RESUMO
The clinical course of essential thrombocythaemia (ET) is mainly outlined by a predisposition to both thromboembolic, and more rarely, haemorrhagic complications. The individual clinical course is, however, variable, ranging from an event-free course to life-threatening thromboembolic episodes. In order to treat ET patients economically, it is necessary, above all, to consider if cytoreductive therapy is really indicated. Risk stratification according to clinical criteria such as age, previous ET-related events and platelet count may help to define patients at risk. In low-risk ET patients, a watch-and-wait strategy seems to be feasible. There is a clear indication for cytoreductive therapy in high risk ET patients as demonstrated in a Phase III clinical trial. Because of the lack of Phase III trials, it is not clear which of the cytoreductive drugs - hydroxyurea, pipobroman, IFN-alpha, pegylated-IFNs or anagrelide - is the best therapeutic option. Factors that influence the choice out of the available drugs are efficacy, safety and cost. The efficacy and safety data of the available drugs for ET are derived from Phase II studies or observational studies. IFN-alpha is the most expensive drug. Newer drugs like anagrelide or pegylated-IFNs are still expensive, but may have a better cost-benefit effect in patients < 60 years of age. Two cost-effectiveness analyses revealed a result in favour of anagrelide, however, in these cost-effectiveness models, assumptions were based on non-randomised trials. For patients > 60 years of age, hydroxyurea may be the best therapeutic option with regard to both the efficacy and cost-effectiveness.
