Risk Factors for Thrombosis Vary According to Age in Patients with Essential Thrombocythemia: a Retrospective Analysis of 1090 Patients from the “Gruppo Laziale SMPC Ph Negative “,
Authors: Montanaro Marco , Latagliata Roberto , Cedrone Michele , Villivà Nicoletta , Porrini Raffaele , Spirito Francesca , Rago Angela , Crescenzi Sabrina Leonetti , Spadea Antonio , De Muro Marianna , Cotroneo Ettore , Breccia Massimo , De Gregoris Cinzia , Anaclerico Barbara , Felici Stefano , Ruscio Carla , Di Giandomenico Jonny , Franceschini Luca , Pessina Gloria , Cimino Giuseppe , Montefusco Enrico , Majolino Ignazio , Mazzucconi Maria Gabriella , Alimena Giuliana , Andriani Alessandro 
Published: October 2019

Abstract
Abstract 3854
Increasing age is a well-recognised risk factor for thrombotic events in patients with Essential Thrombocythemia (ET): however, few data exist on the role of other clinical and biological features in different age groups. To address this issue, we analysed retrospectively 1090 ET patients (M/F 403/687, median age 63 years, IR 17 – 96) diagnosed at 11 Hematological Institutions in the Lazio region from 1980 to 2010 and with a median period of follow-up of 84 months (IR 1 – 371). Based on the commonly adopted age threshold, 480 patients (44 %) were < 60 years (Group A) and 610 (56 %) were ≥ 60 years (Group B). Clinical and biological features as well as cardiovascular risk factors analyzed for the impact on the thrombotic risk in the two age groups are reported in the Table.Group A < 60 yearsGroup B ≥ 60 yearsPutative risk factorsRisk ratio (95% CI)P valueRisk ratio (95% CI)P valueM/F167/3132.68 (1.03–6.94)0.0029236/3741.12 (0.17–2.59)0.73WBC median (range) x 109/l8.9 (4.29–22.35)0.387 (0.149–1,004)0.06458.9 (1.2–57.7)0.79 (0.41–1.47)0.445PLTS median (range) x 109/l837 (451–3582)0.37 (0.258–1.70)0.66802 (450–3104)0.52 (0.28–0.99)0.0052Hb median, g/dL (range)14.1 (6.0–18.4)0.86 (0.33–2.24)0.76914.0 (7.0–17.8)0.87 (0.45–1.67)0.674*JAK-2 mutational status: wild type/mutated (%)53.2/46.81.57 (0.50–4.87)0.4434.1/65.90.498 (0.17–1.48)0.209Previous thrombotic events: n° (%)· All events72 (15)2.18 (0.59–7.96)0.12149 (24.4)3.01 (1.38–6.57)0.0004· within 24 months from diagnosis48 (10)1.43 (0.19–10.4)0.7464 (10.5)0.506 (0.18–1.39)0.189· within 60 months from diagnosis60 (12.5)NA0.5191 (14.9)0.323 (0.11–0.95)0.023Cardiovascular risk factors: Y/N %○ Arterial hypertension41.7/58.31.68(0.64–4.36)0.2880.7/19.30.96 (0.36–2.57)0.935○ Diabetes10.2/89.81.11 (0.23–5.15)0.8925.0/75.01.09 (0.38–3.11)0.86○ Smoking attitude45.6/54.42.78 (1.01–7.65)0.06758.3/41.71.04 (0.35–3.09)0.94○ Hyperlipidemia31.0/69.03.11(0.917–10.592)0.03951.6/48.42.31 (0.70–7.55)0.203
In Group A, 39 patients (8.1%) had at least one thrombotic event during follow-up; there were 20 (51.3%) arterial thrombosis and 19 (48.7%) venous thrombosis. In Group B, 63 patients (10.3%) had at least one thrombotic event during follow-up; there were 38 (69.4%) arterial thromboses and 25 (39.6%) venous thromboses. In group A univariate analysis for thrombosis-free survival performed by Kaplan-Meier method, disclosed a significant impact of male gender (p=0.0029, CI 1.03–6.94, HR 2.68), > 2 cardiovascular risk factors (p=0.0002, CI 1.87 – 190, HR 18.94) and isolated hyperlipidemia (p=0.039, CI 0.917 – 10.59, HR 3.11), while previous thrombotic events had no significant impact (p=0.27). By contrast, the presence of a previous thrombotic event was the only feature with a significant impact on thrombotic risk in Group B (p=0.0004, CI 1.38 – 6.55, HR 3.01). WBC and PLTS values at different cut-off levels as well as JAK-2 mutational status did not have any impact on thrombosis in either age groups. However, in group B, we observed a trend (p=0.052, CI 0.28–0.99, HR 0.52) towards a protective effect of higher PLTS values (> 800 × 109/l).
In conclusion, our data seem to reinforce the need of a different thrombotic risk assessment in distinct age groups: in particular, younger patients could benefit from early recognition and treatment of well-known cardiovascular risk factors.

Disclosures:
No relevant conflicts of interest to declare.