Abstract
Thromboembolic events (TE) represent the commonest cause of morbidity and mortality in polycythemia vera (PV) and essential thrombocythaemia (ET). The QRISK3 model is a tool for predicting TE in the general population, with 7.5% recognised as a threshold to identify high-risk patients. We analyzed data of 937 patients (490 ET and 447 PV) with a median follow-up of 85 and 95 months, reporting an occurrence of 52 and 73 TE, respectively. Median QRISK3 scores at diagnosis were higher in conventional high-risk patients in both cohorts (ET; 4.2 in high-risk vs. 2.4 in low-risk, PV; 8.8 vs. 2.8, p < 0.001). During follow-up, a QRISK3 score greater than 7.5%, demonstrated potential to further stratify individuals at high risk of TE, outperforming standard risk assessments in both low and high-risk patients. Using cytoreductive treatment instead of active surveillance in patients with QRISK3 ≥ 7.5% conferred a reduced risk of thrombosis in both cohorts. Of this group, 79.7% with ET and 86.9% with PV, on cytoreductive therapy, remained thrombosis free, compared with 64.1% and 57.1% of those not receiving cytoreductive therapy (p = 0.018/0.034). QRISK3 identifies patients in whom cytoreductive therapies may be indicated, and provides a tool that allows patients to assess, monitor and reduce their cardiovascular risk.