An underestimated blood parameter before myeloproliferative neoplasm diagnosis: The case of thrombocytosis and the delayed essential thrombocytemia diagnosis

Background: Thrombocytosis, i.e. platelet count >400.000/?L in peripheral blood, is also due to Essential Thrombocythemia (ET), and delaying the diagnosis of thrombocytosis might coincide with a delayed ET diagnosis. The purpose of our study was to investigate the factors virtually leading to a delay in ET diagnosis. Methods: We analyzed the interval between the first evidence of thrombocytosis and ET diagnosis, and defined it as ET-underestimation-period (ET-uP). We analyzed 280 ET patients followed at our Institution. To verify possible correlations with ET-uP, we investigated patients' ages, gender, history of vascular complications, thrombocytosis, splenomegaly, and marrow fibrosis degree. We also considered their General Practitioners (GP) characteristics: age, personal computer use, number of patient visits in the two years before diagnosis. Univariate logistic analysis for each parameter was performed using the Spearman's rank correlation coefficient to assess correlation with ET-uP. Multivariate logistic regression analysis was performed on the parameters that resulted significant at the previous analyses. The logistic regression analysis was performed dichotomizing the ET-uP variable using its median value. Results: Median ET-uP was 16 months (range 1-240). The analysis showed that a shorter ET-uP correlated with thrombocytosis (p<0.001) and previous cardiovascular events (p=0.04). At multivariate analysis, the Area. Under the Curve (AUC) of the (Receiver Operating Characteristic) ROC curve was 0.72. No correlation was found analyzing GP data. Conclusion: Our results underline a deficient medical practice, and prompt for corrective actions (use of more restrictive normal range for platelet count-with lower upper limit and warning flags for pathological findings) to timely commence the diagnostic workup of this condition.