Anagrelide compared with hydroxyurea in essential thrombocythemia: a meta-analysis

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.