Does Preoperative Hemoglobin Independently Predict Short-Term Outcomes After Coronary Artery Bypass Graft Surgery?

Pre-operative anaemia-does it influence post-operative outcomes after isolated coronary artery bypass grafting?

Introduction

Preoperative anaemia is prevalent in a number of patients undergoing coronary artery bypass grafting. Studies provide conflicting results due to several reasons including variation in the threshold of haematocrit used to define anaemia. We aimed to assess the independent effect of preoperative anaemia on outcomes in patients undergoing off pump coronary artery bypass grafting (OPCAB).

Methods

In this retrospective study, patients with a hemoglobin level less than 11g/dl (haematocrit <33%) were considered to have moderate-to-severe anaemia as per the recommendations of the World Health Organization. Association between haematocrit <33% and mortality as well as adverse post-operative outcomes was assessed. Multivariable logistic regression (MLR) was carried out to assess the independent effect of haematocrit<33% on 30-day mortality and other outcomes.

Results

The study included 4957 consecutive patients undergoing isolated OPCAB surgery between 2015 and 2020. Out of 4957, 635 (12.8%) had haematocrit <33% and 4322 (81.2%) had haematocrit ≥33%. Patients with haematocrit < 33% had a 30-day mortality of 13 (2%) compared to 38 (0.9%) in patients without anaemia and had a greater requirement for blood transfusion (p<0.0001). It was also associated with an increased incidence of renal failure (p<0.0001), tracheostomy (p=.0.012) and risk of re-intubation (p=0.006). On multiple linear regression (MLR), haematocrit < 33% was not an independent predictor of 30-day mortality odds ratio (OR) 1.47, 95% confidence interval (CI) 0.745-2.917; p=0.26. It was however an important independent risk factor for blood transfusion (OR 1.80, 95% CI 1.29-2.50, p<0.001) and renal failure (OR 3.06, 95% CI 1.338-7.012, p=0.008). The receiver operating characteristic (ROC)-area under the curve (AUC) was 0.63 suggesting moderate discriminatory value of haematocrit < 33% for 30-day mortality.

Conclusion

Haematocrit < 33% is an important risk factor for adverse outcomes following isolated, primary, elective OPCAB.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s12055-024-01746-1.

Analysis of Anemia, Transfusions, and CABG Outcomes in The Society of Thoracic Surgeons National Database

BACKGROUND

This study characterized the association of preoperative anemia and intraoperative red blood cell (RBC) transfusion on outcomes of elective coronary artery bypass grafting (CABG).

METHODS

Data from 53,856 patients who underwent CABG included in The Society of Thoracic Surgeons (STS) Adult Cardiac Database in 2019 were used. The primary outcome was operative mortality. Secondary outcomes were postoperative complications. The association of anemia with outcomes was analyzed with multivariable regression models. The influence of intraoperative RBC transfusion on the effect of preoperative anemia on outcomes was studied using mediation analysis.

RESULTS

Anemia was present in 25% of patients. Anemic patients had a higher STS Predicted Risk of Operative Mortality (1.2% vs 0.7%; P < .001). Anemia was associated with operative mortality (odds ratio [OR], 1.27; 99.5% CI, 1.00-1.61; P = .047), postoperative RBC transfusion (OR, 2.28; 99.5% CI, 2.12-2.44; P < .001), dialysis (OR, 1.58; 99.5% CI, 1.19-2.11; P < .001), and prolonged intensive care unit and hospital length of stay. Intraoperative RBC transfusion largely mediated the effects of anemia on mortality (76%), intensive care unit stay (99%), and hospital stay, but it only partially mediated the association with dialysis (34.9%).

CONCLUSIONS

Preoperative anemia is common in patients who undergo CABG and is associated with increased postoperative risks of mortality, complications, and RBC transfusion. However, most of the effect of anemia on mortality is mediated through intraoperative RBC transfusion.

The additive effects of anaemia and transfusion on long-term survival after coronary artery bypass surgery

OBJECTIVES

To compare the independent and combined effects of anaemia and red blood cell transfusion on late survival after isolated coronary artery bypass grafting.

METHODS

Retrospective analysis of 5243 consecutive patients undergoing primary isolated coronary artery bypass grafting, performed from 2000 to 2015, in a Portuguese Academic Hospital. We identified 1649 patients with preoperative anaemia (A+) and 1422 patients who received a perioperative transfusion (T+)-the 4 possible combinations allowed for the creation of 4 subgroups (A-/T-, A-/T+, A+/T- and A+/T+). The primary endpoint was all-cause mortality at 10 years. We employed inverse probability weighting to control for confounding variables.

RESULTS

Thirty-one percent of the patients had preoperative anaemia, and 27.0% had at least one packed red blood cell transfusion. Inverse probability weighting was effective in eliminating differences in all significant baseline characteristics. The primary endpoint of all-cause mortality at 10 years occurred in 568 patients (20.5%) in the A-/T- group, as compared with 204 (24.4%) in the A-/T+ group (hazard ratio, 1.14; 95% confidence interval, 1.00 to 1.31; P = 0.053), 358 (33.8%) in the A+/T- group (hazard ratio, 1.53; 95% confidence interval, 1.38 to 1.71; P < 0.001), 254 (43.6%) in the A+/T+ group (hazard ratio, 2.25; 95% confidence interval, 1.97 to 2.56; P < 0.001).

CONCLUSIONS

This longitudinal, population-level study emphasizes the adverse long-term outcomes of preoperative anaemia and perioperative red blood cell transfusion. It stresses the importance of an evidence-based, multimodal and multidisciplinary approach to conserving blood resources and optimizing outcomes in patients at high risk for transfusion.

Preoperative anemia and anemia treatment in cardiac surgery: a systematic review and meta-analysis

PURPOSE

We aimed to conduct a systematic review and meta-analysis to assess the effects of anemia and anemia severity on patient outcomes in cardiac surgery and determine whether preoperative treatments confer postoperative benefit.

SOURCE

We searched four international databases for observational and randomized studies published until 1 October 2022. Study quality was assessed via Newcastle-Ottawa scores and the Cochrane Risk-of-Bias 2 tool and certainty of evidence was rated with the Grading of Recommendations, Assessment, Development and Evaluations approach. We conducted random-effects meta-analyses for our primary outcome of mortality, for secondary outcomes including length of stay (LOS) in the hospital and intensive care unit, and for postsurgical complications. As part of a secondary analysis, we analyzed short-term preoperative anemia treatments and conducted trial sequential analysis of randomized trials to assess the efficacy of these treatment programs.

PRINCIPAL FINDINGS

We included 35 studies (159,025 patients) in our primary meta-analysis. Preoperative anemia was associated with increased mortality (odds ratio [OR], 2.5; 95% confidence interval [CI], 2.2 to 2.9; P < 0.001, high certainty). Study-level meta-regression revealed lower hemoglobin levels and studies with lower proportions of male patients to be associated with increased risk of mortality. Preoperative anemia was also associated with an increase in LOS and postsurgical complications. Our secondary analysis (seven studies, 1,012 patients) revealed short-term preoperative anemia treatments did not significantly reduce mortality (OR, 1.1; 95% CI, 0.65 to 1.9; P = 0.69). Trial sequential analysis suggested that there was insufficient evidence to conclude if treatment programs yield any benefit or harm.

CONCLUSIONS

Preoperative anemia is associated with mortality and morbidity after cardiac surgery. More research is warranted to test the efficacy of current anemia treatment programs.

STUDY REGISTRATION

PROSPERO (CRD42022319431); first submitted 17 April 2023.

What we should consider to facilitate recovery of the hematological profile in all patients after pancreaticoduodenectomy: the role of preoperative intravenous iron treatment

BACKGROUND

In pancreaticoduodenectomy (PD), the duodenum and upper jejunum responsible for iron absorption are removed, which can lead to massive hemorrhage during surgery and cause iron deficiency anemia after PD. The aim of this study was to evaluate overall changes in hematologic profiles of patients who underwent pancreaticoduodenectomy. Effect of preoperative intravenous iron treatment on recovery of anemia after surgery was also investigated.

METHODS

From March 2021 to December 2021, patients who underwent curative PD at our institution due to periampullary lesions were enrolled. They were divided into two groups according to whether or not iron was administered before surgery. In the IV iron group, all patients had been routinely administered with 1000 mg of ferric carboxymaltose intravenously once about 3-7 days before the operation day. Contrarily, patients in the control group did not receive intravenous iron before PD. Changes in hematological profile were measured preoperatively and at 5, 14, and 30 days postoperatively. Clinical results of the two groups were compared and analyzed. Additionally, a subgroup analysis was performed for selected non-anemic patients who had preoperative hemoglobin level of 12.0 g/dl or higher to compare changes in hematologic profiles between the two groups.

RESULTS

Thirty patients of the IV iron group and 34 patients of the control group were analyzed. Although no difference was observed in postoperative complications or mortality, hemoglobin and iron levels were recovered significantly faster at two weeks postoperatively in the IV iron group than in the control group. Iron levels were significantly higher in the IV iron group throughout the postoperative period. In subgroup analysis conducted for non-anemic patients, hemoglobin levels were recovered significantly faster and maintained higher in the IV iron group throughout the postoperative period, although baseline levels of hemoglobin were similar between the two groups. In addition, the length of intensive care unit stay was significantly shorter in the IV iron group than in the control group.

CONCLUSIONS

Preoperative intravenous iron treatment might be effective in facilitating recovery of hematologic profiles of patients during the recovery period after PD regardless of the presence of preoperative anemia, thus preventing postoperative iron deficiency anemia.

Outcomes of Left Main Revascularization in Patients with Anemia: Gulf Left Main Registry

INTRODUCTION

The aim of this study was to evaluate the effects of baseline anemia and anemia following revascularization on outcomes in patients with unprotected left main coronary artery (ULMCA) disease.

METHODS

This was a retrospective, multicenter, observational study conducted between January 2015 and December 2019. The data on patients with ULMCA who underwent revascularization through percutaneous coronary intervention (PCI) or coronary artery bypass graft (CABG) were stratified by the hemoglobin level at baseline into anemic and non-anemic groups to compare in-hospital events. The pre-discharge hemoglobin following revascularization was categorized into very low (<80 g/L for men and women), low (≥80 and ≤119 g/L for women and ≤129 g/L for men), and normal (≥130 g/L for men and ≥120 g/L for women) to assess impact on follow-up outcomes.

RESULTS

A total of 2,138 patients were included, 796 (37.2%) of whom had anemia at baseline. A total of 319 developed anemia after revascularization and moved from being non-anemic at baseline to anemic at discharge. There was no difference in hospital major adverse cardiac and cerebrovascular event (MACCE) and mortality between CABG and PCI in anemic patients. At a median follow-up time of 20 months (interquartile range [IQR]: 27), patients with pre-discharge anemia who underwent PCI had a higher incidence of congestive heart failure (CHF) (p < 0.0001), and those who underwent CABG had significantly higher follow-up mortality (HR: 9.85 (95% CI: 2.53-38.43), p = 0.001).

CONCLUSION

In this Gulf LM study, baseline anemia had no impact upon in-hospital MACCE and total mortality following revascularization (PCI or CABG). However, pre-discharge anemia is associated with worse outcomes after ULMCA disease revascularization, with significantly higher all-cause mortality in patients who had CABG, and a higher incidence of CHF in PCI patients, at a median follow-up time of 20 months (IQR: 27).

Machine learning-based prediction of 1-year mortality in hypertensive patients undergoing coronary revascularization surgery

BACKGROUND

Machine learning (ML) has shown promising results in all fields of medicine, including preventive cardiology. Hypertensive patients are at higher risk of mortality after coronary artery bypass graft (CABG) surgery; thus, we aimed to design and evaluate five ML models to predict 1-year mortality among hypertensive patients who underwent CABG.

HYOTHESIS

ML algorithms can significantly improve mortality prediction after CABG.

METHODS

Tehran Heart Center's CABG data registry was used to extract several baseline and peri-procedural characteristics and mortality data. The best features were chosen using random forest (RF) feature selection algorithm. Five ML models were developed to predict 1-year mortality: logistic regression (LR), RF, artificial neural network (ANN), extreme gradient boosting (XGB), and naïve Bayes (NB). The area under the curve (AUC), sensitivity, and specificity were used to evaluate the models.

RESULTS

Among the 8,493 hypertensive patients who underwent CABG (mean age of 68.27 ± 9.27 years), 303 died in the first year. Eleven features were selected as the best predictors, among which total ventilation hours and ejection fraction were the leading ones. LR showed the best prediction ability with an AUC of 0.82, while the least AUC was for the NB model (0.79). Among the subgroups, the highest AUC for LR model was for two age range groups (50-59 and 80-89 years), overweight, diabetic, and smoker subgroups of hypertensive patients.

CONCLUSIONS

All ML models had excellent performance in predicting 1-year mortality among CABG hypertension patients, while LR was the best regarding AUC. These models can help clinicians assess the risk of mortality in specific subgroups at higher risk (such as hypertensive ones).

Machine learning algorithms for predicting mortality after coronary artery bypass grafting

Background

As the era of big data analytics unfolds, machine learning (ML) might be a promising tool for predicting clinical outcomes. This study aimed to evaluate the predictive ability of ML models for estimating mortality after coronary artery bypass grafting (CABG).

Materials and methods

Various baseline and follow-up features were obtained from the CABG data registry, established in 2005 at Tehran Heart Center. After selecting key variables using the random forest method, prediction models were developed using: Logistic Regression (LR), Support Vector Machine (SVM), Naïve Bayes (NB), K-Nearest Neighbors (KNN), Extreme Gradient Boosting (XGBoost), and Random Forest (RF) algorithms. Area Under the Curve (AUC) and other indices were used to assess the performance.

Results

A total of 16,850 patients with isolated CABG (mean age: 67.34 ± 9.67 years) were included. Among them, 16,620 had one-year follow-up, from which 468 died. Eleven features were chosen to train the models. Total ventilation hours and left ventricular ejection fraction were by far the most predictive factors of mortality. All the models had AUC &gt; 0.7 (acceptable performance) for 1-year mortality. Nonetheless, LR (AUC = 0.811) and XGBoost (AUC = 0.792) outperformed NB (AUC = 0.783), RF (AUC = 0.783), SVM (AUC = 0.738), and KNN (AUC = 0.715). The trend was similar for two-to-five-year mortality, with LR demonstrating the highest predictive ability.

Conclusion

Various ML models showed acceptable performance for estimating CABG mortality, with LR illustrating the highest prediction performance. These models can help clinicians make decisions according to the risk of mortality in patients undergoing CABG.

Critical Preoperative Hemoglobin Value to Predict Anemia-Related Complications After Cardiac Surgery

OBJECTIVES

Preoperative anemia is frequent in patients undergoing cardiac surgery and is associated with increased postoperative complications. The purpose of this observational study was to estimate the critical preoperative hemoglobin threshold associated with the occurrence of complications after cardiac surgery.

DESIGN

A retrospective observational cohort study.

SETTING

A tertiary-care medical center from January 2019 to April 2020.

PARTICIPANTS

A total of 1,004 patients undergoing elective cardiac surgery were included.

INTERVENTIONS

None (observational study).

MEASUREMENTS AND MAIN RESULTS

The primary study endpoint was to define the hemoglobin threshold that predicted the occurrence of postoperative major complications after elective cardiac surgery. Postoperative complications were a composite criterion, including transient ischemic attack or stroke, myocardial infarction, acute kidney injury, respiratory failure, mediastinitis, or mesenteric ischemia. A discrimination threshold was determined by using receiver operating characteristic curves. The discrimination threshold for hemoglobin concentration with the best sensitivity/specificity ratio for the occurrence of postoperative complications was 13 g/dL for male patients and 11.8 g/dL for female patients. The incidence of postoperative complications was 17.2% in the total population. Independent risks were preoperative hemoglobin concentration, red blood cell transfusion, European System for Cardiac Operative Risk Evaluation II, and the type of surgery.

CONCLUSIONS

The critical preoperative hemoglobin thresholds associated with the occurrence of postoperative complications with the best sensitivity/specificity ratio were 13 g/dL for men and 11.8 g/dL for women, which were very similar to the World Health Organization criteria defining anemia.

Preoperative Anemia is Associated with Increased Intraoperative Mortality in Patients Undergoing Cardiac Surgery

Objectives

We sought to investigate the incidence of preoperative anemia in cardiac surgery and its association with outcomes.

Methods

A retrospective review of clinical, laboratory, and transfusion data for all patients who underwent cardiac surgery at Sultan Qaboos University Hospital between 2008 and 2014 was performed. Patients were divided into two groups, anemic and non-anemic, with anemia defined as hemoglobin levels < 13 g/dL (males) and < 12 g/dL (females). Clinical variables were compared using chi-square and independent t-test. Factors influencing preoperative mortality were analyzed using multivariate binary logistics regression.

Results

A total of 599 patients (69.9% males and 30.1% females) were included in the study; 69.3% underwent coronary artery bypass surgery. Preoperative anemia was found in 76.1% of females and 26.7% of male patients. Rates of intraoperative red blood cell transfusions were higher among anemic patients (75.9% vs. 52.3%, p < 0.001). Anemic patients had a worse risk profile with higher incidence of diabetes mellitus (53.8% vs. 38.9%, p < 0.001), congestive heart failure (51.4% vs. 28.3%, p < 0.001), arrhythmia (16.5% vs. 8.6%, p = 0.004), and cerebrovascular disease (10.0% vs. 4.9%, p = 0.015). In addition, they had a higher risk of overall mortality (6.4% vs. 2.6%, p = 0.023). Preoperative anemia remained a risk factor for intraoperative mortality after logistic regression (odds ratio = 4.08, 95% confidence interval: 1.43–11.66; p = 0.009).

Conclusions

Preoperative anemia in cardiac surgery is independently associated with increased intraoperative mortality and early readmission rates post-surgery.

Six-month prognostic impact of hemodynamic profiling by short minimally invasive monitoring after cardiac surgery

Introduction: Studies have shown that a hemodynamic-guided therapy improves the post operative outcomes of high-risk patients.This study, evaluated if a short period through minimally invasive hemodynamic monitoring, pressure recording analytical method (PRAM), on admission to a post-cardiac surgery step-down unit (SDU), may identify patients at higher risk of 6-month adverse events after cardiac surgery. Methods: From December 2016-May 2017,173 patients were admitted in SDU within 24-48 hours of major cardiac surgery procedure, and submitted to clinical, laboratoristic and echocardiographic evaluation and a 1-hour PRAM recording to obtain a "biohumoral snapshot" of individual patient's.156 173 patients (17 patients were lost at follow-up) were phone interviewed six months after surgery,to evaluate, as a composite end-point, the adverse events during follow-up. A multivariable logistic regression analysis was used to identify a model clinical-biohumoral (CBM) and clinical-biohumoral hemodynamics (CBHM). Results: No data from past clinical history and no conventional risk score (EuroScore II, STS score)independently predicted the risk of 6-month major events in our study. The risk of adverse events at six-month follow-up was directly related, in the CBM, to sustained post-operative cardiac arrhythmias, higher values of NT-proBNP and of arterial pH; inversely related to values of hs-C-reactive protein (hs-CRP) and, in the CBHM, to low values of cardiac cycle efficiency (CCE) and dP/dt_max. Conclusion: Our study although limited by its observational nature and by the limited number of patients enrolled, showed that a short period of minimally invasive hemodynamic monitoring increased the accuracy to identify patients at major risk of mid-term events after cardiac surgery.

Prognostic Interplay of Chronic Kidney Disease, Anemia, and Diabetes in Coronary Bypass Surgery

BACKGROUND

Chronic kidney disease and anemia often coexist and may accompany diabetes; all 3 conditions are associated with worse cardiovascular outcomes. This study investigated the prognostic implications of anemia and chronic kidney disease for mortality among patients undergoing coronary artery-bypass grafting surgery and examined whether outcomes are related to the presence of diabetes.

METHODS

This retrospective study included 1180 patients undergoing coronary artery-bypass grafting. Long-term mortality (mean follow-up, 8.6 ± 4.2 years) was examined in relation to preoperative anemia, chronic kidney disease, and diabetes. Prognostic interplay of the 3 risk factors was evaluated.

RESULTS

Chronic kidney disease, anemia, and diabetes (20%, 25%, and 43% of patients, respectively), were independent risk predictors for mortality. Compared with patients with neither chronic kidney disease nor anemia, the adjusted hazard ratios (HRs) for mortality were 1.87 (95% confidence interval [CI], 1.35 to 2.59) in chronic kidney disease only, 1.75 (95% CI, 1.30 to 2.35) in anemia only, and 2.69 (95% CI, 1.91 to 3.78) in patients with both conditions. The pattern of association of chronic kidney disease and anemia with mortality was similar in patients with and without diabetes. However, mortality risk was higher in patients with diabetes in each risk category-neither chronic kidney disease nor anemia: HR, 1.69 (95% CI, 1.20 to 2.39) vs HR, 1 (reference); chronic kidney disease only: HR, 2.68 (95% CI, 1.59 to 4.52) vs HR, 2.10 (95% CI, 1.38 to 3.20); anemia only: HR, 2.73 (95% CI, 1.83 to 4.07) vs HR, 1.94 (95% CI, 1.23 to 3.08); and both chronic kidney disease and anemia: HR, 4.44 (95% CI, 2.88 to 6.85) vs HR, 2.72 (95% CI, 1.58 to 4.69).

CONCLUSIONS

In patients undergoing coronary artery-bypass grafting, anemia and chronic kidney disease have significant prognostic implications for long-term mortality. Their effect on mortality was cumulatively associated with adverse impacts of diabetes.

Impact of Preoperative Anemia on Perioperative Outcomes in Patients Undergoing Elective Colorectal Surgery

Aim

To evaluate the impact of preoperative anemia (POA) on perioperative outcomes in patients undergoing elective surgery for colorectal cancer (CRC).

Methods

A total of 326 CRC patients were enrolled. POA was defined as a hemoglobin (Hb) concentration ≤ 12 g/dl. Univariable and multivariable analyses were performed to assess the impact of POA on the risks of postoperative complications like surgical site infection (SSI).

Results

Patients with colon cancer presented higher rate of POA than patients with rectal cancer (60% versus 40% for colon cancer versus rectal cancer). In addition, female patients and patients with large tumor mass (>4 cm) had a higher rate of POA than male patients and patients with small tumor (≤4 cm), respectively. Upon univariable analysis, CRC patients with POA had a higher rate of incisional SSI than patients without POA (12% versus 6%, P = 0.04). However, POA was not associated with other postoperative complications, like anastomotic leak, organ space SSI, and bleeding. Upon multivariable analysis, POA and stoma formation were identified as two independent risk factors for incisional SSI (OR (95%CI): 2.44 (1.09–5.49) for POA versus no POA and 2.64 (1.20–5.81) for stoma formation versus no stoma formation).

Conclusions

POA was an independent risk factor for incisional surgical site infection after colorectal resection for CRC, and correcting POA should be considered before elective surgery.

Propensity-matched analysis of association between preoperative anemia and in-hospital mortality in cardiac surgical patients undergoing valvular heart surgeries

Introduction:

Anaemia is associated with increased post-operative morbidity and mortality. We retrospectively assess the relationship between preoperative anaemia and in-hospital mortality in valvular cardiac surgical population.

Materials and Methods:

Data from consecutive adult patients who underwent valvular repair/replacement at our institute from January 2010 to April 2014 were collected from hospital records. Anaemia was defined according to WHO criteria (hemoglobin <13g/dl for males and <12g/dl for females). 1:1 matching was done for anemic and non-anemic patients based on propensity for potentially confounding variables. Logistic regression was used to evaluate the relationship between anaemia and in-hospital mortality. MatchIt package for R software was used for propensity matching and SPSS 16.0.0 was used for statistical analysis.

Results:

2449 patients undergoing valvular surgery with or without coronary artery grafting were included. Anaemia was present in 37.1% (33.91% among males & 40.88% among females). Unadjusted OR for mortality was 1.6 in anemic group (95% Confidence Interval [95% CI] – 1.041-2.570; p=0.033). 1:1 matching was done on the basis of propensity score for anaemia (866 pairs). Balancing was confirmed using standardized differences. Anaemia had an OR of 1.8 for mortality (95% CI- 1.042 to 3.094, P=0.035). Hematocrit of < 20 on bypass was associated with higher mortality.

Conclusion:

Preoperative anaemia is an independent risk factor associated with in-hospital mortality in patients undergoing valvular heart surgery.

Meta-analysis of the association between preoperative anaemia and mortality after surgery

BACKGROUND

Numerous published studies have explored associations between anaemia and adverse outcomes after surgery. However, there are no evidence syntheses describing the impact of preoperative anaemia on postoperative outcomes.

METHODS

A systematic review and meta-analysis of observational studies exploring associations between preoperative anaemia and postoperative outcomes was performed. Studies investigating trauma, burns, transplant, paediatric and obstetric populations were excluded. The primary outcome was 30-day or in-hospital mortality. Secondary outcomes were acute kidney injury, stroke and myocardial infarction. Predefined analyses were performed for the cardiac and non-cardiac surgery subgroups. A post hoc analysis was undertaken to evaluate the relationship between anaemia and infection. Data are presented as odds ratios (ORs) with 95 per cent c.i.

RESULTS

From 8973 records, 24 eligible studies including 949 445 patients were identified. Some 371 594 patients (39·1 per cent) were anaemic. Anaemia was associated with increased mortality (OR 2·90, 2·30 to 3·68; I(2)  = 97 per cent; P < 0·001), acute kidney injury (OR 3·75, 2·95 to 4·76; I(2)  = 60 per cent; P < 0·001) and infection (OR 1·93, 1·17 to 3·18; I(2)  = 99 per cent; P = 0·01). Among cardiac surgical patients, anaemia was associated with stroke (OR 1·28, 1·06 to 1·55; I(2)  = 0 per cent; P = 0·009) but not myocardial infarction (OR 1·11, 0·68 to 1·82; I(2)  = 13 per cent; P = 0·67). Anaemia was associated with an increased incidence of red cell transfusion (OR 5·04, 4·12 to 6·17; I(2)  = 96 per cent; P < 0·001). Similar findings were observed in the cardiac and non-cardiac subgroups.

CONCLUSION

Preoperative anaemia is associated with poor outcomes after surgery, although heterogeneity between studies was significant. It remains unclear whether anaemia is an independent risk factor for poor outcome or simply a marker of underlying chronic disease. However, red cell transfusion is much more frequent amongst anaemic patients.

Preoperative anemia increases mortality and postoperative morbidity after cardiac surgery

Background

Anemia is an established adverse risk factor in cardiovascular disease. However, the effect of preoperative anemia is not well defined in heart surgery. This study evaluates the effect of preoperative anemia on early clinical outcomes in patients undergoing cardiac surgery.

Methods

A retrospective, observational, cohort study of prospectively collected data was undertaken on 7,738 consecutive patients undergoing heart surgery between April 2003 and February 2009. Of these, 1,856 patients with preoperative anemia were compared to 5,882 patients without anemia (control group). According to the World Health Organization, anemia was defined as hemoglobin level < 13 g/dl for men and <12 g/dl for women. Selection bias not controlled by multivariable methods was assessed with propensity-adjustment method.

Results

Overall mortality was 2.1%. Preoperative anemia was associated with tripling in the risk of death (4.6% vs 1.5%, p < 0.0001) and postoperative renal dysfunction (18.5% vs 6.5%, p < 0.0001). There was also a significant difference between the anemic and non-anemic group in the risk of postoperative stroke (1.9% vs 1.1%, p = 0.008), atrial fibrillation (36.7% vs 33%, p = 0.003) and length of hospital stay > 7 days (54% vs 36.7%, p < 0.0001). In propensity-adjusted, multivariable logistic regression, preoperative anemia was an independent predictor of mortality (odds ratio [OR] 1.44, 95% confidence interval [CI] 1.02 to 2.03), postoperative renal dysfunction (OR 1.73, 95% CI 1.43 to 2.1) and length of hospital stay > 7 days (OR 1.3, 95% CI 1.15 to 1.47).

Conclusion

In patients undergoing heart surgery, preoperative anemia is associated with an increased risk of mortality and postoperative morbidity.

Preoperative estimated glomerular filtration rate as a significant predictor of long-term outcomes after coronary artery bypass grafting in Japanese patients

PURPOSES

The aim of this retrospective study was to investigate the effect of chronic kidney disease (CKD) on outcomes after coronary artery bypass grafting (CABG), and to determine whether preoperative estimated glomerular filtration rate (eGFR) can be a predictor of long-term outcomes after CABG.

METHODS

486 Japanese patients who underwent isolated CABG between December 2000 and August 2010 were evaluated. Preoperative eGFR was estimated by the Japanese equation according to guidelines from the Japanese Society of Nephrology. We defined CKD as a preoperative eGFR of less than 60 ml/min/1.73 m(2). 203 patients had CKD (CK group) and 283 patients did not (N group).

RESULTS

During a mean observation time of 53 months, the overall survival rate was significantly lower in the CK group than in the N group (p = 0.0044). Similarly, the CK group had significantly more unfavorable results with regard to freedom from cardiac death, major adverse cardiovascular and cerebrovascular events (MACCE), and hemodialysis. Using multivariate analyses, preoperative eGFR was an independent predictor of all-cause mortality (HR 0.983; p = 0.026), cardiac mortality (HR 0.963; p = 0.006), and incidence of MACCE (HR 0.983; p = 0.002).

CONCLUSIONS

The CK group had significantly more unfavorable outcomes than the N group. Preoperative eGFR was an independent predictor of long-term outcomes after CABG in Japanese patients.

Hemoglobin and B-type natriuretic peptide preoperative values but not inflammatory markers, are associated with postoperative morbidity in cardiac surgery: a prospective cohort analytic study

Introduction

Risk stratification in cardiac surgery significantly impacts outcome. This study seeks to define whether there is an independent association between the preoperative serum level of hemoglobin (Hb), leukocyte count (LEUCO), high sensitivity C-reactive protein (hsCRP), or B-type natriuretic peptide (BNP) and postoperative morbidity and mortality in cardiac surgery.

Methods

Prospective, analytic cohort study, with 554 adult patients undergoing cardiac surgery in a tertiary cardiovascular hospital and followed up for 12 months. The cohort was distributed according to preoperative values of Hb, LEUCO, hsCRP, and BNP in independent quintiles for each of these variables.

Results

After adjustment for all covariates, a significant association was found between elevated preoperative BNP and the occurrence of low postoperative cardiac output (OR 3.46, 95% CI 1.53–7.80, p = 0.003) or postoperative atrial fibrillation (OR 3.8, 95% CI 1.45–10.38). For the combined outcome (death/acute coronary syndrome/rehospitalization within 12 months), we observed an OR of 1.93 (95% CI 1.00–3.74). An interaction was found between BNP level and the presence or absence of diabetes mellitus. The OR for non-diabetics was 1.26 (95% CI 0.61–2.60) and for diabetics was 18.82 (95% CI 16.2–20.5). Preoperative Hb was also significantly and independently associated with the occurrence of postoperative low cardiac output (OR 0.33, 95% CI 0.13–0.81, p = 0.016). Both Hb and BNP were significantly associated with the lengths of intensive care unit and hospital stays and the number of transfused red blood cells (p < 0.002). Inflammatory markers, although associated with adverse outcomes, lost statistical significance when adjusted for covariates.

Conclusions

High preoperative BNP or low Hb shows an association of independent risk with postoperative outcomes, and their measurement could help to stratify surgical risk. The ability to predict the onset of atrial fibrillation or postoperative low cardiac output has important clinical implications. Our results open the possibility of designing studies that incorporate BNP measurement as a routine part of preoperative evaluation, and this strategy could improve upon the standard evaluation in terms of reducing adverse postoperative events.

Preoperative hemoglobin level as a predictor of mortality after aortic valve replacement

OBJECTIVES

The predictive value of preoperative hemoglobin (HB) level on the outcome of patients undergoing valve surgery is not well established. This study evaluated the predictive value of preoperative HB level on survival after aortic valve replacement (AVR).

DESIGN

This was a retrospective analysis of prospectively collected data.

SETTING

A single-center study performed in an educational hospital.

PARTICIPANTS

All consecutive patients (n = 1,808) who underwent AVR between January 1998 and December 2010.

INTERVENTIONS AVR MEASUREMENTS AND MAIN RESULTS

Patients were classified into 4 groups according to the preoperative HB level: very low (HB of <12 g/dL in men and <11 g/dL in women), low (HB of 12-13 g/dL in men and 11-12 g/dL in women), normal (HB of 13-14.5 g/dL in men and 12-13.5 g/dL in women), and high normal (HB of ≥14.5 g/dL in men and ≥13.5 g/dL in women). The mean follow-up duration was 5.58±3.5 years, and the median follow-up duration was 5.38 years. The mean preoperative HB was 14±1.6 g/dL for men and 13.0±2.1 g/dL for women. Early mortality (≤30 days) was 6.1% in the very-low-HB group, 5.4% in the low-HB group, 3.2% in the normal HB group, and 2.3% in the high-normal-HB group (p = 0.37). Late mortality (>30 days) was 26.1% in the very-low-HB group, 23.7% in the low-HB group, 17.1% in the normal-HB group, and 12.6% in the high-normal-HB group (p<0.0001). The multivariate logistic regression model did not identify low HB as an independent predictor for early mortality. Cox regression multivariate analysis revealed both HB level, as a continuous variable, (p = 0.006), and very-low-HB level (p<0.0001), as independent predictors of late mortality. Cox regression analyses, corrected for confounders, demonstrated that low-HB level is an independent predictor for higher overall mortality (hazard ratio = 2.00, CI 1.41-2.85, p≤0.0001).

CONCLUSIONS

In patients undergoing AVR, preoperative low-HB level is an independent risk factor for late mortality, but not for early mortality.

Mean platelet volume may predict early clinical outcome after coronary artery bypass grafting

Background

An elevated mean platelet volume is associated with increased platelet activation and thus may predict thrombotic events. The goal of this study was to investigate the association of the mean platelet volume and the major adverse events after coronary artery bypass surgery.

Methods

Baseline clinical details and preoperative hematologic parameters were obtained prospectively in 205 consecutive patients undergoing coronary artery bypass surgery. Postoperative mortality and major adverse events were recorded in the early postoperative period (median of 72 days, interquartile range 58.5-109 days).

Results

Combined adverse events occurred in 37 patients (18.0%) during the early follow-up. The preoperative mean platelet volume and hematocrit levels were found to be associated with postoperative adverse events (p<0.001 for both variables). In multivariate logistic regression models, the preoperative mean platelet volume and hematocrit levels were strong independent predictors of combined adverse events after surgery (respectively OR 1.89, p=0.037; OR 0.87, p=0.011). After receiver-operating-characteristics curve analysis, using a cut-point of 8.75 fL, the preoperative mean platelet volume level predicted adverse events with a sensitivity of 54% and specificity of 70%. In a further model with cut-off points, higher preoperative mean platelet volume levels remained a powerful independent predictor of postoperative myocardial infarction (OR 3.60, p=0.013) and major adverse cardiac events (OR 2.53, p=0.045).

Conclusions

An elevated preoperative mean platelet volume is associated with an adverse outcome after coronary artery bypass grafting. In conclusion, we can say that mean platelet volume is an important, simple, readily available, and cost effective tool and can be useful in predicting the postoperative adverse events in patients undergoing coronary artery bypass grafting.

Predictors of transfusion of packed red blood cells in coronary artery bypass grafting surgery

OBJECTIVES

Finding predictors of blood transfusion may facilitate the most efficient approach for the use of blood bank services in coronary artery bypass grafting procedures. The aim of this retrospective study is to identify preoperative and intraoperative patient characteristics predicting the need for blood transfusion during or after CABG in our local cardiac surgical service.

METHODS

435 patients undergoing isolated first-time CABG were reviewed for their preoperative and intraoperative variables and analyzed postoperative data. Patients were 255 males and 180 females, with mean age 62.01 ± 10.13 years. Regression logistic analysis was used for identifying the strongest perioperative predictors of blood transfusion.

RESULTS

Blood transfusion was used in 263 patients (60.5%). The mean number of transfused blood products units per patient was 2.27 ± 3.07 (0-23) units. The total number of transfused units of blood products was 983. Univariate analysis identified age >65 years, weight <70 Kg, body mass index <25 Kg/m2, hemoglobin <13mg/dL, hematocrit < 40% and ejection fraction <50%, use of cardiopulmonary bypass (CPB), not using an internal thoracic artery as a bypass, and multiple bypasses as significant predictors. The strongest predictors using multivariate analysis were hematocrit < 40% (OR 2.58; CI 1.62-4.15; P<0.001), CPB use (OR 2.00; CI 1.27-3.17; P=0.003) and multiple bypasses (OR 2.31; CI 1.31-4.08; P=0.036).

CONCLUSIONS

The identification of these risk factors leads to better identification of patients with a greater probability of using blood, allocation blood bank resources and cost-effectiveness use of blood products.

Use of blood products and risk of stroke after coronary artery bypass surgery

BACKGROUND

The impact of blood transfusion on the development of post-operative stroke after coronary artery bypass grafting (CABG) is not well established. We, therefore, investigated this issue.

MATERIALS AND METHODS

Complete data on peri-operative blood transfusion were available for 2,226 patients who underwent CABG in three Finnish hospitals.

RESULTS

Stroke occurred post-operatively in 53 patients (2.4%). Logistic regression showed that pre-operative creatinine (OR 1.003, 95% CI 1.000-1.006), extracardiac arteriopathy (OR 2.344, 95% CI 1.133-4.847), pre-operative atrial fibrillation (OR 2.409, 95% CI 1.149-5.052), and the number of packed red blood cell units transfused (OR 1.121, 95% CI 1.065-1.180) were significantly associated with post-operative stroke. When the various blood product transfusions instead of transfused units were included in the multivariable analysis, solvent/detergent treated plasma (Octaplas) transfusion (OR 2.149, 95% CI 1.141-4.047), but not red blood cell transfusion, was significantly associated with postoperative stroke. Use of blood products ranging from no transfusion (stroke rate 1.6%) to combined transfusion of red blood cells, platelets and Octaplas was associated with a significant increase in post-operative stroke incidence (6.6%, adjusted analysis: OR 1.727, 95% 1.350-2.209). Patients who received >2 units of red blood cells, >4 units of Octaplas units and >8 units of platelets had the highest stroke rate of 21%. CART analysis showed that increasing amount of transfused Octaplas, platelets and history of extracardiac arteriopathy were significantly associated with post-operative stroke.

CONCLUSIONS

Transfusion of blood products after CABG has a strong, dose-dependent association with the risk of stroke. The use of Octaplas and platelet transfusions seem to have an even larger impact on the development of stroke than red blood cell transfusions.

Blood transfusion after cardiac surgery: is it the patient or the transfusion that carries the risk?

BACKGROUND

The transfusion of red blood cells (RBCs) after cardiac surgery has been associated with increased long-term mortality. This study reexamines this hypothesis by including pre-operative hemoglobin (Hb) levels and renal function in the analysis.

METHODS

A retrospective single-center study was performed including 5261 coronary artery bypass grafting (CABG) patients in a Cox proportional hazard survival analysis. Patients with more than eight RBC transfusions, early death (7 days), and emergent cases were excluded. Patients were followed for 7.5 years. Previously known risk factors were entered into the analysis together with pre-operative Hb and estimated glomerular filtration rate (eGFR). In addition, subgroups were formed based on the patients' pre-operative renal function and Hb levels.

RESULTS

When classical risk factors were entered into the analysis, transfusion of RBCs was associated with reduced long-term survival. When pre-operative eGFR and Hb was entered into the analysis, however, transfusion of RBCs did not affect survival significantly. In the subgroups, transfusion of RBCs did not have any effect on long-term survival.

CONCLUSIONS

When pre-operative Hb levels and renal function are taken into account, moderate transfusions of RBC after CABG surgery do not seem to be associated with reduced long-term survival.

Intraoperative hemoglobin levels and transfusion independently predict stroke after cardiac operations

BACKGROUND

Anemia has been associated with adverse cerebrovascular outcomes, particularly after cardiac operations. This study was conducted to determine if hemoglobin levels during and after cardiopulmonary bypass (CPB) predict postoperative stroke in cardiac surgical patients, independent of transfusion requirements.

METHODS

Individuals who had sustained a clinical postoperative stroke (cases) were matched 1:2 with controls by age, sex, surgical procedure, and year of operation. In 617 patients, conditional logistic regression was performed to analyze associations between hemoglobin levels before and after CPB, and stroke.

RESULTS

After adjustment for potentially confounding vascular risk factors, lower hemoglobin after CPB was associated with a higher risk of stroke, even after adjustment for the amount of packed red blood cells transfused (adjusted odds ratio, 1.28; 95% confidence interval, 1.00 to 1.64, per point of lower hemoglobin level; adjusted odds ratio for stroke per higher quartile of packed red blood cells transfused in this model, 1.37; 95% confidence interval, 1.02 to 1.83). Similar associations were not found for hemoglobin concentrations preoperatively nor change in hemoglobin from before to after CPB. A post-CPB hemoglobin level below the median was associated with 37% increased odds of a postoperative stroke occurring (p = 0.02).

CONCLUSIONS

Lower postoperative hemoglobin levels and higher intraoperative transfusion requirements are each independently associated with a higher risk of stroke. Reduced cerebral oxygen delivery due to anemia may contribute to cerebral injury after coronary artery bypass grafting.

A multidisciplinary "think tank": the top 10 clinical trial opportunities in transfusion medicine from the National Heart, Lung, and Blood Institute-sponsored 2009 state-of-the-science symposium

BACKGROUND

In September 2009, the National Heart, Lung, and Blood Institute convened the State-of-the-Science Symposium in Transfusion Medicine to identify Phase II and/or III clinical trials that would provide important information to advance transfusion medicine.

STUDY DESIGN AND METHODS

Seven multidisciplinary subcommittees developed proposals in the following areas: 1) platelet (PLT) product use, 2) neonatal and/or pediatric transfusion practice, 3) surgical transfusion practice, 4) intensive care unit and/or in trauma transfusion practice, 5) plasma and/or cryoprecipitate product use and therapeutic apheresis practice, 6) red blood cell (RBC) product use and/or blood conservation management, and 7) medical transfusion practice or blood donor studies. The committees consisted of transfusion medicine specialists, hematologists, cardiovascular surgeons, anesthesiologists, neonatologists, critical care physicians, and clinical trial methodologists. Proposals were presented and an external panel evaluated and prioritized each concept for scientific merit, clinical importance, and feasibility.

RESULTS

Twenty-four concepts were presented by the subcommittees. Ten concepts addressed four areas deemed most important: 1) PLT transfusion strategies to prevent and/or mitigate bleeding in neonates and patients with hematologic malignancies, 2) RBC transfusion trigger strategies to improve overall outcomes in different patient populations, 3) evaluation of optimal plasma:PLT:RBC ratios in trauma resuscitation, and 4) pathogen inactivation of PLTs to improve PLT transfusion safety.

CONCLUSIONS

The proposal themes not only represent inquiries about the indications for transfusion, but also epitomize the lack of consensus when clinical practice lacks a strong evidence base. Ultimately, the purpose of this publication is to provide a "blueprint" of ideas for further development rather than endorse any one specific clinical trial design.

Preoperative anemia associated in-hospital mortality and morbidity in isolated coronary artery bypass graft surgery

Anemia is an indisputable finding in patients scheduled for coronary artery bypass graft (CABG) that can occur any time preoperatively. In presence of severe coronary artery disease, anemia can dramatically affect surgical outcomes. Therefore, we conducted this study to determine the effect of low preoperative hemoglobin (Hgb) on postoperative outcome in patients who underwent coronary artery bypass graft (CABG). In all, 4432 patients who had undergone isolated CABG at Tehran Heart Center over the 2-year period from March 2006 to February 2008 were studied. All medical records of the aforementioned patients were derived from our hospital surgery data bank. After adjustment for confounders, the association of different preoperative levels of Hgb with risk of cardiac, pulmonary, infectious, and ischemic complications, and also with prolonged ventilation and resource utilization, were assessed in a multivariable model. After adjustment for confounders that may affect mortality and morbidities, we found that cardiac, infectious, ischemic, and pulmonary complications, as well as postoperative mortality, were significantly higher in anemic patients compared to those with normal Hgb levels. In addition, total ventilation time, total intensive care unit hour stay (ICU), hospital length of stay (HLOS), and postsurgery length of stay (PLOS) were significantly longer in anemic patients. We concluded that isolated CABG patients with preoperative anemia have significantly higher mortality and morbidity, and use more health care resources. Preoperative anemia is an independent variable for increased resource utilization, morbidity, and mortality.

Preoperative hemoglobin level as a predictor of survival after coronary artery bypass grafting: a comparison with the matched general population

BACKGROUND

The predictive value of the preoperative hemoglobin value after coronary artery bypass grafting (CABG) has not been well established. We studied how the preoperative hemoglobin level affects the survival of patients after CABG. Late mortality was compared with that of a general population.

METHODS AND RESULTS

Early and late mortality of all consecutive patients undergoing isolated CABG between January 1998 and December 2007 were determined. Patients were classified into 4 groups stratified by preoperative hemoglobin level. The cutoff point for anemia was 13 g/dL for men and 12 g/dL for women. Expected survival of a matched general Dutch population cohort was obtained from the database of the Dutch Central Bureau for Statistics. After the exclusion of 122 patients who were lost to follow-up and 481 patients with missing preoperative hemoglobin levels, complete data were obtained in 10,025 patients. Multivariate logistic regression analyses revealed anemia to be an independent risk factor for higher early mortality. Cox regression analyses revealed low hemoglobin level, both as a continuous variable and as a dichotomous variable (anemia), to be a predictor of higher late mortality. Compared with expected survival, patients with the lowest preoperative hemoglobin levels had a worse outcome, whereas patients with the highest hemoglobin levels had a better outcome.

CONCLUSIONS

A lower preoperative hemoglobin level is an independent predictor of late mortality in patients undergoing CABG, whereas anemia is a risk factor for early and late mortality. Compared with the general population, anemic patients had worse survival than expected, whereas nonanemic patients had better survival than expected.

Anemia and red blood cell transfusion in neurocritical care

INTRODUCTION

Anemia is one of the most common medical complications to be encountered in critically ill patients. Based on the results of clinical trials, transfusion practices across the world have generally become more restrictive. However, because reduced oxygen delivery contributes to 'secondary' cerebral injury, anemia may not be as well tolerated among neurocritical care patients.

METHODS

The first portion of this paper is a narrative review of the physiologic implications of anemia, hemodilution, and transfusion in the setting of brain-injury and stroke. The second portion is a systematic review to identify studies assessing the association between anemia or the use of red blood cell transfusions and relevant clinical outcomes in various neurocritical care populations.

RESULTS

There have been no randomized controlled trials that have adequately assessed optimal transfusion thresholds specifically among brain-injured patients. The importance of ischemia and the implications of anemia are not necessarily the same for all neurocritical care conditions. Nevertheless, there exists an extensive body of experimental work, as well as human observational and physiologic studies, which have advanced knowledge in this area and provide some guidance to clinicians. Lower hemoglobin concentrations are consistently associated with worse physiologic parameters and clinical outcomes; however, this relationship may not be altered by more aggressive use of red blood cell transfusions.

CONCLUSIONS

Although hemoglobin concentrations as low as 7 g/dl are well tolerated in most critical care patients, such a severe degree of anemia could be harmful in brain-injured patients. Randomized controlled trials of different transfusion thresholds, specifically in neurocritical care settings, are required. The impact of the duration of blood storage on the neurologic implications of transfusion also requires further investigation.