The importance of cardiovascular risk factors for thrombosis prediction in patients with essential thrombocythemia.

The current widely accepted stratification defined by age and previous thrombosis in patients with essential thrombocythemia (ET) probably deserves deeper analysis. The aim of our study was to identify additional factors at the time of diagnosis, which have an impact on the thrombosis prediction. We conducted a study of 244 consecutive ET patients with median follow-up of 83 months. We analyzed the influence of age, gender, laboratory parameters, history of previous thrombosis, spleen size, JAK2 mutation as well as cardiovascular (CV) risk factors including arterial hypertension, diabetes, active tobacco use and hyperlipidemia in the terms of thrombosis. The most important predictors of thrombosis in multivariate Cox regression model were the presence of CV risk factors (p=0.004) and previous thrombosis (p=0.038). Accordingly, we assigned risk scores based on multivariable analysis-derived hazard ratios (HR) to the presence of 1 CV risk factor (HR=3.5; 1 point), >1 CV risk factors (HR=8.3; 2 points) and previous thrombosis (HR=2.0; 1 point). A final three-tiered prognostic model for thrombosis prediction was developed as low (score 0), intermediate (score 1 or 2) and high risk (score 3) (p<0.001). The hazard of thrombosis was 3.8% in low-risk group, 16.7% in the intermediate-risk group and 60% in the high-risk group (p<0.001). Patients with thrombotic complications during the follow-up had a significantly shorter survival (p=0.018). The new score based on CV risk factors and previous thrombotic events allows a better patient selection within prognostic-risk groups and improved identification of the high-risk patients for thrombosis.