A novel inflammatory-nutritional index: NPAR-correlates with the severity of type 2 diabetic foot ulcers

The neutrophil-percentage-to-albumin ratio (NPAR), an inflammatory-nutritional biomarker, has prognostic value in various diseases, but its relationship with DFU severity is unclear. This study investigates the association between NPAR and DFU severity.

This study was a retrospective cross-sectional study that analyzed clinical data from 1,221 consecutive hospitalized patients with type 2 diabetes mellitus (T2DM) foot lesions admitted to the Burn and Trauma Center of the First Affiliated Hospital of Wenzhou Medical University between January 2020 and January 2025. The severity of diabetic foot ulcers was graded using the Wagner classification system. Ordinal logistic regression, restricted cubic spline analysis, and subgroup analyses were applied to assess the association of NPAR with DFU severity.

Participants were stratified into NPAR quartiles: Q1 (≤17.89), Q2 (17.89-21.36), Q3 (21.36-25.81) and Q4 (≥25.82). Higher NPAR values paralleled greater Wagner grades, longer hospital stays, higher costs and more frequent surgical procedures. In the unadjusted model, each one-unit rise in NPAR conferred an odds ratio (OR) of 1.197 (95% CI, 1.170-1.225) for advanced DFU severity. After full adjustment for 17 covariates, the OR remained 1.174 (95% CI, 1.143-1.205, p < 0.001). Across quartiles, a pronounced dose-response relationship was observed: subjects in Q4 exhibited an 11.3-fold higher risk of severe DFU relative to Q1 (OR = 11.344; 95% CI, 7.621-16.886). RCS analysis revealed a non-linear threshold effect; the risk of worsening DFU escalated sharply once NPAR exceeded 21.4. Trend tests indicated a 2.214-fold incremental risk per quartile (P-for-trend < 0.001). Subgroup analyses confirmed the stability of these associations irrespective of sex, age, smoking, alcohol consumption or hypertension status.

NPAR is independently and robustly associated with DFU severity in a non-linear dose-dependent manner. As an inexpensive and readily obtainable inflammatory-nutritional composite index, NPAR may help assess the severity of DFU at presentation and assist in clinical decision-making, thereby supplementing clinical decision-making.