Risk Factors for Thrombosis in Patients Aged > 60 Years with Essential Thrombocythemia without Previous Thrombotic Events

Background Thrombotic events are the major complications in patients (pts) with Essential Thrombocythemia (ET). Occurrence of thrombotic events before ET diagnosis is a worldwide recognised risk factor for thrombosis in the follow-up of ET pts: age > 60 years is another risk factor, but its role in pts without previous thrombotic events needs to be further defined with the addition of other potential risk factors.

Methods To assess prognostic role of different putative risk factors for thrombosis in a wide cohort of elderly pts, we revised clinical features, follow-up and thrombotic events in 956 ET pts aged > 60 years diagnosed from 1/2000 to 12/2016 and enrolled in the retrospective and prospective registries of Latial Group for the Study of Myeloproliferative Neoplasms.

Results On the whole, 191/956 pts (20.0%) (Group A) had a story of previous thrombotic events before ET diagnosis (arterial in 139 pts and venous in 52 pts): of them, 27 had at least one thrombotic event in the ET follow-up, with a 3- and 5-year cumulative incidence of thrombosis of 10.7% (95%CI 5.8 - 15.6) and 18.8% (95%CI 11.8 - 25.8), respectively. Among the remaining 765 pts (80.0%) without any thrombotic event before ET diagnosis (Group B), 59 reported at least one thrombotic event, with a 3- and a 5-year cumulative incidence of 2.7% (95%CI 1.6 - 3.8) and 5.7% (95%CI 3.8 - 7.6), respectively. The main clinical features at ET diagnosis of the entire cohort and according to the occurrence of previous thrombosis before ET diagnosis were reported in the Table: pts in the Group A had a higher WBC median value and a higher rate of dyslipidaemia compared to pts in the Group B. The following putative risk factors for thrombosis were evaluated in the Group B pts: gender, age>75 years, WBC, PLTs, Hb, spleen enlargement, JAK-2-V617F mutation and allele burden, hypertension, diabetes, smoke attitude, dyslipidaemia). Only the presence of hypertension showed a prognostic significance (3- and 5-year cumulative incidence of thrombosis of 4.7% and 8.2%, respectively, vs 0.6% and 3.1% in pts without hypertension, p=0.016).

Conclusions While previous thromboses before ET diagnosis and age > 60 years are generally regarded in a similar way as thrombotic risk factors, the risk related to age > 60 years per se seems lower: in addition, in ET pts aged > 60 years without previous thrombosis, only hypertension seems to have a predictive role and needs to be carefully controlled.

Latagliata:BMS: Honoraria; Novartis: Honoraria. Breccia:Novartis, Incyte, Pfizer, BMS, Abbvie: Honoraria. Abruzzese:BMS, Incyte, Novartis, Pfizer: Consultancy. Rossi:Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. De Stefano:AbbVie: Honoraria; Amgen: Honoraria, Speakers Bureau; Bristol Myers Squibb/Celgene: Honoraria, Speakers Bureau; GlaxoSmithKline: Honoraria, Speakers Bureau; Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees.