The Role of Previous Thrombotic Events in Patients with Essential Thrombocythemia: The Earlier the Worse?
Authors: Latagliata Roberto , Montanaro Marco , Cedrone Michele , Villivà Nicoletta , Porrini Raffaele , Spirito Francesca , Rago Angela , Crescenzi Sabrina Leonetti , Spadea Antonio , De Muro Marianna , Cotroneo Ettore , Breccia Massimo , Baldacci Erminia , De Gregoris Cinzia , Anaclerico Barbara , Felici Stefano , Ruscio Carla , Giandomenico Jonny Di , Franceschini Luca , Pessina Gloria , Cimino Giuseppe , Montefusco Enrico , Tafuri Agostino , Avvisati Giuseppe , Majolino Ignazio , Mazzucconi Maria Gabriella , Alimena Giuliana , Andriani Alessandro 
Published: October 2019

Abstract
Abstract 5062
Thrombotic events occurring before or at diagnosis of Essential Thrombocythemia (ET) are a worldwide recognized prognostic factor for the incidence of thrombosis during the follow-up of ET patients: however, these previous thrombotic events have been considered on the whole in the vast majority of studies, without further characterization. Among 1063 ET patients collected in the retrospective database of the “Gruppo Laziale SMPC Ph-”, we revised 186 cases with a previous thrombosis and a known data of occurrence, to evaluate the role of the interval from previous thrombotic episode and the diagnosis of ET. In 95 patients (51. 1%) previous thrombotic event occurred < 24 months before diagnosis of ET (group A) while in 91 patients (48. 9%) thrombosis occurred ≥ 24 months before diagnosis of ET (group B). Clinical features of patients at diagnosis are shown in the Table:
GROUP A GROUP B p Gender (M/F) 40/55 42/49 0.636 Median age (yrs) (Interquartile range) (IR) 64.1 (52.7–71.8) 70.9 (61.0 – 78.0) 0.001 Hb median (g/dl) (IR) 13.9 (12.5 – 14.7) 14.2 (13.0 – 15.2) 0.136 PLT median (x 109/l) (IR) 800 (669 – 1066) 778 (652 – 926) 0.453 WBC median (x 109/l) (IR) 9.2 (7.8 – 11.3) 8.6 (7.1 – 10.8) 0.121 Median interval diagnosis – CHT (mos) (IR) 0.9 (0 – 7.0) 1.7 (0.4 – 5.6) 0.194 *CV risk factors (n°/%): 0.454     0 20 (21.0) 17 (18.6)     1 42 (44.2) 44 (48.3)     ≥ 2 33 (34.8) 30 (33.1) Type of previous thrombosis (n°/%): 0.873     Arterial 78 (82.1) 67 (73.6)     Venous 17 (17.9) 24 (26.4) * Cardiovascular (CV) risk factors at diagnosis were considered the presence of arterial hypertension, diabetes, smoking attitude, and hypercholesterolemia. In the group A, 9 out 95 patients (9. 4%) reported thrombotic episodes (5 arterial and 4 venous) during follow-up compared to 23 out 91 patients (25. 2%) (13 arterial and 10 venous) in the group B (p=0. 004). Consequently, patients of group B had a significantly higher cumulative risk of thrombosis compared to patients of group A (p=0. 0029, CI95% 1. 5 – 6. 1, RR 3. 04). In addition, it is worth of note that there was no difference in the cumulative risk of thrombosis between the patients of group A and the 877 patients without previous thrombotic events (p=0. 303, CI95% 0. 64 – 3. 21, RR 1. 24) In conclusion, the prognostic role of a previous thrombotic event in ET patients seems to be related not to the occurrence per se of the event but mainly to the interval between the event and the diagnosis of ET.

Disclosures:
Tafuri: Sigma Tau Pharmaceuticals: Research Funding.