【medical-news】NEJM:真性红细胞增多症的高强度治疗可减少心血管死亡

http://www.nejm.org/doi/full/10.1056/NEJMoa1208500
BACKGROUND
Current treatment recommendations forpatients with polycythemia vera call for maintaining a hematocrit of less than45%, but this therapeutic strategy has not been tested in a randomized clinicaltrial.
METHODS
We randomly assigned 365 adults withJAK2-positive polycythemia vera who were being treated with phlebotomy, hydroxyurea,or both to receive either more intensive treatment (target hematocrit, <45%)(low-hematocrit group) or less intensive treatment (target hematocrit, 45 to50%) (high-hematocrit group). The primary composite end point was the timeuntil death from cardiovascular causes or major thrombotic events. Thesecondary end points were cardiovascular events, cardiovascularhospitalizations, incidence of cancer, progression to myelofibrosis,myelodysplasia or leukemic transformation, and hemorrhage. An intention-to-treatanalysis was performed.
RESULTS
After a median follow-up of 31 months, theprimary end point was recorded in 5 of 182 patients in the low-hematocrit group(2.7%) and 18 of 183 patients in the high-hematocrit group (9.8%) (hazard ratioin the high-hematocrit group, 3.91; 95% confidence interval [CI], 1.45 to10.53; P=0.007). The primary end point plus superficial-vein thrombosisoccurred in 4.4% of patients in the low-hematocrit group, as compared with10.9% in the high-hematocrit group (hazard ratio, 2.69; 95% CI, 1.19 to 6.12;P=0.02). Progression to myelofibrosis, myelodysplasia or leukemictransformation, and bleeding were observed in 6, 2, and 2 patients,respectively, in the low-hematocrit group, as compared with 2, 1, and 5patients, respectively, in the high-hematocrit group. There was no significantbetween-group difference in the rate of adverse events.
CONCLUSIONS
In patients with polycythemia vera, thosewith a hematocrit target of less than 45% had a significantly lower rate ofcardiovascular death and major thrombosis than did those with a hematocrittarget of 45 to 50%.