BACKGROUND

The neutrophil-to-lymphocyte ratio (NLR) is the ratio between neutrophil and lymphocyte counts measured in peripheral blood. NLR is easily calculable based on a routine blood test available worldwide and may reflect systemic inflammation. However, the relationship between NLR and clinical outcomes in atrial fibrillation (AF) patients is not well-described.

METHODS

We calculated NLR at baseline in ENGAGE AF-TIMI 48, a randomized trial comparing edoxaban versus warfarin in patients with AF followed for 2.8 years (median). The association of baseline NLR with major bleeding events, major adverse cardiac events (MACE), cardiovascular death, stroke/systemic embolism, and all-cause mortality were calculated.

RESULTS

The median baseline NLR in 19,697 patients was 2.53 (interquartile range 1.89-3.41). NLR was associated with major bleeding events (HR 1.60; 95% CI 1.41-1.80), stroke/systemic embolism (HR 1.25; 95% CI, 1.09-1.44), MI (HR 1.73; 95% CI 1.41-2.12), MACE (HR 1.70; 95% CI 1.56-1.84), CV (HR 1.93; 95% CI 1.74-2.13) and all-cause mortality (HR 2.00; 95% CI 1.83-2.18). The relationships between NLR and outcomes remained significant after adjustment for risk factors. Edoxaban consistently reduced major bleeding. MACE, and CV death across NLR groups vs. warfarin.

CONCLUSIONS

NLR represents a widely available, simple, arithmetic calculation that could be immediately and automatically reported during a white blood cell differential measurement to identify patients with AF at increased risk of bleeding, CV events, and mortality.