Association of the neutrophil-to-lymphocyte ratio with sudden cardiac death in the patients with diabetic foot ulcer.

Aims: This study aims to investigate the relationship between the neutrophil-to-lymphocyte (NLR) and the risk of sudden cardiac death (SCD) in the patients with diabetic foot ulcer (DFU). Methods: A retrospective study enrolled 688 patients with DFU who were admitted to Air Force Medical Center between January 2010 and December 2023. To control for potential confounding effects, a 1:1 propensity score matching (PSM) method was applied. The relationship between NLR and SCD risk was analyzed using the Kaplan-Meier (K-M) survival curve analysis, multivariate Cox proportional hazard regression model, Restricted cubic spline (RCS) model analysis and subgroup analyses. Results: Over a median follow-up period of 61 months, 38 cases of SCD were documented. Based on median NLR, participants were stratified into higher (<4.22) and lower (≥4.22) NLR groups. Cox proportional hazard model revealed that individuals with higher NLR was independently associated with the increased risk of SCD (HR: 3.64, 95% CI: 1.21 ~ 10.91, P=0.021). RCS model showed that SCD risk was non-linearly correlated with gradual increases in NLR levels. Subgroup analyses confirmed the stability of the results. Conclusions: Elevated NLR independently confers an increased risk for SCD in individuals with DFU.