Preoperative White Blood Cell Count is Independently Associated With Higher Perioperative Cardiac Enzyme Release and Increased 1-Year Mortality After Coronary Artery Bypass Grafting

Risk factors of major lower limb amputation in symptomatic peripheral artery disease: a retrospective cohort study

AIM

To find risk factors of major amputation in patients with peripheral artery disease (PAD) by a combination of both personal risk factors and treatment.

METHODS

This was a retrospective cohort study enrolled adult patients diagnosed as symptomatic PAD. Predictors for major amputation were analyzed.

RESULTS

There were 221 patients with PAD met the study criteria; 28 patients (12.67%) had major amputation events. There were three independent factors Rutherford classification, white blood cell, and serum albumin. The adjusted odds ratio (95% confidence interval) of these factors were 1.824 (1.118, 2.976), 1.073 (1.019, 1.131), and 0.421 (0.202, 0.879), respectively.

CONCLUSIONS

Serum albumin was modifiable to prevent future major amputation in patients with PAD.

Machine Learning Models With Prognostic Implications for Predicting Gastrointestinal Bleeding After Coronary Artery Bypass Grafting and Guiding Personalized Medicine: Multicenter Cohort Study

BACKGROUND

Gastrointestinal bleeding is a serious adverse event of coronary artery bypass grafting and lacks tailored risk assessment tools for personalized prevention.

OBJECTIVE

This study aims to develop and validate predictive models to assess the risk of gastrointestinal bleeding after coronary artery bypass grafting (GIBCG) and to guide personalized prevention.

METHODS

Participants were recruited from 4 medical centers, including a prospective cohort and the Medical Information Mart for Intensive Care IV (MIMIC-IV) database. From an initial cohort of 18,938 patients, 16,440 were included in the final analysis after applying the exclusion criteria. Thirty combinations of machine learning algorithms were compared, and the optimal model was selected based on integrated performance metrics, including the area under the receiver operating characteristic curve (AUROC) and the Brier score. This model was then developed into a web-based risk prediction calculator. The Shapley Additive Explanations method was used to provide both global and local explanations for the predictions.

RESULTS

The model was developed using data from 3 centers and a prospective cohort (n=13,399) and validated on the Drum Tower cohort (n=2745) and the MIMIC cohort (n=296). The optimal model, based on 15 easily accessible admission features, demonstrated an AUROC of 0.8482 (95% CI 0.8328-0.8618) in the derivation cohort. In external validation, the AUROC was 0.8513 (95% CI 0.8221-0.8782) for the Drum Tower cohort and 0.7811 (95% CI 0.7275-0.8343) for the MIMIC cohort. The analysis indicated that high-risk patients identified by the model had a significantly increased mortality risk (odds ratio 2.98, 95% CI 1.784-4.978; P<.001). For these high-risk populations, preoperative use of proton pump inhibitors was an independent protective factor against the occurrence of GIBCG. By contrast, dual antiplatelet therapy and oral anticoagulants were identified as independent risk factors. However, in low-risk populations, the use of proton pump inhibitors (χ21=0.13, P=.72), dual antiplatelet therapy (χ21=0.38, P=.54), and oral anticoagulants (χ21=0.15, P=.69) were not significantly associated with the occurrence of GIBCG.

CONCLUSIONS

Our machine learning model accurately identified patients at high risk of GIBCG, who had a poor prognosis. This approach can aid in early risk stratification and personalized prevention.

TRIAL REGISTRATION

Chinese Clinical Registry Center ChiCTR2400086050; http://www.chictr.org.cn/showproj.html?proj=226129.

Predicting Mortality Following Odontoid Fracture Fixation in Elderly Patients: CAADS-16 Score

STUDY DESIGN

Retrospective Review of a National Database.

INTRODUCTION

By utilizing a national database, this study aims to quantify the predictors of 30-day mortality after odontoid fixation and guide appropriate management for patients in whom the choice between operative and non-operative management is unclear.

METHODS

The American College of Surgeons National Surgical Quality Improvement Database was queried using Current Procedural Terminology (CPT) codes and International Classification of Disease (ICD) codes to identify patients 60 or older who underwent surgical fixation of an odontoid fracture from 2005 to 2020. Risk factors for mortality significant in univariate and subsequent multivariate analysis were used to develop a scoring system to predict post-operative mortality.

RESULTS

608 patients were identified. Patients were split into a non-mortality 30 days post-op group, and into a mortality 30 days post-op group. The following risk factors were included in the scoring system: functional dependency, disseminated cancer, albumin less than 3.5, WBC count greater than 16 k, anterior surgical approach, and pre-op SIRS. Using a cutoff value of 2, the CAAD-16 score had a sensitivity and specificity of 82% and 81%, respectively. The ASA score, cutoff at 4, showed a sensitivity and specificity of 64% and 75% respectively.

CONCLUSIONS

This sample of 294 patients represents one of the largest samples of odontoid fracture fixation patients available in the literature and comes from a nationally representative database. We structure relevant risk factors into the CAADS-16 score, which has the potential to be a clinically relevant tool to prevent short-term postoperative mortality.

The Prognostic Significance of Leukocyte Count on All-Cause and Cardiovascular Disease Mortality: A Systematic Review and Meta-Analysis

White blood cells (WBCs) act as mediators of inflammatory responses and are commonly measured in hospitals. Although several studies have reported a relation between WBC count and mortality, no systematic review or meta-analysis has been conducted. This study aimed to identify an association between WBC count and mortality. We conducted a systematic search on Embase using keywords such as "white blood cell" and "mortality." We analyzed the hazard ratios (HRs) for WBC count of 1.0 × 109 cells/L regarding 2 criteria: the cause of mortality and the follow-up period. A total of 13 of 222 articles comprising a total of 62,904 participants were included in this study, meeting the criteria set. A positive association was observed between WBC count and mortality, as indicated by an HR of 1.10 (95% confidence interval [CI] 1.08 to 1.13). In additionally, WBC count emerged as a significant predictor of mortality in both groups, with an HR of 1.10 (95% CI 1.07 to 1.12) for patients with cardiovascular disease and an HR of 1.12 (95% CI 1.07 to 1.17) for the general population or patients with COVID-19. Furthermore, a higher WBC count demonstrated a significant association with long-term all-cause mortality (HR 1.09, 95% CI 1.07 to 1.12) and long-term cardiovascular mortality (HR 1.05, 95% CI 1.02 to 1.07). Similarly, a significant association was found between higher WBC count and short-term all-cause mortality (HR 1.12, 95% CI 1.09 to 1.16) and cardiovascular mortality (HR 1.12, 95% CI 1.07 to 1.17). Further research is necessary to explore the relation between WBC count and disease progression or death and to establish causality between elevated WBC count and disease progression.

WBC count predicts heart failure in diabetes and coronary artery disease patients: a retrospective cohort study

Aims

White blood cell (WBC) count in healthy people is associated with the risk of coronary artery disease (CAD) and mortality. This study aimed to determine whether WBC count predicts heart failure (HF) requiring hospitalization as well as all‐cause death, acute myocardial infarction (AMI) and stroke in patients with Type 2 diabetes mellitus and established CAD.

Methods

We conducted this retrospective registry study that enrolled consecutive patients with Type 2 diabetes mellitus and CAD based on coronary arteriography records and medical charts at 70 teaching hospitals in Japan from 2005 to 2015. A total of 7608 participants (28.2% women, mean age 68 ± 10 years) were eligible. In the cohort, the median (interquartile range) and mean follow‐up durations were 39 (16.5–66.1 months) and 44.3 ± 32.7 months, respectively. The primary outcome was HF requiring hospitalization. The secondary outcomes were AMI, stroke, all‐cause death, 3‐point major adverse cardiovascular events (MACE) (AMI/stroke/death) and 4‐point MACE (AMI/stroke/death/HF requiring hospitalization). Outcomes were reported as cumulative incidences (proportion of patients experiencing an event) and incidence rates (events/100 person‐years). The primary and secondary outcomes were assessed using the Kaplan–Meier method and were compared using the log‐rank test stratified by the baseline WBC count. The association between the WBC count at baseline and each MACE was assessed using the Cox proportional hazard model and expressed as the hazard ratio (HR) and 95% confidence interval (CI) after adjusting for other well‐known risk factors for MACE.

Results

During the follow‐up, 880 patients were hospitalized owing to HF. The WBC Quartile 4 (≥7700 cells/μL) had significantly lower HF event‐free survival rate (log‐rank test, P < 0.001). The HRs for HF events requiring hospitalization with each WBC quartile compared with the lowest in the first WBC quartile were 1 for Quartile 1 (WBC < 5300 cells/μL), 1.20 (95% CI, 0.96–1.5; P = 0.1) for Quartile 2 (5300 ≤ WBC < 6400), 1.34 (95% CI, 1.08–1.67; P = 0.009) for Quartile 3 (6400 ≤ WBC < 7700) and 1.62 (95% CI, 1.31–2.00; P < 0.001) for Quartile 4 after adjusting for covariates. Similar findings were observed for the risk of AMI and death; however, no significant difference was found for stroke. WBC Quartile 4 patients had a significantly lower 3‐ or 4‐point MACE‐free survival rate (log‐rank test, P < 0.0001).

Conclusions

A higher WBC count is a predictor of hospitalization for HF, all‐cause death and AMI but not for stroke in patients with concurrent Type 2 diabetes mellitus and established CAD.

Preoperative Neutrophil and Lymphocyte Ratio as a Predictor of Mortality and Morbidity After Cardiac Surgery

BACKGROUND

Inflammatory markers, such as neutrophils and lymphocytes, for risk stratification of postoperative morbidity and mortality in patients with cardiovascular disease may provide benefit for patient selection for cardiac surgery. This study aimed to investigate the association between preoperative neutrophil to leucocyte ratio (NLR) after cardiac surgery.

METHODS

A retrospective study from September 2014 to November 2017 undergoing cardiac surgery at Waikato Hospital was conducted. Preoperative haematological profiles, patient factors and primary and secondary endpoints were obtained. The primary endpoint was 30-day new postoperative atrial fibrillation requiring treatment, new neurological insult, readmission within 30 days and 30-day mortality. The secondary endpoint was long-term all cause mortality.

RESULTS

Of the 1,694 patients included in the study, 21% (356/1,694) of patients had new atrial fibrillation (AF), 3.0% (51/1,694) strokes, 10.6% (180/1,694) readmissions and 2.8% (47/1,694) deaths within 30 days were observed. Receiver operator curve (ROC) returned a cut-off value of NLR equal to or greater than 3.23 (high NLR) to be associated with greatest mortality. Subsequently, a high NLR was compared to the endpoints. High NLR was associated with higher postoperative (p<0.001) and discharge creatinine, longer ICU stay (p=0.012), prolonged intubation and ventilation (p<0.001), new neurological status (p=0.002) and increased risk of returning to theatre (p=0.009). After logistic regression, high NLR was associated with increased mortality (OR 3.36, p=0.001).

CONCLUSIONS

The interpretation and utilisation of readily available haematological markers can provide further risk stratification data to the surgeon when considering the postoperative cardiac surgery risks.

Effects of Preoperative WBC Count on Post-CABG Surgery Clinical Outcome

OBJECTIVE

White blood cells (WBCs) play a major role in inflammation, with effects on the vascular wall, the microvascular blood flow, and endothelial cells and endothelial function. Previous studies have shown that a high WBC count may increase the risk of cardiovascular complication rate and mortality after coronary artery bypass graft (CABG) surgery. The aim of the study was to evaluate the association between preoperative WBC count and the post-CABG clinical outcome.

METHODS

A retrospective study that was based on 239 patients who underwent CABG surgery in our medical center. Statistical analysis estimated the effect of WBC count in postoperative clinical outcomes, including atrial fibrillation, length of stay, readmission rate, and death.

RESULTS

The preoperative WBC count was associated with longer hospitalization length (B = 0.392, P < 0.01). A preoperative WBC count >8150/μL predicted a longer stay (Z = 2.090, P = 0.03). A low lymphocyte count was associated with atrial fibrillation (B = -0.543, P = 0.03). Female patients were older (Z = 2.920, P < 0.01), had impaired renal function (Z = -3.340, P < 0.01), and had a higher rate of postoperative atrial fibrillation (df 2 = 3.780, P = 0.05) and readmission (df 2 = 5.320, P = 0.02).

CONCLUSIONS

Preoperative WBC count may have an effect on the postoperative clinical outcome in patients undergoing CABG. Surgeons should pay more attention to patients' WBC count and sex and plan surgery and postoperative management accordingly.

Stability across time of the neutrophil-lymphocyte and lymphocyte-neutrophil ratios and associations with outcomes in cardiac surgery patients

Background

Elevated white blood cell counts and leukocyte ratios are recognized markers of systemic inflammation associated with poor surgical outcomes. We analyzed the temporal stability and prognostic value of the preoperative Neutrophil-to-Lymphocyte ratio (NLR) and Lymphocyte-to-Neutrophil ratio (LNR) in patients undergoing coronary artery bypass grafts and/or valve surgery.

Methods

We retrospectively reviewed 558 patients who underwent elective cardiac surgery between July 2014 and December 2016, excluding patients with immunosuppressed status. The stability of NLR and LNR was evaluated using interclass correlation coefficients. The patients were dichotomized into two groups, high NLR and low NLR, based on the median value of preoperative NLR in our cohort. A logistic regression model compared preoperative NLR and LNR values to clinical outcomes, including a composite of perioperative events and mid-term mortality.

Results

We identified that NLR reliability over time was good (ICC = .592; R-squared = .351), and LNR reliability over time was excellent (ICC = .761; R-squared = .601). Furthermore, an increased duration between collection dates was not significantly correlated with increased variability in NLR (Pearson Correlation Coefficient: −.111, p = .117). On multivariate model, neither high NLR (OR = .879, p = .168) nor low LNR (OR = 3.30, p = .214) was significantly associated with a composite of perioperative events, but increased LNR was associated with lower mid-term mortality (HR .001, p = .026).

Conclusions

Both NLR and LNR were stable over time, up to 100 days, but LNR values were more consistent compared to NLR. High LNR was significantly associated with decreased risk of mid-term mortality, and LNR showed a stronger relationship with mid-term mortality than its NLR counterpart. Both of these findings indicate that LNR may be a more useful and valuable clinical marker.

WBC Associates with Readmission Following Cystectomy

Background: Radical cystectomy is associated with perioperative complication rates exceeding 50% in some series. Readmission rates are increasingly used as a surgical quality metric. White blood cell count is a crude surrogate for physiologic processes which may reflect postoperative complications leading to readmission. Objective: We assessed the association between final white blood cell count at discharge and risk of readmission following radical cystectomy. Methods: Records on 477 patients undergoing radical cystectomy from 2006-2013 were reviewed. Final white blood cell count was defined as the last documented value during index admission. Univariate analysis was performed using Fisher's exact, Wilcoxon rank sum test, and Spearman's coefficient tests where appropriate. Multivariable logistic regression models were used to test the associations between final white blood cell count and readmission. Results: 34% of patients were readmitted within 90 days of surgery. Amongst this cohort, a cutoff final white blood cell count of 9000/mm³ was identified, with a significantly higher proportion of patients with values >9000/mm³ experiencing readmission than those with values≤9000/mm³ (42% vs 28%, p = 0.004). Other perioperative variables associated with an increased readmission rate included initial hospital length of stay≤10 days, and receipt of a continent diversion. Following adjustment, final white blood cell count >9000/mm³ was associated with increased risk of readmission (OR 2.09, 95% CI 1.23-3.53, p = 0.006). Conclusions: Final white blood cell count is associated with hospital readmission following radical cystectomy. This metric may provide important guidance in discharge algorithms.

Perioperative neutrophil to lymphocyte ratio as a predictor of poor cardiac surgery patient outcomes

Purpose

The purpose of the present study was to investigate the association between the perioperative neutrophil to lymphocyte ratio (NLR) and cardiac surgery patient outcomes.

Patients and methods

A retrospective cohort study of 145 patients who underwent cardiac surgery in a tertiary hospital of Athens, Greece, from January to March 2015, was conducted. By using a structured short questionnaire, this study reviewed the electronic hospital database and the medical and nursing patient records for data collection purposes. The statistical significance was two-tailed, and p-values <0.05 were considered significant. The statistical analysis was performed with Mann–Whitney U test and Spearman’s correlation coefficient, by using the Statistical Package for Social Sciences software (IBM SPSS 21.0 for Windows).

Results

The increased preoperative levels of NLR were associated with significantly higher mortality, both in-hospital (p=0.001) and 30-day (p=0.002), prolonged postoperative hospital length of stay (LOS), both in the cardiac intensive care unit (ICU) (p=0.002), and in-hospital (p=0.018), and likewise with delayed tracheal extubation (p≤0.001). Furthermore, patients with elevated NLR during the second postoperative day had significantly higher in-hospital mortality (p=0.018), increased incidence of pneumonia (p=0.022), higher probability of readmission to the ICU (p=0.002), prolonged ICU LOS (p≤0.001), and delayed tracheal extubation (p≤0.001).

Conclusion

Increased perioperative NLR seems to be associated with significantly higher mortality and morbidity in cardiac surgery patients. At the same time, NLR is a significant and inexpensive biomarker for the early identification of patients at high risk for complications. In addition, NLR levels could lead clinicians to perform measures for the optimal therapeutic patient approach.

Association Between the Neutrophil/Lymphocyte Ratio and Acute Kidney Injury After Cardiovascular Surgery: A Retrospective Observational Study

A high neutrophil-lymphocyte ratio (N/L ratio) was associated with the development of acute kidney injury (AKI) in patients with severe sepsis. We sought to investigate the association between the perioperative N/L ratios and postoperative AKI in patients undergoing high-risk cardiovascular surgery.A retrospective medical chart review was performed of 590 patients who underwent cardiovascular surgeries, including coronary artery bypass, valve replacement, patch closure for atrial or ventricular septal defect and surgery on the thoracic aorta with cardiopulmonary bypass (CPB). Baseline perioperative clinical parameters, including N/L ratios measured before surgery, immediately after surgery, and on postoperative day (POD) one were obtained. Multivariate logistic regression analysis was used to evaluate risk factors.A total of 166 patients (28.1%) developed AKI defined by the KDIGO (kidney disease improving global outcomes) criteria in the first 7 PODs. Independent risk factors for AKI included old age, decreased left ventricular systolic function, preoperative high serum creatinine, low serum albumin and high uric acid levels, intraoperative large transfusion amount, oliguria, hyperglycemia, and elevated N/L ratio measured immediately after surgery and on POD one. The quartiles of immediately postoperative N/L ratio were associated with graded increase in risk of AKI development (fourth quartile [N/L ratio≥10] multivariate odds ratio 5.90, 95% confidence interval [CI] 2.74-12.73; P < 0.001), a longer hospital stay, and a higher in-hospital and 1-year mortality rate (fourth quartile [N/L ratio≥10] adjusted hazard ratio for 1-year mortality [8.40, 95% CI 2.50-28.17]; P < 0.001).In patients undergoing cardiovascular surgery with CPB, elevated N/L ratios in the immediately postoperative period and on POD one were associated with an increased risk of postoperative AKI and 1-year mortality. The N/L ratio, which is easily calculable from routine work-up, can therefore assist with risk stratification of AKI and mortality in high-risk surgical patients.

L-Carnitine Supplementation Reduces Short-Term Neutrophil-Lymphocyte Ratio in Patients Undergoing Coronary Artery Bypass Grafting

This study aims to investigate whether preoperative L-carnitine supplementation affects the neutrophil-to-lymphocyte ratio (NLR) in patients undergoing coronary artery bypass grafting surgery. The neutrophil-to-lymphocyte ratio is an inflammatory marker that has proven usefulness for predicting postoperative complications in coronary artery bypass surgery. A lot of studies concerning the role of L-carnitine in the immune system have been performed, contradictory results have been reported on its effects on absolute numbers of WBC subtypes. This randomized, double-blinded, placebo-controlled study was conducted among patients scheduled for coronary artery bypass grafting surgery between June 2012 and December 2013 in our cardiovascular surgery clinic. A total of 60 consecutive patients were randomized and divided into 2 groups. The first group received 2 g of L-carnitine in 1000 mL of 0.9% saline solution infused over 24 hours for each of the 3 preoperative days (L-carnitine group, n = 30), or only 1000 mL of 0.9% saline solution for the same time period (placebo group, n = 30). The basal values of leukocyte, neutrophil, lymphocyte counts, and neutrophil to lymphocyte ratio were similar in the 2 groups. After L-carnitine supplementation (just before surgery), leukocyte and neutrophil counts of the L-carnitine group were significantly lower than those of the placebo group (7.7 ± 1.5 versus 9.7 ± 2.6, P < 0.001 and 4.6 ± 1.3 versus 6.5 ± 2.2, P < 0.001). On postoperative day 1, lymphocyte counts were significantly higher in the L-carnitine group (1.1 ± 0.6 versus 0.8 ± 0.9, P < 0.001). Moreover, the increase in NLR was significantly lower in the L-carnitine group at postoperative day 1 (20.7 ± 13.8 versus 10.8 ± 4.1, P < 0.001). Preoperative L-carnitine supplementation may reduce neutrophil-lymphocyte ratio during the early postoperative period of coronary artery bypass grafting surgery.

Comparing the effectiveness of neutrophil-lymphocyte ratio as a mortality predictor on middle and advanced age coronary artery bypass graft patients

OBJECTIVE

In this study, the effect of neutrophil-lymphocyte ratio (NLR), which is a recently developed inflammatory parameter, as an early stage mortality predictive marker on coronary artery bypass (CABG) patients of various age groups was examined.

METHODS

Seventy eight patients under the age of 45 (Group 1) and 80 patients who were older than 45 (Group 2) randomly chosen from the patients who underwent isolated CABG surgery, were examined. The preoperative characteristics and NLRs were noted. The primary end point of the study was determined as all-cause in- hospital mortality.

RESULTS

Mortality was observed in 2 patients in Group 1 and 11 patients in Group 2. The threshold value of NLR was 2,47 in the Receiver Operating Characteristic (ROC) curve in Group 1 and there wasn't any significant correlation between preoperative NLR and mortality rates in the patients whose NLRs were above this curve. The threshold value was determined as 4.07 in Group 2 and there was a significant relation between preoperative NLR and mortality (p<0,01). No relation was found between NLR and mortality when all the examined patients were considered (p>0.05).

CONCLUSION

NLR that can be easily calculated, can be used as a mortality predictor in the patients of advanced age who will undergo isolated CABG procedure.

Significance of preoperative total lymphocyte count as a prognostic criterion in adult cardiac surgery

BACKGROUND

Evaluation of operational risk is a consequential goal in perioperative management of patients in cardiac surgery. Preoperative total lymphocyte count (PTLC) is a prognostic criterion of adverse major cardiovascular outcomes.

OBJECTIVES

The purpose of this study was to investigate the prognostic value of PTLC as an independent predictor of postoperative morbidity and mortality in cardiac surgery.

PATIENTS AND METHODS

Of 1604 patients scheduled for cardiac surgery between September, 2012 and March, 2013, a total of 1171 consecutive patients underwent elective primary valvular heart surgery and coronary artery bypass grafting. The patients were divided to three groups according to their PTLCs. The baseline characteristics and postoperative mortality and morbidity of the patients as well as the intensive care unit (ICU) stay according to the PTLCs were recorded and analyzed. The only inclusion criterion was a preoperative complete blood count. Exclusion criteria included: ages under 18 or over 80 years old, emergency surgery, adult patients with congenital heart disease and previous open heart surgery, and patients with any bacterial or viral infection during two weeks before the surgery. Protocol of anesthetic medications was used in all the patients similarly and according to standard. All the patients were admitted to the ICU after the surgery.

RESULTS

A PTLC < 1500 cells/µL was associated with significantly high mortality and morbidity (P = 0.0001). In-hospital mortality and major composite morbidity were 9.65% and 28.4%, respectively. Low PTLC was associated with more frequent need for inotropic and intra-aortic balloon pump (IABP) support (P < 0.001), dialysis-dependent acute renal failure (P = 0.0001), postoperative superficial wound infections (P = 0.0001) and prolong ICU stay (P = 0.0001).

CONCLUSIONS

Our study results showed that low PTLC was an independent, valuable prognostic criterion, with high sensitivity and specificity for evaluation of postoperative morbidity and mortality in cardiac surgery.

Organ protective mechanisms common to extremes of physiology: a window through hibernation biology

Supply and demand relationships govern survival of animals in the wild and are also key determinants of clinical outcomes in critically ill patients. Most animals' survival strategies focus on the supply side of the equation by pursuing territory and resources, but hibernators are able to anticipate declining availability of nutrients by reducing their energetic needs through the seasonal use of torpor, a reversible state of suppressed metabolic demand and decreased body temperature. Similarly, in clinical medicine the majority of therapeutic interventions to care for critically ill or trauma patients remain focused on elevating physiologic supply above critical thresholds by increasing the main determinants of delivery of oxygen to the tissues (cardiac output, perfusion pressure, hemoglobin concentrations, and oxygen saturation), as well as increasing nutritional support, maintaining euthermia, and other general supportive measures. Techniques, such as induced hypothermia and preconditioning, aimed at diminishing a patient's physiologic requirements as a short-term strategy to match reduced supply and to stabilize their condition, are few and underutilized in clinical settings. Consequently, comparative approaches to understand the mechanistic adaptations that suppress metabolic demand and alter metabolic use of fuel as well as the application of concepts gleaned from studies of hibernation, to the care of critically ill and injured patients could create novel opportunities to improve outcomes in intensive care and perioperative medicine.

Association of total white cell count with mortality and major adverse events in patients with peripheral arterial disease: a systematic review

OBJECTIVES

Peripheral arterial disease (PAD) is principally caused by atherosclerosis, an established inflammatory disease. Total white cell count (TWCC) is a marker of inflammation and has been associated with outcomes for patients with inflammatory diseases. The aim of this systematic review was to assess the association of TWCC with mortality and major adverse events (MAEs) in PAD patients.

METHODS

Studies investigating the association of TWCC with outcome in patients with PAD were identified by a literature search using the Medline and Cochrane databases. To be eligible for inclusion, studies needed to investigate the association of TWCC with mortality or a composite endpoint that included mortality in patients with PAD. Studies were excluded when the primary focus was carotid artery disease, aortic aneurysmal disease, intracranial vascular disease, or rheumatoid arthritis and treatment with chemotherapy or transplantation of stem cells. Secondary searching of reference lists and relevant reviews was performed.

RESULTS

Ten studies including 8,490 patients with PAD met the inclusion criteria. All studies investigated more than 100 patients with four studies assessing more than 1,000 patients. Study quality varied with well-established risk factors of outcome such as age, smoking, diabetes, and the ankle brachial index being adjusted for inconsistently. The study populations were also disparate. Few studies reported relative risk and 95% confidence intervals for the association of TWCC with mortality or MAE. TWCC was positively and significantly associated with death alone in four of five studies investigating 3,387 patients. TWCC was positively and significantly associated with MAE in five of six studies investigating a total of 6,846 patients.

CONCLUSIONS

Current evidence suggests a positive association of TWCC with mortality and MAEs in patients with PAD. Further well-designed prospective studies are required with high-quality analysis and more complete reporting of outcomes.

Is leukocytosis a predictor for recurrence of ischemic events after coronary artery bypass graft surgery? A cohort study

Objective. Studies have shown that inflammation plays an important role in pathogenesis of coronary artery disease. The present study was designed to evaluate the role of high WBC count before CABG in predicting the risk of ischemic events after CABG. Methods and Results. This prospective study was carried out on 380 patients who underwent CABG surgery. Ninety seven patients (25.5%) had recurrent ischemic event. Mean WBC count before CABG surgery in patients with recurrent ischemic event was 7267 mic/lit ± 1863, which was significantly higher than the others, with a mean WBC count of 6721 mic/lit ± 1734 (P = 0.011). Patients with a WBC count more than 6000 mic/lit were at the highest risk for recurrent ischemic event (OR = 2.11, 95% CI = 1.18–3.44, P = 0.009). After adjustment for age, sex, family history, smoking, hyperlipidemia, Logestic Euro score, post opretive enzyme release (CK.mb), arterial graft and BMI, the relationship between the group with WBC count higher than 6000 mic/lit and recurrent of ischemic event remained significant (OR = 2.25, 95% CI = 1.2 to 4, P = 0.005). Conclusions. High WBC count before CABG surgery is an independent risk factor for ischemic events one year after the surgery.

Neutrophils and clinical outcomes in patients with acute coronary syndromes and/or cardiac revascularisation. A systematic review on more than 34,000 subjects

Some studies have suggested that high levels of total white blood cell (WBC) count and C-reactive protein (CRP) may be considered as independent prognostic factors in patients with acute coronary syndromes (ACS) and/or after cardiac revascularisation by percutaneous coronary intervention or coronary artery bypass grafting surgery. Evidence on the role of neutrophils in cardiovascular disease is less compelling. Therefore, we conducted a systematic review of the literature with the aim of identifying all the available evidence to clarify the role of neutrophils (absolute or relative count, neutrophil/lymphocyte ratio) as a prognostic risk factor in patients with ACS and/or cardiac revascularisation. All published studies evaluating the role of neutrophils as a risk factor for clinical outcomes were assessed using the MEDLINE and EMBASE databases. Study selection, data extraction and validity assessment was performed independently by two reviewers. Twenty-one studies (17 of which had positive results) for a total of more than 34,000 patients were included. Ten of 13 studies in ACS patients found that neutrophils measured on-admission are related to mortality rate and/or to major adverse clinical events. A predictive value of neutrophils after cardiac revascularisation procedures was reported in seven out of eight studies. Most of the studies showed that neutrophils were independent predictors of cardiovascular outcomes when analysed concomitantly with other markers of inflammation (WBC, CRP). The findings of our systematic review highlight the potential application of this inexpensive and readily available inflammatory marker for risk stratification in patients with ACS and/or cardiac revascularisation.

Leukocytosis as a predictor for non-infective mortality and morbidity

Leukocytosis (raised concentration of white cells in the blood) is commonly associated with infection or inflammation, but can occur in a wide variety of other conditions. Leukocytosis has also been linked with increased mortality and morbidity in a number of studies. We have systematically reviewed the relevant literature, which clearly demonstrates an association between leukocytosis and mortality-particularly due to cardiovascular or cerebrovascular causes. The mechanisms of this effect are uncertain but, when combined with other markers predictive of death, leukocytosis may contribute to modelling systems to predict in-patient mortality risk.

Does smoking status affect the association between baseline white blood cell count and in-hospital mortality of patients presented with Acute Coronary Syndrome? The Greek study of Acute Coronary Syndromes (GREECS)

OBJECTIVES

In this work, we sought to investigate whether smoking status modifies the effect of white blood cell count (WBC) on in-hospital mortality of patients presented with acute coronary syndrome (ACS).

METHODS

A sample of 6 hospitals located in Greek urban and rural regions was selected. We recorded almost all consecutive patients due to ACS, from October 2003 to September 2004 (2172 patients).

RESULTS

The mean (standard deviation) WBC count was 9.14 (3.16) cells/dL. The in-hospital mortality rate was higher in patients of upper tertile compared to those of lower tertile of WBC (p<0.05). The interaction between smoking status and WBC count revealed that smoking status modifies the effect of WBC count on mortality (p for interaction=0.004). Thus, stratified analysis showed that the WBC count is an independent predictor of in-hospital mortality only among former and current smokers.

CONCLUSIONS

We demonstrated that the association between WBC count and mortality modified by smoking status and that WBC count is a predictor of mortality only among former and current smokers.

Preoperative neutrophil-lymphocyte ratio and outcome from coronary artery bypass grafting

BACKGROUND

An elevated preoperative white blood cell count has been associated with a worse outcome after coronary artery bypass grafting (CABG). Leukocyte subtypes, and particularly the neutrophil-lymphocyte (N/L) ratio, may however, convey superior prognostic information. We hypothesized that the N/L ratio would predict the outcome of patients undergoing surgical revascularization.

METHODS

Baseline clinical details were obtained prospectively in 1938 patients undergoing CABG. The differential leukocyte was measured before surgery, and patients were followed-up 3.6 years later. The primary end point was all-cause mortality.

RESULTS

The preoperative N/L ratio was a powerful univariable predictor of mortality (hazard ratio [HR] 1.13 per unit, P < .001). In a backward conditional model, including all study variables, it remained a strong predictor (HR 1.09 per unit, P = .004). In a further model, including the European system for cardiac operative risk evaluation, the N/L ratio remained an independent predictor (HR 1.08 per unit, P = .008). Likewise, it was an independent predictor of cardiovascular mortality and predicted death in the subgroup of patients with a normal white blood cell count. This excess hazard was concentrated in patients with an N/L ratio in the upper quartile (>3.36).

CONCLUSION

An elevated N/L ratio is associated with a poorer survival after CABG. This prognostic utility is independent of other recognized risk factors.