Can the EuroSCORE predict the early and mid-term mortality after off-pump coronary artery bypass grafting?

Institutional case-volume-incorporated mortality risk prediction model after cardiac surgery

BACKGROUND

Most risk prediction models predicting short-term mortality after cardiac surgery incorporate patient characteristics, laboratory data, and type of surgery, but do not account for surgical experience. Considering the impact of case volume on patient outcome after high-risk procedures, we attempted to develop a risk prediction model for mortality after cardiac surgery that incorporates institutional case volume.

METHODS

Adult patients who underwent cardiac surgery from 2009 to 2016 were identified. Patients who underwent cardiac surgery (n = 57,804) were randomly divided into the derivation cohort (n = 28,902) or the validation cohorts (n = 28,902). A risk prediction model for in-hospital mortality and 1-year mortality was developed from the derivation cohort and the performance of the model was evaluated in the validation cohort.

RESULTS

The model demonstrated fair discrimination (c-statistics, 0.76 for in-hospital mortality in both cohorts; 0.74 for 1-year mortality in both cohorts) and acceptable calibration. Hospitals were classified based on case volume into 50 or less, 50-100, 100-200, or more than 200 average cardiac surgery cases per year and case volume was a significant variable in the prediction model.

CONCLUSIONS

A new risk prediction model that incorporates institutional case volume and accurately predicts in-hospital and 1-year mortality after cardiac surgery was developed and validated.

Impact of preoperative nutritional scores on 1-year postoperative mortality in patients undergoing valvular heart surgery

OBJECTIVE

Malnutrition is a well-recognized risk factor for poor prognosis and mortality. We investigated whether preoperative malnutrition diagnosed with objective nutritional scores affects 1-year mortality in patients undergoing valvular heart surgery.

METHODS

In this retrospective cohort observational study, we evaluated the association among the Controlling Nutritional Status score, Prognostic Nutritional Index, and Geriatric Nutritional Risk Index with 1-year mortality in 1927 patients undergoing valvular heart surgery. We identified factors for mortality using multivariable Cox proportional hazard analysis and investigated the utility of nutritional scores for risk stratification.

RESULTS

Malnutrition, as identified by a high Controlling Nutritional Status score and low Prognostic Nutritional Index and Geriatric Nutritional Risk Index, was significantly associated with higher 1-year mortality. Kaplan-Meier survival curve showed that mortality significantly increased as the severity of malnutrition increased (log-rank test, P < .001). The predicted discrimination (C-index) was 0.79 with the Controlling Nutritional Status score, 0.77 with the Prognostic Nutritional Index, and 0.73 with the Geriatric Nutritional Risk Index. Each nutritional index (Controlling Nutritional Status; hazard ratio, 1.31, 95% confidence interval, 1.21-1.42, P < .001), the European System for Cardiac Operative Risk Evaluation II (hazard ratio, 1.07, 95% confidence interval, 1.04-1.09, P < .001), and chronic kidney disease (hazard ratio, 2.26, 95% confidence interval, 1.31-3.90, P = .003) were independent risk factors for mortality. The Controlling Nutritional Status score added to the European System for Cardiac Operative Risk Evaluation II significantly increased the predictive discrimination ability for mortality (C-index 0.82, 95% confidence interval, 0.78-0.87, P = .014) compared with the Controlling Nutritional Status or European System for Cardiac Operative Risk Evaluation II alone.

CONCLUSIONS

Preoperative malnutrition as assessed by objective nutritional scores was associated with 1-year mortality after valvular heart surgery. The Controlling Nutritional Status score had the highest predictive ability and, when added to the European System for Cardiac Operative Risk Evaluation II, provided more accurate risk stratification.

Performance of EuroSCORE II and logistic EuroSCORE in Bangladeshi population undergoing off-pump coronary artery bypass surgery: A prospective cohort study

Introduction

European System for Cardiac Operative Risk Evaluation (EuroSCORE) was developed to identify patients who may have a greater postoperative risk for adverse effects following adult cardiac surgery. This study evaluated the discriminatory potential of using the EuroSCORE system in predicting the early, as well as late, postoperative outcomes following coronary artery bypass graft surgery in Bangladesh.

Methods

A total of 865 patients who underwent isolated coronary artery bypass graft surgery were evaluated with the EuroSCORE risk scoring system. Moreover, we also compared the discriminatory potentials between the EuroSCORE II and the original logistic EuroSCORE.

Results

Operative mortality was best predicted by EuroSCORE II (area under the curve (AUC) 0.863, Brier score 0.030) compared to the original logistic EuroSCORE (AUC 0.849, Brier score 0.033). However, the overall expected-to-observed mortality ratio for EuroSCORE II was 1.1, whereas the observed ratio for the original logistic EuroSCORE was 1.7. EuroSCORE II was predictive of an intensive care unit stay of five days or more (AUC 0.786), prolonged inotropes use (AUC 0.746), stroke (AUC 0.646), de novo dialysis (AUC 0.810), and low output syndrome (AUC 0.715). Moreover, a high EuroSCORE II quintile significantly predicted the risk for late mortality (p < 0.0001).

Conclusions

EuroSCORE has an important role in predicting the early, as well as late, postoperative outcomes following coronary artery bypass surgery. However, the performance of EuroSCORE II is significantly better than the original logistic EuroSCORE in predicting postoperative morbidity and mortality after isolated coronary artery bypass graft surgery among Bangladeshi patients.

EuroSCORE II with SYNTAX score to assess risks of coronary artery bypass grafting outcomes

OBJECTIVES

We evaluated the usefulness of the combination of European System for Cardiac Operative Risk Evaluation score (EuroSCORE II) and SYNergy between percutaneous intervention with TAXus drug-eluting stents and cardiac surgery (SYNTAX) score in predicting risks associated with early and late outcomes after coronary artery bypass grafting (CABG).

METHODS

Between January 2010 and April 2012, 412 patients underwent isolated CABG at our institution. EuroSCORE II and SYNTAX score were calculated retrospectively, and their ability to predict early and long-term outcomes was evaluated. Patients were divided into four groups according to median EuroSCORE II and SYNTAX score: Group 1, low EuroSCORE II, low SYNTAX (n=103); Group 2, low EuroSCORE II, high SYNTAX (n=103); Group 3, high EuroSCORE II, low SYNTAX (n=99); and Group 4, high EuroSCORE II, high SYNTAX (n=107).

RESULTS

Operative death was not different among the groups; however, Group 4 had the highest major complication rate of the four groups (0 in Group 1, 2.9% in Group 2, 3.0% in Group 3 and 8.4% in Group 4; P=0.011). Multivariate analyses revealed that both high EuroSCORE II (odds ratio [OR]: 4.154; P=0.030) and high SYNTAX score (OR: 3.988; P=0.035) were independent predictors of postoperative major complications and that high EuroSCORE II was an independent predictor of late mortality (OR: 4.673; P=0.016) but high SYNTAX score was not (OR: 0.808; P=0.662). Actuarial survival rate at 3 years was the lowest in Group 4 (99.0±1.0% in Group 1, 97.7±1.6% in Group 2, 91.9±2.7% in Group 3 and 90.5±4.7% in Group 4; P=0.045).

CONCLUSIONS

The combination of EuroSCORE II and SYNTAX score was useful in predicting early major complications after CABG. In the long term, EuroSCORE II continued to be associated with late mortality, but SYNTAX score did not.

Two new mathematical models for prediction of early mortality risk in coronary artery bypass graft surgery

OBJECTIVES

The aim of this study was to develop new models for prediction of short-term mortality risk in on-pump coronary artery bypass grafting (CABG) surgery using decision tree (DT) methods.

METHODS

Between September 2005 and April 2006, 948 consecutive patients underwent CABG surgery at Rajaie Heart Center. Potential risk factors were reviewed and univariate and multivariate analysis for short-term mortality were performed. The whole dataset was divided into mutually exclusive subsets. An entropy error fuzzy decision tree (EEFDT) and an entropy error crisp decision tree (EECDT) were implemented using 650 (68.6%) patient data and tested with 298 (31.4%) patient data. Ten times hold-out cross validation was done and the area under the receiver operative characteristic curve (AUC) was reported as model performance. The results were compared with the logistic regression (LR) model and EuroSCORE.

RESULTS

The overall short-term mortality rate was 3.8%, and was statistically higher in women than men (P<.001). The final EEFDT selected 19 variables and resulted in a tree with 39 nodes, 20 conditional rules, and AUC of 0.90±0.008. The final EECDT selected 15 variables and resulted in a tree with 35 nodes, 18 conditional rules, and AUC of 0.86±0.008. The LR model selected 10 variables and resulted in an AUC of 0.78±0.008; the AUC for EuroSCORE was 0.77±0.003. There were no differences in the discriminatory power of EEFDT and EECDT (P=.066) and their performance was superior to LR and EuroSCORE.

CONCLUSIONS

EEFDT, EECDT, LR, and EuroSCORE had clinical acceptance but the performance and accuracy of the DTs were superior to the other models.

Performance of the original EuroSCORE

The European system for cardiac operative risk evaluation (EuroSCORE) is a commonly used risk score for operative mortality following cardiac surgery. We aimed to conduct a systematic review of the performance of the additive and logistic EuroSCORE. A literature search resulted in 67 articles. Studies applying the EuroSCORE on patients undergoing cardiac surgery and which reported early mortality were included. Weighted meta-regression showed that the EuroSCORE overestimated mortality. However, this performance depended on the risk profile of patients: in high-risk patients, the additive model actually underestimated mortality. Discriminative performance was good. Given the poor predictive performance, the EuroSCORE may not be suitable as a tool for patient selection nor for benchmarking.

Impact of High-Dose Statin Pretreatment in Patients with Stable Angina during Off-Pump Coronary Artery Bypass

BACKGROUND

Periprocedural treatment with high-dose statins is known to have cardioprotective and pleiotropic effects, such as anti-thrombotic and anti-inflammatory actions. We aimed to assess the efficacy of high-dose rosuvastatin loading in patients with stable angina undergoing off-pump coronary artery bypass grafting (OPCAB).

MATERIALS AND METHODS

A total of 142 patients with stable angina who were scheduled to undergo surgical myocardial revascularization were randomized to receive either pre-treatment with 60-mg rosuvastatin (rosuvastatin group, n=71) or no pre-treatment (control group, n=71) before OPCAB. The primary endpoint was the 30-day incidence of major adverse cardiac events (MACEs). The secondary endpoint was the change in the degree of myocardial ischemia as evaluated with creatine kinase-myocardial band (CK-MB) and troponin T (TnT).

RESULTS

There were no significant intergroup differences in preoperative risk factors or operative strategy. MACEs within 30 days after OPCAB occurred in one patient (1.4%) in the rosuvastatin group and four patients (5.6%) in the control group, respectively (p=0.37). Preoperative CK-MB and TnT were not different between the groups. After OPCAB, the mean maximum CK-MB was significantly higher in the control group (rosuvastatin group 10.7±9.75 ng/mL, control group 14.6±12.9 ng/mL, p=0.04). Furthermore, the mean levels of maximum TnT were significantly higher in the control group (rosuvastatin group 0.18±0.16 ng/mL, control group 0.39±0.70 ng/mL, p=0.02).

CONCLUSION

Our findings suggest that high-dose rosuvastatin loading before OPCAB surgery did not result in a significant reduction of 30-day MACEs. However, high-dose rosuvastatin reduced myocardial ischemia after OPCAB.

Outcome evaluation of coronary artery bypass grafting surgery applying the EuroSCORE in a Caribbean developing country

BACKGROUND

The risk-adjusted outcome of coronary artery bypass grafting (CABG) in Trinidad and Tobago was evaluated by applying the EuroSCORE scoring system.

METHODS

A retrospective study was undertaken by reviewing the case notes of patients who underwent CABG from 2003 to 2008 under Caribbean Heart Care. Data collected included age, sex, smoking status, comorbidities, chronic pulmonary disease, extracardiac arteriopathy, neurologic disease, previous cardiac surgery, serum creatinine, active endocarditis, critical preoperative state, and mode of surgery. Predicted mortality was calculated with the EuroSCORE, the model was calibrated by Hosmer-Lemeshow analysis, and the discriminant function was analyzed by using the receiver operating characteristic (ROC) curve.

RESULTS

We studied 1082 patients who underwent CABG, 75.6% of whom were of Asian Indian ethnicity. The overall mean (±SD) EuroSCORE was 2.87 ± 2.1. The predicted perioperative mortality rate was 2.3%, and the observed mortality rate was 1.2%. The overall standardized mortality ratio was 0.52. Eighty-six percent of the patients underwent off-pump CABG. Hosmer-Lemeshow analysis showed that the system calibrated well to our case mix (Hosmer-Lemeshow value, 6.87; degrees of freedom, 8; P = .551). The EuroSCORE discriminated patient outcomes well, as shown by the area under the ROC curve (0.78). Age and ethnicity did not influence the outcome.

CONCLUSIONS

The outcomes of CABG surgery patients are good in Trinidad and Tobago and are comparable to standards in developed countries when evaluated with the EuroSCORE. The proportion of patients undergoing off-pump CABG is high.

Cost-effectiveness of clinical pathway in coronary artery bypass surgery

Few studies have been devoted to the exploration of the effect of clinical pathways on coronary artery diseases treated with coronary artery bypass (CAB) surgery. This study was aimed to investigate the cost and effectiveness of the clinical pathway on CAB surgery in a medical center. With a retrospective dataset in 2003-2007, 212 CAB surgery patients were included. Data of the costs and postoperative complication occurrence and length of stays were the focus and patient demographics, surgical risk indicator EuroSCORE, surgical conditions were collected. It revealed that there was differentiation across specified cost items in beating heart CAB surgery patients, but not for heart arrest CAB surgery patients with and without clinical pathways enrolled. In addition, there was no difference in postoperative complication occurrence in CAB surgery patients enrolled into clinical pathways. However, robotic beating heart CAB surgery patients enrolled clinical pathways were shown to have less postoperative ordinary ward stay than those not enrolled clinical pathways. CAB surgery patients' age and surgical risks were related to their postoperative lengths of stay to some extent.

Risk stratification models for cardiac surgery

A wide variety of risk stratification systems have been developed to quantify the risk of cardiac surgery. Generally, the focus has been on mortality; however, more recently models have been developed that allow the preoperative prediction of the incidence of morbidity, including renal failure, infection, prolonged ventilation, and neurologic deficit. Many of these risk stratification models are developed from large databases of cardiac surgical patients. Patient and surgical factors that are present preoperatively are assessed for their predictive value for postoperative complications. Risk factors that are found to be significant are assigned a specific weight in the overall summation of risk. These models have been used as tools to compare surgeon's results, institutional outcomes, individual patient risk, and within quality improvement programs. This article will focus on the European System for Cardiac Operative Risk Evaluation, the Society of Thoracic Surgeons score, the Parsonnet score, Cleveland Clinic Model, the Bayes model, and the Northern New England Score.

Performance of EuroSCORE in CABG and off-pump coronary artery bypass grafting: single institution experience and meta-analysis

AIMS

To assess EuroSCORE performance in predicting in-hospital mortality in on-pump coronary artery bypass grafting (CABG) and off-pump coronary artery bypass grafting (OPCAB).

METHODS AND RESULTS

Additive and logistic EuroSCORE were computed for consecutive patients undergoing CABG (n = 3440, 75%) or OPCAB (n = 1140, 25%) at our hospital from 1999 to September 2007. The areas under the receiver operating characteristic (ROC) curves (AUCs) were used to describe performance and accuracy. No difference in performance between CABG and OPCAB and between additive and logistic EuroSCORE (additive EuroSCORE AUCs of 0.808 and 0.779 for CABG and OPCAB, respectively; logistic EuroSCORE AUCs of 0.813 and of 0.773 for CABG and OPCAB, respectively) was found, although a marked tendency to overpredict mortality by both models was evident. A meta-analysis of previously published data was done, and a total of eight studies representing 19 212 and 5461 patients undergoing CABG and OPCAB, respectively, met inclusion criteria. Meta-analysis confirmed similar performance of EuroSCORE in CABG and OPCAB: estimated AUCs were 0.767 and 0.766 for CABG and OPCAB, respectively, with an estimated difference of 0.001 (95% CI -0.061 to 0.063).

CONCLUSION

Additive and logistic EuroSCORE algorithms performed similarly, and cumulative evidence suggests comparable performance in CABG and OPCAB procedures; both risk models, however, significantly overestimated mortality.