[Vascular complications of polycythemia].

The vascular risk factors of patients with polycythemia rubra vera was assessed by reviewing the results of international therapeutic studies. The risk factors were: an age over 60, previous vascular problems, the quality of follow-up (maintenance of hematocrit below 50 p. cent and platelet count below (600.10(9)/l). The treatment is one of the most important factors: the risk of vascular complications was three times greater in patients treated by venesection, al other factors being equal. This counter-balanced the higher risk of leukemia in patients treated by myelo-depression. The use of platelet anti-agregant drugs remains controversial. Recent results question their efficacy in preventing thrombosis and emphasise the risk of hemorrhage. The results of platelet factor 4 (PF4) and beta-thromboglobin (beta TG) levels provide further information for judging the vascular risk of these patients, and may, in prospective studies, give a better assessment of the efficacy of platelet anti-agregant drugs in vivo.