Sex and age as prognostic factors in essential thrombocythemia.

BACKGROUND. The major causes of morbidity and mortality in essential thrombocythemia (ET) are bleeding and thrombotic accidents, but a prognostic pattern for these complications has not yet been discovered. MATERIALS AND METHODS. In this study we report data from a large cohort of patients with thrombocytosis, distinguished for sex and age, in order to define their thrombotic risk. The prevalence of vascular complications recognized in 86 patients with essential thrombocythemia was studied. In addition, 91 patients with polycythemia vera (PV), 20 with myelofibrosis (MF) and 63 with secondary thrombocytosis (ST) were evaluated. RESULTS. 6.3% of ET subjects younger than 40 (4.6% of males and 7.0% of females), 11.8% of patients between 40 and 65 years old (14.9% of males and 9% of females), and 16.8% of subjects over 65 (14.6% of males and 17.8% of females) showed thrombotic accidents. In the PV and MF groups thromboses occurred more frequently than in the ET groups for all ages and for both sexes. On the contrary, ST subjects showed fewer thromboses than ET patients, but their incidence rose with patient age; moreover the prevalence of males in this group was limited. In ET patients, particularly in females, the incidence of thrombosis was low under 40 years of age, but rapidly increased later. CONCLUSIONS. ET females over 40 must be followed with particular attention in order to prevent thrombotic complications.