Neutrophil to Lymphocyte Ratio as a Predictor of Outcomes after Amputation

A systematic review of the neutrophil to lymphocyte and platelet to lymphocyte ratios in patients with lower extremity arterial disease

Lower extremity arterial disease (LEAD) is caused by atherosclerotic plaque in the arterial supply to the lower limbs. The neutrophil to lymphocyte and platelet to lymphocyte ratios (NLR, PLR) are established markers of systemic inflammation which are related to inferior outcomes in multiple clinical conditions, though remain poorly described in patients with LEAD. This review was carried out in accordance with PRISMA guidelines. The MEDLINE database was interrogated for relevant studies. Primary outcome was the prognostic effect of NLR and PLR on clinical outcomes following treatment, and secondary outcomes were the prognostic effect of NLR and PLR on disease severity and technical success following revascularisation. There were 34 studies included in the final review reporting outcomes on a total of 19870 patients. NLR was investigated in 21 studies, PLR was investigated in two studies, and both NLR & PLR were investigated in 11 studies. Relating to increased levels of systemic inflammation, 20 studies (100%) reported inferior clinical outcomes, 13 (92.9%) studies reported increased disease severity, and seven (87.5%) studies reported inferior technical results from revascularisation. The studies included in this review support the role of elevated NLR and PLR as key components influencing the clinical outcomes, severity, and success of treatment in patients with LEAD. The use of these easily accessible, cost effective and routinely available markers is supported by the present review.

A scoping review on nutritional intake and nutritional status in people with a major dysvascular lower limb amputation

PURPOSE

To systematically review literature on nutritional intake, nutritional status and nutritional interventions, and to study their association with short- and long-term clinical outcomes in people with a major dysvascular lower limb amputation.

METHODS

PubMed, Ovid, CINAHL, and The Cochrane Library were searched. Studies were included if nutritional intake, nutritional status, or nutritional interventions in people with a major dysvascular lower limb amputation were analyzed.

RESULTS

Of the 3038 unique papers identified, 30 studies were included. Methodological quality was moderate (1 study) or weak (29 studies). Limited information was available on nutritional intake (2 studies) and nutritional interventions (1 study). Nutritional intake and nutritional status were assessed by diverse methods. The percentage of people with a poor nutritional status ranged from 1% to 100%. In some studies, measures of poor nutritional status were associated with adverse short- and long-term clinical outcomes.

CONCLUSIONS

The percentage of people with a poor nutritional status is inconclusive in the major dysvascular lower limb amputation population, because of the heterogeneity of the assessment methods used. Some included studies reported a negative association between poor nutritional status and clinical outcomes. However, these results should be interpreted with caution, because of the limited quality of the studies available. Studies high in methodological quality and high in hierarchy of evidence are needed.IMPLICATIONS FOR REHABILITATIONThe proportion of people with a poor nutritional status in the major dysvascular lower limb amputation population is inconclusive.Poor nutritional status seems to affect clinical outcomes negatively.More uniformity in assessment of malnutrition in the major dysvascular lower limb amputation population is needed.

The Association of the Neutrophil-Lymphocyte Ratio With the Outcome of Diabetic Foot Ulcer

Introduction One of the most common lower-extremity impediments in people suffering from diabetes mellitus (DM) is foot ulceration. Neutrophil-lymphocyte ratio (NLR) is a useful measure in predicting disease-specific morbidity and mortality. Objectives The objective is to study the association between diabetic foot ulcer healing and the NLR. Methodology A prospective analytical study was conducted among 100 patients with diabetic foot ulcers admitted to a surgical ward in a teaching hospital between April and November 2022. Basic demographic details, ulcer examination, and NLR were evaluated on the day of admission, and the status of ulcers was assessed after six weeks and the outcome was compared with the NLR value. Data analysis was done using SPSS version 20 software (SPSS, Inc., Chicago, IL). Results The average neutrophils, lymphocytes, and neutrophil-lymphocyte ratio were, respectively, 94.73%, 14.97%, and 6.65%. 58% had healing ulcers, and 42% had non-healing ulcers. 44% of study subjects had NLR <6, which is normal, and 56% had NLR >6, which is abnormal. Among 58 subjects with healing ulcers, 75.9% had NLR < 6, and among 42 subjects with non-healing ulcers, 100% had NLR >6, which was statistically significant. The mean NLR in the healing group was 5.15 and in the non-healing group was 8.205; this was statistically significant. This shows an increased NLR has a predisposition towards non-healing chronic ulcers with a poor prognosis. Conclusion NLR can be used as a reliable indicator for determining the healing status of diabetic foot ulcers.

Preoperative HbA1c and Outcomes Following Lower Extremity Vascular Procedures

OBJECTIVES

Limited data exist evaluating pre-operative hemoglobin A1c (HbA1c) in patients undergoing vascular procedures for peripheral arterial disease (PAD). This study evaluated the relationship of preoperative HbA1c on outcomes after open and endovascular lower extremity (LE) vascular procedures for PAD.

METHODS

We selected patients with PAD admitted for elective LE procedures between September 2008 and December 2015 from the Cerner Health Facts® database using ICD-9-CM diagnosis and procedure codes. Bivariable analysis and multivariable logistic models examined the association of patient characteristics, procedure type, and preoperative HbA1c (normal < 6.5%, high ≥ 6.5%) with postsurgical outcomes that included infection, renal failure, respiratory or cardiac complications, length of stay (LOS), in-hospital mortality, and readmission.

RESULTS

Of 4,087 patients who underwent a LE vascular procedure for PAD, 2,462 (60.2%) had a preoperative HbA1c recorded. The cohort was mostly male (60%), white (73%), and underwent endovascular intervention (77%). Patients with high HbA1c levels were more likely of black race (p < .02) and had significantly higher comorbidities (p < .0001). Elevated HbA1c was associated with diabetes (p < .0001) and cellulitis (p = .05) on unadjusted analysis. Multivariable logistic regression (adjusting for patient, hospital, comorbidity and procedural characteristics) revealed that elevated HbA1c was significantly associated with 30-day readmission (OR = 1.06, 95% CI = 1.00-1.12), but was not associated with the other outcomes. An independent diagnosis of diabetes was not predictive of complications or readmission.

CONCLUSIONS

Historic glucose control, as evidenced by a high preoperative HbA1c level, is not associated with adverse outcome, other than readmission, in patients undergoing LE procedures for PAD. Given the known association of high perioperative glucose levels with poor outcome following vascular procedures, this is suggestive of a more important effect of perioperative, as opposed to chronic, glucose control upon outcome. Thus, we suggest focusing efforts on creating standardized goal-directed guidelines for glucose control in the perioperative period for LE vascular procedures to potentially mitigate complications.

An explainable machine learning model for predicting in-hospital amputation rate of patients with diabetic foot ulcer

Diabetic foot ulcer (DFU) is one of the most serious and alarming diabetic complications, which often leads to high amputation rates in diabetic patients. Machine learning is a part of the field of artificial intelligence, which can automatically learn models from data and better inform clinical decision‐making. We aimed to develop an accurate and explainable prediction model to estimate the risk of in‐hospital amputation in patients with DFU. A total of 618 hospitalised patients with DFU were included in this study. The patients were divided into non‐amputation, minor amputation or major amputation group. Light Gradient Boosting Machine (LightGBM) and 5‐fold cross‐validation tools were used to construct a multi‐class classification model to predict the three outcomes of interest. In addition, we used the SHapley Additive exPlanations (SHAP) algorithm to interpret the predictions of the model. Our area under the receiver‐operating‐characteristic curve (AUC) demonstrated a 0.90, 0.85 and 0.86 predictive ability for non‐amputation, minor amputation and major amputation outcomes, respectively. Taken together, our data demonstrated that the developed explainable machine learning model provided accurate estimates of the amputation rate in patients with DFU during hospitalisation. Besides, the model could inform individualised analyses of the patients' risk factors.

Preoperative lymphopaenia, mortality, and morbidity after elective surgery: systematic review and meta-analysis

BACKGROUND

In the general adult population, lymphopaenia is associated with an increased risk for hospitalisation with infection and infection-related death. The quality of evidence and strength of association between perioperative lymphopaenia across different surgical procedures and mortality/morbidity has not been examined by systematic review or meta-analysis.

METHODS

We searched MEDLINE, Embase, Web of Science, Google Scholar, and Cochrane databases from their inception to June 29, 2020 for observational studies reporting lymphocyte count and in-hospital mortality rate in adults. We defined preoperative lymphopaenia as a lymphocyte count 1.0-1.5×109 L-1. Meta-analysis was performed using either fixed or random effects models. Quality was assessed using the Newcastle-Ottawa Scale. The I2 index was used to quantify heterogeneity. The primary outcome was in-hospital mortality rate and mortality rate at 30 days.

RESULTS

Eight studies met the inclusion criteria for meta-analysis, comprising 4811 patients (age range, 46-91 yr; female, 20-79%). These studies examined preoperative lymphocyte count exclusively. Studies were of moderate to high quality overall, ranking >7 using the Newcastle-Ottawa Scale. Preoperative lymphopaenia was associated with a threefold increase in mortality rate (risk ratio [RR]=3.22; 95% confidence interval [CI], 2.19-4.72; P<0.01, I2=0%) and more frequent major postoperative complications (RR=1.33; 95% CI, 1.21-1.45; P<0.01, I2=6%), including cardiovascular morbidity (RR=1.77; 95% CI, 1.45-2.15; P<0.01, I2=0%), infections (RR=1.45; 95% CI, 1.19-1.76; P<0.01, I2=0%), and acute renal dysfunction (RR=2.66; 95% CI, 1.49-4.77; P<0.01, I2=1%).

CONCLUSION

Preoperative lymphopaenia is associated with death and complications more frequently, independent of the type of surgery.

PROSPERO REGISTRY NUMBER

CRD42020190702.

Blood Cell Count Biomarkers, Risk, and Outcomes of Ischemia-Related Lower Limb Amputations: Systematic Review

Lower limb amputations due to ischemia represent an important health care and social issue. However, there are currently no specific biomarkers able to predict the risk of amputation and postamputation complications and prognosis. We conducted a systematic review of studies investigating whether blood cell count indexes of systemic inflammation are linked to the risk and the outcome of lower limb amputations due to ischemia. Overall, in 22 studies involving 8832 patients selected for review, several blood cell count indexes, particularly the neutrophil lymphocyte ratio, showed some promise in terms of predicting amputations and general outcomes of conservative and surgical treatments, as well as postamputation complications and prognosis. However, largely due to methodological limitations, further prospective studies are required to establish the clinical utility and applicability of blood cell indexes in the routine management of patients with ischemia-related lower limb amputations.

Prognostic Significance of Preoperative Neutrophil-Lymphocyte Ratio in Vascular Surgery: Systematic Review and Meta-Analysis

OBJECTIVE

The global burden of surgical vascular disease is increasing and with it, the need for cost-effective, accessible prognostic biomarkers to aid optimization of peri-operative outcomes. The neutrophil-lymphocyte ratio (NLR) is emerging as a potential candidate biomarker for perioperative risk stratification. We therefore performed this systematic review and meta-analysis on the prognostic value of elevated preoperative NLR in vascular surgery.

METHODS

We searched Embase (Ovid), Medline (Ovid), and the Cochrane Library database from inception to June 2019. Screening was performed, and included all peer-reviewed original research studies reporting preoperative NLR in adult emergent and elective vascular surgical patients. Studies were assessed for bias and quality of evidence using a standardized tool. Meta-analysis was performed by general linear (mixed-effects) modelling where possible, and otherwise a narrative review was conducted. Between-study heterogeneity was estimated using the Chi-squared statistic and explored qualitatively.

RESULTS

Fourteen studies involving 5,652 patients were included. The overall methodological quality was good. Elevated preoperative NLR was associated with increased risk of long-term mortality (HR 1.40 [95%CI: 1.13-1.74], Chi-squared 60.3%, 7 studies, 3,637 people) and short-term mortality (OR: 3.08; 95%CI: 1.91-4.95), Chi-squared 66.59%, 4 studies, 945 people). Outcome measures used by fewer studies such as graft patency and amputation free survival were assessed via narrative review.

CONCLUSIONS

NLR is a promising, readily obtainable, prognostic biomarker for mortality outcomes following vascular surgery. Heterogeneity in patient factors, severity of vascular disease, and type of vascular surgery performed renders direct comparison of outcomes from the current literature challenging. This systematic review supports further investigation for NLR measurement in pre-vascular surgical risk stratification. In particular, the establishment of a universally accepted NLR cut-off value is of importance in real-world implementation of this biomarker.

Complex relationship between low albumin level and poor outcome after lower extremity procedures for peripheral artery disease

OBJECTIVE

A low albumin level has been associated with poor outcome, including death, in surgical patients. The mechanistic relationship, however, is more complex than simply nutritional. As studies are scant in the vascular population, we sought to examine the association of low albumin level with outcomes in patients undergoing open and endovascular lower extremity procedures for peripheral artery disease.

METHODS

Patients with peripheral artery disease undergoing lower extremity procedures (2008-2015) were selected from Cerner Health Facts database (Cerner Corporation, Kansas City, Mo) using International Classification of Diseases, Ninth Revision diagnosis and procedure codes. Age, sex, disease severity, and other comorbidities were captured. Outcomes were identified using codes and encounter data. A χ²analysis and multivariable logistic regression were performed.

RESULTS

There were 6170 patients evaluated; 4562 (74%) underwent endovascular procedures and 1608 (26%) underwent open surgery. Low albumin level (<3.5 g/dL) was associated with age ≥80 years (23.1% vs 16.3% normal; P < .0001), black race (21% vs 11.6% normal; P < .0001), tissue loss (38% vs 16.4% normal; P < .0001), and higher Charlson index (mean, 3.1 vs 2.2 in the normal group; P < .0001). Low albumin level was also associated with longer length of stay (4.9 vs 2.2 days normal; P < .0001), higher in-hospital mortality (1.9% vs 0.3% normal; P < .0001), and higher 30-day readmission (15% vs 12.7% normal; P = .02). Multivariable analysis demonstrated that low albumin level was strongly associated with in-hospital death (odds ratio [OR], 5.23; 95% confidence interval [CI], 2.00-13.70), infection (OR, 2.51; 95% CI, 1.96-3.22), renal failure (OR, 2.61; 95% CI, 1.79-3.79), and cardiac complications (OR, 2.59; 95% CI, 1.69-3.96). After multivariable adjustment, there was no association between albumin level and 30-day readmission.

CONCLUSIONS

Low preoperative albumin levels are associated with in-hospital death, prolonged length of stay, and severe morbidity after open and endovascular lower extremity procedures. As the majority of lower extremity procedures are elective, serious consideration should be given to deferring elective procedures until albumin levels have been optimized. Because of the pleiotropic effects of albumin, including antiplatelet and inflammatory function, study of this complex relationship may offer insights into how best to integrate this novel biomarker into vascular surgery decision-making.

Neutrophil-lymphocyte ratio predicts disease severity and outcome after lower extremity procedures

OBJECTIVE

Neutrophil-lymphocyte ratio (NLR) has been associated with inferior outcomes after lower extremity interventions. NLR has been associated with systemic inflammation and atherosclerotic burden. We examined NLR, severity of peripheral artery disease (PAD), and outcomes after endovascular or open surgical procedures.

METHODS

Inpatients undergoing lower extremity procedures (2008-2016) were selected from Cerner Health Facts database (Cerner Corporation, North Kansas City, Mo) using International Classification of Diseases, Ninth Revision procedure codes. Disease severity was grouped into claudication, rest pain, and tissue loss. Outcomes were identified using International Classification of Diseases, Ninth Revision codes. NLR was calculated preoperatively and postoperatively. A χ² analysis and multivariable logistic regression were performed. A receiver operating characteristic curve analysis was used to determine the cutoff for preoperative (low, <3.65; high, ≥3.65) and postoperative (low, <5.96; high, ≥5.96) NLR values.

RESULTS

There were 3687 patients evaluated; 2183 (59%) underwent endovascular procedures and 1504 (41%) had open procedures. Compared with black patients, claudication was more frequent in white patients (81.7% vs 72.7%; P < .0001), and tissue loss was less common (12.9% vs 20.9%; P < .0001). NLR values were higher for patients with tissue loss than for patients with rest pain or claudication (4.89, 4.33, and 3.11, respectively; P < .0001). Open procedures were associated with higher postoperative NLR values than endovascular procedures (6.8 vs 5.2; P < .0001). Mean preoperative and postoperative NLR values were greater in patients with more severe PAD. Multivariable analysis demonstrated that preoperative high NLR was strongly associated with in-hospital death (odds ratio [OR], 5.4; 95% confidence interval [CI], 1.68-17.07), cardiac complications (OR, 2.9; 95% CI, 1.57-5.40), amputation (OR, 2.5; 95% CI, 1.65-3.87), renal failure (OR, 1.9; 95% CI, 1.18-2.93), respiratory complications (OR, 1.7; 95% CI, 1.09-2.76), and prolonged length of stay (OR, 1.9; 95% CI, 1.89-3.71).

CONCLUSIONS

Preoperative and postoperative NLR significantly increases with disease severity for PAD, providing further evidence of NLR as a biomarker of a patient's systemic inflammatory state. After adjustment for confounders, NLR still remained strongly associated with death and other adverse outcomes after intervention for PAD. Further study of the clinical association of NLR with other vascular disorders, such as symptomatic carotid stenosis and symptomatic and ruptured aortic aneurysmal disease, is planned to guide individualized treatment to prevent stroke or aneurysm rupture.

Fibrinogen, Neutrophil-to-Lymphocyte Rate and Platelet-to-Neutrophil Rate as Novel Acute Phase Indicators in Patients with Thromboangiitis Obliterans

BACKGROUND/OBJECTIVES

The acute exacerbations and progressive deterioration seen in thromboangiitis obliterans (TAO) have been related to poor clinical outcomes. Here, we have studied the association of laboratory biomarkers with the acute phase of TAO (AP-TAO).

METHODS/RESULTS

We conducted a retrospective case-control study on 112 patients with TAO and 98 healthy controls; comparing the neutrophil-to-lymphocyte rate (NLR), lymphocyte-to-monocyte rate (LMR), platelet-to-neutrophil rate (PNR), fibrinogen (FIB), and apolipoprotein A-I (ApoA-I). Significantly higher NLR level, as well as lower LMR, PNR, and ApoA-I levels were observed in patients with TAO, particularly the acute phase. Significantly increased FIB was only observed in AP-TAO. A positive correlation was found between NLR and with C-reactive protein (CRP) in the acute phase (r = 0.817, P < 0.001). Moreover, NLR, PNR, and FIB levels of 3.38, 45.12, and 3.69 were shown to be the predictive cut-off values for the AP-TAO (sensitivity 72.5, 82,4, and 66,7%, specificity 92.2, 78.4, and 96.1%; area under the curve [AUC] 0.875, 0.855, and 0.872), respectively. The FIB level was independently associated with the AP-TAO (OR = 11.420, P = 0.007).

CONCLUSIONS

NLR, PNR, and FIB may be useful markers for the identification of inflammation and the AP-TAO. FIB may be an independent risk factor for the acute phase.