Preoperative neutrophil-to-lymphocyte ratio is associated with amputation level progression in patients with diabetic...

Amputation-level progression after below-knee amputation (BKA) is associated with functional and psychological burden in diabetic foot disease. We evaluated the association between preoperative neutrophil-to-lymphocyte ratio (NLR) and short-term progression from BKA to above-knee amputation (AKA).

This single-center retrospective cohort included 105 consecutive adults undergoing primary transtibial BKA for diabetic foot complications. The primary outcome was conversion from the index BKA to AKA within 3 months. Demographic, clinical, laboratory, disease severity, perioperative, and 12-Item Short Form Health Survey Version 1 (SF-12v1) data were obtained from medical records. A parsimonious multivariable logistic regression model including age, Wound, Ischemia, and foot Infection (WIfI) stage, Wagner grade, C-reactive protein (CRP), serum albumin, and NLR evaluated the adjusted association between NLR and amputation-level progression. Sensitivity analyses examined NLR estimate stability across alternative specifications. Receiver operating characteristic analysis explored the apparent discriminative ability of NLR.

Within 3 months, 53 of 105 patients (50.5%) progressed from BKA to AKA. Median preoperative NLR was higher among patients with progression than among those maintaining the initial BKA level [10.42 (interquartile range: 5.68-13.03) vs. 5.47 (3.24-9.04), p < 0.001]. Patients with progression also had higher neutrophil and lower lymphocyte counts (both p = 0.006). In the primary model, each one-unit increase in NLR was associated with 29% higher odds of progression (adjusted odds ratio: 1.29, 95% confidence interval: 1.14-1.47, p < 0.001). The association remained significant after excluding WIfI stage, CRP, Wagner grade, or both CRP and Wagner grade. Exploratory ROC analysis yielded an apparent area under the curve of 0.73. Postoperative SF-12v1 mental component scores, assessed approximately 3 weeks after BKA and before AKA conversion, were lower among patients with progression (p < 0.001).

Preoperative NLR was associated with early amputation-level progression after adjustment for available covariates. NLR may provide adjunctive information regarding systemic inflammatory burden but should not be interpreted as a validated standalone predictor or clinical decision threshold. These hypothesis-generating findings require confirmation in larger prospective multicenter cohorts with comprehensive vascular data and internal and external validation.