, smoking status, and mean corpuscular volume, white blood count, neutrophil, eosinophil and platelet values. red blood cells and lactate dehydrogenase values were significantly higher, while lymphocyte counts were significantly lower in Group B. With the introduction of WHO 2016 criteria, we found a significant increase in the number of patients who were candidates for PV testing and were ultimately diagnosed with PV. These findings support the diagnostic value of the 2016 WHO criteria, and by extension, the lowered thresholds for detection of patients requiring further analysis.