Neutrophil to Lymphocyte Ratio as a Predictor of Outcomes after Amputation.

BACKGROUND

The neutrophil-to-lymphocyte ratio (NLR) has become a prognostic marker for proinflammatory states. It is associated with outcomes in many clinical processes including critical limb ischemia. We sought to identify predictors of amputation failure and mortality, in addition to the role of NLR in patients undergoing above-knee amputations (AKAs) or below-knee amputations (BKAs).

METHODS

All patients undergoing BKA or AKA between 2004 and 2014 at 3 institutions were identified and analyzed (n = 513). Patients were excluded if they did not have a complete blood count with differential within 7 days prior to their operations. Comparison groups were formed between patients requiring unplanned revision and those who did not, and additionally between survivors and nonsurvivors at 30 days postamputation. Patient demographics, intraoperative data, and postoperative courses were compared. A multinomial logistic regression model was created to further compare the groups.

RESULTS

Four hundred and ten patients were included for analysis, of which 142 (35%) required unplanned revision. Nearly 5% of patients (19/410) died within 30 days of the initial amputation. On univariate analysis, those requiring revision were more likely to be current smokers compared to former smokers (P = 0.004 and P = 0.021, respectively), have a lower ankle-brachial index (ABI) (P = 0.019), and have undergone a BKA (P < 0.001). Patients with congestive heart failure (CHF) were less likely to require a revision after an amputation (P = 0.007). Postoperative NLR was higher in patients requiring revision (9.9 vs. 7.0, P < 0.001) and both preoperative and postoperative NLRs were higher in those with 30-day mortality (21.0 vs. 7.0, P < 0.001; 19.4 vs. 7.5, P < 0.001). A multinomial logistic regression model identified CHF (P = 0.004), ABI (P = 0.041), and elevated body mass index (BMI, P = 0.045) as predictors of revision, while coronary artery disease (CAD, P = 0.031), CHF (P = 0.029), and postoperative NLR (P < 0.001) were predictive of 30-day mortality.

CONCLUSIONS

Postoperative elevated NLR, CAD, and CHF are predictors of 30-day mortality in patients undergoing major limb amputation, while CHF, elevated ABI, and high BMI are predictors of revision. This study suggests that NLR may have a role as a biomarker for poor outcomes in patients with underlying peripheral vascular disease and warrants further investigation.