EuroSCORE overestimates the cardiac operative risk

Systematic review and meta-analysis of mortality risk prediction models in adult cardiac surgery

OBJECTIVES

The most used mortality risk prediction models in cardiac surgery are the European System for Cardiac Operative Risk Evaluation (ES) and Society of Thoracic Surgeons (STS) score. There is no agreement on which score should be considered more accurate nor which score should be utilized in each population subgroup. We sought to provide a thorough quantitative assessment of these 2 models.

METHODS

We performed a systematic literature review and captured information on discrimination, as quantified by the area under the receiver operator curve (AUC), and calibration, as quantified by the ratio of observed-to-expected mortality (O:E). We performed random effects meta-analysis of the performance of the individual models as well as pairwise comparisons and subgroup analysis by procedure type, time and continent.

RESULTS

The ES2 {AUC 0.783 [95% confidence interval (CI) 0.765–0.800]; O:E 1.102 (95% CI 0.943–1.289)} and STS [AUC 0.757 (95% CI 0.727–0.785); O:E 1.111 (95% CI 0.853–1.447)] showed good overall discrimination and calibration. There was no significant difference in the discrimination of the 2 models (difference in AUC −0.016; 95% CI −0.034 to −0.002; P = 0.09). However, the calibration of ES2 showed significant geographical variations (P < 0.001) and a trend towards miscalibration with time (P=0.057). This was not seen with STS.

CONCLUSIONS

ES2 and STS are reliable predictors of short-term mortality following adult cardiac surgery in the populations from which they were derived. STS may have broader applications when comparing outcomes across continents as compared to ES2.

REGISTRATION

Prospero (https://www.crd.york.ac.uk/PROSPERO/) CRD42020220983.

The Effect of Preoperative Hematocrit Level on Early Outcomes After Coronary Artery Bypass Surgery

INTRODUCTION

Low hematocrit level is a hematological problem that is frequently encountered in the preoperative evaluation of patients undergoing coronary artery bypass grafting (CABG) surgery. The aim of this study was to investigate the effect of preoperative hematocrit level on the first 30-day outcomes in patients undergoing CABG surgery.

METHODS

Ninety-four patients undergoing isolated CABG were included in the study. The patients were divided into two groups as patients with preoperative low hematocrit levels (<36%) in Group 1 and patients with preoperative normal hematocrit levels (≥36%) in Group 2.

RESULTS

Forty-six patients in Group 1 (mean age: 63.6 ± 7.9 years) and 48 patients in Group 2 (mean age: 56.5 ± 8.8 years) were enrolled. European System for Cardiac Operative Risk Evaluation (EuroSCORE) scoring was statistically significantly higher in Group 1 (p = 0.011). In the postoperative period, the amount of drainage, transfusion of blood, and blood products were significantly higher in Group 1 (p < 0.001). The mortality rate of Group 1 was statistically higher in the first 30 days postoperatively (p = 0.020).

CONCLUSION

Low preoperative hematocrit levels are associated with increased mortality after CABG surgery. We suggest that patients' preoperative hematocrit levels must be added to the risk scoring systems as an assessment parameter.

Right mini-thoracotomy approach reduces hospital stay and transfusion of mitral or tricuspid valve reoperation with non-inferior efficacy: evidence from propensity-matched study

Background

There is limited evidence about the efficacy and cost difference between minimally invasive and conventional valve reoperation. This study intended to compare the short-term efficacy and cost between right mini-thoracotomy approach and median sternotomy approach in valve reoperation.

Methods

From Feb 2011 to Sep 2017, 156 patients underwent valve reoperation including 68 cases of minimally invasive approach and 88 cases of traditional median sternotomy approach in our hospital. A propensity scoring was used to match patients with similar demographic characteristics. A total of 42 pairs of patients were left and divided into the conventional sternotomy group (CS group) and the right mini-thoracotomy group (RT group). A retrospective study of efficacy and cost was conducted between two groups.

Results

There was no statistical difference between two groups in demographical characteristics after propensity-scoring match (P>0.05). In-hospital mortality was 11.9% (5/42) for CS group and 7.1% (3/42) for the RT group (P=0.687). No significant disparity was found in the incidence of complications between two groups (P>0.05). CPB time (P=0.012), bypass time (P=0.006) and operation time (P=0.003) of CS group were significantly higher than RT group. Blood loss (P=0.014) and transfusion volume (P=0.003) of RT group was less than CS group. Shorter ICU and hospital stay was seen in RT group compared with CS group (P<0.001). Though the materials cost of RT group was higher than CS group (P<0.001), no significant disparity was found in total cost between CS group and RT group (P=0.790).

Conclusions

The right mini-thoracotomy approach can achieve equivalent efficacy with conventional median approach, and doesn't necessarily increase the total cost. Moreover, the minimally invasive approach can decrease the operation time, hospital stay and blood product transfusion.

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.

Mortality from isolated coronary bypass surgery: a comparison of the Society of Thoracic Surgeons and the EuroSCORE risk prediction algorithms

We compared the performances of the additive European System for Cardiac Operative Risk Evaluation, EuroSCORE (AES) and logistic EuroSCORE (LES) with the Society of Thoracic Surgeons' risk prediction algorithm in terms of discrimination and calibration in predicting mortality in patients undergoing isolated coronary artery bypass grafting (CABG) at a single institution in Pakistan. Both models were applied to 380 patients, operated upon at the Aga Khan University Hospital from August 2009 to July 2010. The actual mortality was 2.89%. The mean AES of all patients was 4.36 ± 3.58%, the mean LES was 5.96 ± 9.18% and the mean Society of Thoracic Surgeons' (STS) score was 2.30 ± 4.16%. The Hosmer-Lemeshow goodness-of-fit test gave a P-value of 0.801 for AES, 0.699 for LES and 0.981 for STS. The area under the receiver operating characteristic curve was 0.866 for AES, 0.842 for LES and 0.899 for STS. STS outperformed AES and LES both in terms of calibration and discrimination. STS, however, underestimated mortality in the top 20% of patients having an STS score >2.88, thus overall STS estimates were lower than actual mortality. We conclude that STS is a more accurate model for risk assessment as compared to additive and logistic EuroSCORE models in the Pakistani population.

[Evaluation of results in coronary surgery using EuroSCORE]

INTRODUCTION

The European System for Cardiac Operative Risk Evaluation (EuroSCORE) was developed in order to predict operative risk in cardiac surgery and to assess the quality of the cardio-surgical care. Introduction of the uniform terminology in result evaluation process leads to the significant improvement in measuring and evaluation of surgical treatment quality.

OBJECTIVE

The aim of the study was to evaluate our results in isolated coronary surgery using the EuroSCORE.

METHODS

The study was done respectively by analysing predicted mortality according to the EuroSCORE model and observed operative risk in 4,675 coronary patients operated at our Clinic during the period 2001-2008. For statistical analyses, the Pearson, Chi-square and ANOVA tests were used.

RESULTS

The total postoperative mortality predicted by the EuroSCORE was 2.9 +/- 2.25, while the observed one was 2.2%. When the scoring system and observed results were compared over the years, a considerably lower observed mortality was found during the last 4 years. Overall average number of distal anastomoses was 2.62 +/- 0.84. During the period 2004-2008, the average number of coronary anastomoses increased over the years reaching the value of 2.77 +/- 0.88. The difference is at the level of statistical significance with the trend of further increase. Percentage of the patients with single or double graft myocardial revascularization decreases, while the number of the patients with triple or more bypasses increases.

CONCLUSION

During the last years, the results in isolated coronary surgery have considerably improved. The EuroSCORE overestimates operative risk. In order to improve its predictive value, the model should be recalibrated.

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.

Early mortality from off-pump and on-pump coronary bypass surgery in Canada: a comparison of the STS and the EuroSCORE risk prediction algorithms

OBJECTIVE

Early mortality from off-pump and on-pump coronary artery bypass graft (CABG) surgery was assessed and compared with two widely used risk algorithms for CABG: The Society of Thoracic Surgeons (STS) and the European System for Cardiac Operative Risk Evaluation (EuroSCORE).

METHOD

From March 12, 2001, to December 31, 2002, 1657 consecutive patients were treated with off-pump CABG and 1693 consecutive patients were treated with on-pump CABG. The predicted risk of mortality scores for the STS and EuroSCORE models were calculated. The predictive accuracy for early mortality was assessed by comparing the observed and expected mortalities for equal-sized quantiles of risk using the Hosmer-Lemeshow goodness-of-fit test. The discriminatory power of the models was evaluated by calculating the area under the receiver operating characteristic (ROC) curves.

RESULTS

The observed postoperative mortality was 1.8% (95% CI 1.3% to 2.4%) for off-pump CABG and 1.5% (95% CI 1.1% to 2.1%) for on-pump CABG. For both on-pump and off-pump CABG surgery, the Hosmer-Lemeshow goodness-of-fit test indicated good accuracy. The area under the ROC curve was 0.81 (95% CI 0.73 to 0.90) for the STS and 0.79 (95% CI 0.71 to 0.88) for EuroSCORE in off-pump CABG (P=0.567). The area under the ROC curve was 0.82 (95% CI 0.73 to 0.91) for STS and 0.81 (95% CI 0.71 to 0.90) for EuroSCORE in on-pump CABG (P=0.616). The STS-predicted risk of stroke, prolonged ventilation and renal failure were similar to the observed data, with relatively good discriminatory powers for both off-pump and on-pump CABG.

CONCLUSION

Both the STS and EuroSCORE risk algorithms are good predictors of early mortality from off-pump or on-pump CABG surgery. However, the generalizability of these results in the Canadian context would require a broader sampling of Canadian centres, including ones that provide both on-pump and off-pump CABG.

Valor predictivo del modelo EuroSCORE en la cirugía cardíaca de nuestro centro

OBJECTIVE

The use of risk prediction models in cardiac surgery makes it possible to compare and evaluate health care quality between different institutions in countries. This study aimed to assess the performance of the European System for Cardiac Operative Risk Evaluation (EuroSCORE) model in estimating the risk of mortality of cardiac surgery patients of our hospital.

PATIENTS AND METHODS

The additive and logistic EuroSCORE models were applied to all patients who underwent cardiac surgery with extracorporeal circulation from the time the cardiac surgery unit was opened in our center in November 2002 until February 2006. All data were obtained prospectively when the patients were admitted to the Intensive Care Unit. Mortality observed was compared with that estimated in the following subgroups: global cardiac surgery, isolated coronary surgery, isolated valvular surgery, combined valvular and coronary surgery and thoracic aorta surgery. Model discrimination was tested by determining the area under the receiver operating characteristic (ROC) curve.

RESULTS

We studied 1,053 patients who had several differences with the EuroScore model population. Overall observed mortality was 2.2% (95% CI 1.2 - 3.1). The EuroSCORE models overestimated mortality (additive predicted 5%, logistic predicted 4.6%). Mortality of coronary bypass graft surgery was 1.2% and both EuroSCORE models overestimated it. Discriminative power of both models was good with an Area under ROC curve for both models of 0.78 and 0.79.

CONCLUSIONS

The use of both EuroSCORE models overestimated overall observed mortality and that of the different surgical subgroups of cardiac surgery performed in our institution.