Cytoreductive
therapy, with or without low-dose
aspirin, is the mainstay of thrombotic risk reduction in patients with
essential thrombocythemia (ET), but the optimal choice of agent remains unclear. The aim of this study was to meta-analyze currently available data comparing
anagrelide to
hydroxyurea for reduction of rates of
thrombosis,
bleeding and death among patients with ET. A literature search for randomized, controlled trials comparing
anagrelide to
hydroxyurea among patients with ET revealed two published studies. Statistical analysis was performed using fixed effects meta-analysis. Rates of
thrombosis were similar between patients treated with
hydroxyurea vs
anagrelide (RR 0.86, 95 % CI 0.64-1.16). Rates of major
bleeding were lower in patients treated with
hydroxyurea (RR 0.37, 95 % CI 0.18-0.75). Rates of progression to
acute myeloid leukemia were not statistically different (RR 1.50, 95 % CI 0.43-5.29). The composite of
thrombosis, major
bleeding and death favored
hydroxyurea (RR 0.78, 95 % CI 0.63-0.97). In conclusion, our analysis supports use of
hydroxyurea as a first-line cytoreductive agent for patients with ET, based largely on decreased rates of major
bleeding.
Anagrelide appears to be equally effective for protection against thrombotic events and may be an appropriate alternative for patients who are intolerant of
hydroxyurea.