Treating patients with polycythemia vera (PV)
When monitoring hematocrit (Hct),
keeping levels below 45% made a difference
in the rate of thrombotic complications
> In a study published in The New England Journal of Medicine in 2013, 365 adult patients with
PV were randomized into 2 groups1:
More-intensive treatment,
n = 182, target Hct <45% (low Hct)
Less-intensive treatment,
n = 183, target Hct 45% to 50% (high Hct)
The rate of cardiovascular death and major thrombosis was ≈4-fold higher with
Hct level of 45% to 50% compared with Hct level of <45%
Rate of Cardiovascular Death and Major Thrombosis:
Study Published in The New England Journal of Medicine, 2013
Probability of Remaining Event-free
Primary End Point: Death From Cardiovascular Causes or Thrombotic Events
1.0
Low Hct (<45%)
P = 0.004 by log-rank test
0.9
High Hct (45% to 50%)
0.8
Hazard ratio
Low Hct
High Hct
0.7
0.0
0
Number at risk
Low Hct
182 (0)
High Hct
183 (6)
6
5/182 (2.7%)
18/183 (9.8%)
12
18
1.00
3.91 (95% CI, 1.45%-10.53%)
24
30
36
42
48
95 (0)
92 (2)
62 (0)
54 (1)
18 (0)
12 (0)
0
1
Months
177 (1)
168 (0)
168 (2)
160 (3)
154 (1)
143 (4)
129 (1)
110 (2)
Adapted with permission from Massachusetts Medical Society.
> In this randomized clinical trial:
•
•
•
•
•
•
Baseline characteristics were balanced between both groups
≈50% had received an initial diagnosis of PV within 2 years before randomization
67.1% we re at high risk because of advanced age or previous thrombosis
Therapy options for maintaining Hct levels were phlebotomy, cytoreductive drugs, or both
The composite primary end point was the time until death from cardiovascular causes or major thrombotic events
Platelet levels did not differ in the 2 arms, whereas white blood cell counts persisted at significantly higher levels
in the high-Hct group compared with the low-Hct group (P < 0.001)
Reference: 1. Marchioli R et al. N Engl J Med. 2013;368(1):22-33.