Neutrophil‐to‐lymphocyte ratio (NLR) at diagnosis in essential thrombocythemia: A new promising predictor of thrombotic events

ABSTRACT Background Myeloproliferative neoplasms represent a heterogeneous group of acquired hematopoietic stem cell diseases in which chronic inflammation is essential for both clonal evolution and thrombotic complications. The neutrophil‐to‐lymphocyte ratio (NLR), reflecting the imbalance between systemic inflammation and immunity, is emerging as a prognostic biomarker in several diseases, including hematological ones. Methods A total of 473 patients with essential thrombocythemia (ET), the relationship between NLR value at diagnosis and the risk of thrombotic events in the follow‐up, in addition to conventional clinical and biological variables, were retrospectively analyzed. Results A total of 78 thrombotic events were reported for an incidence rate of 1.8 × 100 patients/year. In multivariate analysis, NLR value ≥4 at diagnosis was associated with higher cumulative thrombotic risk (hazard ratio [HR], 2.05; 95% CI, 1.29–2.28; p = .0001) as well International Prognostic Score for Thrombosis in Essential Thrombosis score intermediate‐high (HR, 2.69; 95% CI, 1.27–5.72; p = .01) and diabetes (HR, 2.49; 95% CI, 1.23–3.05; p = .010). Concerning arterial thrombotic events, in multivariate analysis, NLR value at diagnosis ≥4 was predictive for thrombosis (HR, 2.13; 95% CI, 1.31–4.04; p = .001 as well diabetes (HR, 2.44; 95% CI, 1.05–5.68; p = .04) and hypertension (HR, 2.46; 95% CI, 1.05–5.68; p = .01). About venous thrombotic events, NLR value ≥5 was a marker predictive for venous thrombosis (HR, 2.99; 95% CI, 2.45–6.48; p = .01) as well age >60 years old (HR, 2.26; 95% CI, 1.0–5.10; p = .05). Conclusion NLR value is a simple, cost‐effective, and easy‐to‐obtain inflammatory marker that can predict a diagnosis the risk of thrombosis in ET. Our results suggest that NLR value could be integrated into conventional cardiovascular risk scores, to better classify high‐risk patients who are candidates for cytoreductive therapy. Further larger and prospective studies are warranted.