JAK2 and deep vein thrombosis: This slowly evolves to a 3-tiered prognostic model based on multivariable-analysis-derived HR to age > 60 years (HR = 1.5; 1 point), thrombosis history (HR = 1.9; 2 points), cardiovascular risk factors (HR = 1.6; 1 point), and JAK2 V617F (HR = 2.0; 2 point) into either low risk < 2 points; intermediate risk = 2 points or high risk > 2 points [33].