Risk stratification in PV and ET based on thrombotic risk
Risk category
.
Age >60 y or history of thrombosis
.
Low
No
High
Yes
Risk category
.
Age >60 y or history of thrombosis
.
Low
No
High
Yes
Extreme thrombocytosis (platelet count >1500 × 109/L) is a risk factor for bleeding, not for thrombosis. Both increasing leukocyte count and JAK2 V617F mutation or allele burden have been identified as novel risk factors for thrombosis, but confirmation is required.