Table 2.

Stratification of risk of survival in polycythaemia vera according to the classical risk score.

Risk Factor	Score
Age ≥ 67 years	5
Age 57–66 years	2
Leukocytes ≥ 15 × 109/L	1
Venous thrombosis	1

Low risk: score 0, intermediate risk: score 1 or 2, high risk: score ≥ 3 (adapted from [129]).