Drug-eluting coronary-artery stents.

n engl j med 368;16 nejm.org april 18, 2013 1557 by Barbui et al., a consensus statement of which they are coauthors, contains no data addressing their assertion because, as Barbui has written elsewhere,1 there are no data implicating the baseline leukocyte count as a thrombotic risk factor in patients with polycythemia vera. Fourth, by choosing the reference by Campbell et al., they are conflating polycythemia vera with essential thrombocytosis, for which baseline leukocytosis has also not been shown to be a thrombotic risk factor.1 More important, unlike phlebotomy, cytoreduction with chemotherapeutic agents, including hydroxyurea, has not been shown to prevent major vessel thrombosis2,3 or even prolong survival in patients with polycythemia vera.2,4 However, these agents, including hydroxyurea, have been shown by evidence-based studies to cause acute leukemia in some patients.4,5 Jerry L. Spivak, M.D.