Can EuroSCORE predict direct costs of cardiac surgery?

Carotid artery stenting prior to coronary artery bypass grafting in patients with carotid stenosis: Clinical outcomes

OBJECTIVES

Management of patients undergoing coronary artery bypass grafting (CABG) with obstructive disease of the carotid arteries is still a matter of debate. We compared the results of staged carotid artery stenting (CAS) before CABG in patients with carotid lesions.

MATERIALS AND METHOD

Patients with significant carotid artery disease who were deemed to simultaneously suffer from an obstructive coronary artery disease requiring CABG from 2008 to 2018 were screened and enrolled in this study. We performed a staged CAS in cases with ≥60% stenosis and neurological symptoms or asymptomatic patients with ≥80% carotid artery stenosis. Patients with bilateral carotid lesions received sequential CAS within three weeks. Six weeks after the CAS procedure, all patients underwent CABG.

RESULTS

A total of 142 patients were included. Eighty-five of these had neurological symptoms, while the remaining 40% were asymptomatic. Thirty-one patients underwent sequential CAS for bilateral lesions. The cerebrovascular event (CVE) following CAS (3 patients) and CABG (3 patients) was 4.2%. There was only a single case of mortality in this cohort. Although it was not statistically significant, CVE after CABG was more frequent in patients with bilateral carotid disease.

CONCLUSIONS

Our results showed that staged CAS could be performed with minimal adverse outcomes in patients suffering from a simultaneous occlusive disease of carotids and coronary arteries before CABG. Bilateral CAS will further decrease cerebrovascular events and could be performed consequently or concomitantly.

EuroScore and IL-6 predict the course in ICU after cardiac surgery

BACKGROUND

Despite modern advances in intensive care medicine and surgical techniques, mortality rates in cardiac surgical patients are still about 3%. Considerable efforts were made to predict morbidity and mortality after cardiac surgery. In this study, we analysed the predictive properties of EuroScore and IL-6 for mortality in ICU, prolonged postoperative mechanical ventilation, and prolonged stay in ICU.

METHODS

We enrolled 2972 patients undergoing cardiac surgery. The patients either underwent aortic valve surgery (AV), mitral valve surgery (MV), coronary artery bypass grafting (CABG), and combined operations of aortic valve and coronary artery bypass grafting (AV + CABG) or of mitral and tricuspid valve (MV + TV). Different laboratory and clinical parameters were analysed.

RESULTS

EuroScore as well as IL-6 were associated with increased mortality after cardiac surgery. Furthermore, a higher EuroScore and elevated levels of IL-6 were predictors for prolonged mechanical ventilation and a longer stay in ICU. Especially, highly significant elevated IL-6 levels and an increased EuroScore showed a strong association. Statistics suggested superiority when both parameters were combined in a single model.

CONCLUSION

Our results suggest that EuroScore and IL-6 are helpful in predicting the course in ICU after cardiac surgery, and therefore, the use of intensive care resources. Especially, the combination of highly elevated levels of IL-6 and EuroScore may prove to be excellent predictors for an unfortunate postoperative course in ICU.

Prediction of Postoperative Outcomes and Long-Term Survival in Cardiac Surgical Patients Using the Intensive Care National Audit & Research Centre Score

OBJECTIVES

Scoring systems used in cardiac surgery, such as the European System for Cardiac Operative Risk Evaluation and the Society of Thoracic Surgeons scoring systems, do not adjust for events that take place intraoperatively. The authors hypothesized that intensive care unit scoring systems such as the Intensive Care National Audit & Research Centre (ICNARC) could predict accurately not only in-hospital mortality, but also other significant complications, as well as long-term survival after cardiac surgery.

DESIGN

Prospective cohort study using perioperative data from the ICNARC Audit and Dendrite database.

SETTING

Single tertiary referral cardiac surgery center.

PARTICIPANTS

A total of 4,446 consecutive cardiac surgical patients who had surgery between January 2011 and April 2018.

INTERVENTIONS

Comparison of scoring systems to predict postoperative outcomes.

MEASUREMENTS AND RESULTS

Receiver operating curves (ROCs) were used to evaluate how well the ICNARC scores predicted in-hospital mortality and postoperative complications (renal failure, pulmonary complications, gastrointestinal complications, and multiorgan failure). Cox regression analysis was used to determine factors affecting long-term survival. The C-indices for the ROC graphs for the ICNARC score were 0.840 for in-hospital mortality, 0.858 for renal failure, 0.665 for pulmonary complications, 0.764 for gastrointestinal complications, 0.702 for neurological complications in general and 0.654 for confusion, and 0.885 for multiorgan failure. From Cox regression analysis, the significant (p < 0.05) predictors of midterm mortality (5 years) were a higher ICNARC score, a higher age at surgery, chronic obstructive pulmonary disease, preoperative renal failure, preoperative neurological comorbidity, arteriopathy, and non-coronary artery bypass graft surgery.

CONCLUSION

The ICNARC scoring system is simple and can be used as an early warning screening tool to predict which patients are at higher risk for postoperative organ failure.

Intermediate Care Unit After Cardiac Surgery: Impact on Length of Stay and Outcomes

INTRODUCTION AND OBJECTIVES

Current postoperative management of adult cardiac surgery often comprises transfer from the intensive care unit (ICU) to a conventional ward. Intermediate care units (IMCU) permit hospital resource optimization. We analyzed the impact of an IMCU on length of stay (both ICU and in-hospital) and outcomes (in-hospital mortality and 30-day readmissions) after adult cardiac surgery (IMCU-CS).

METHODS

From November 2012 to April 2015, 1324 consecutive patients were admitted to a university hospital for cardiac surgery. In May 2014, an IMCU-CS was established for postoperative care. For the purposes of this study, patients were classified into 2 groups, depending on the admission period: pre-IMCU-CS (November 2012-April 2014, n=674) and post-IMCU-CS (May 2014-April 2015, n=650).

RESULTS

There were no statistically significant differences in age, sex, risk factors, comorbidities, EuroSCORE 2, left ventricular ejection fraction, or the types of surgery (valvular in 53%, coronary in 26%, valvular plus coronary in 11.5%, and aorta in 1.8%). The ICU length of stay decreased from 4.9±11 to 2.9±6 days (mean±standard deviation; P<.001); 2 [1-4] to 1 [0-3] (median [Q1-Q3]); in-hospital length of stay decreased from 13.5±15 to 12.7±11 days (mean±standard deviation; P=.01); 9 [7-13] to 9 [7-11] (median [Q1-Q3]), in pre-IMCU-CS to post-IMCU-CS, respectively. There were no statistically significant differences in in-hospital mortality (4.9% vs 3.5%; P=.28) or 30-day readmission rate (4.3% vs 4.2%; P=.89).

CONCLUSIONS

After the establishment of an IMCU-CS for postoperative cardiac surgery, there was a reduction in ICU and in-hospital mean lengths of stay with no increase in in-hospital mortality or 30-day readmissions.

Predicting operative mortality in octogenarians for isolated coronary artery bypass grafting surgery: a retrospective study

Background

Available cardiac surgery risk scores have not been validated in octogenarians. Our objective was to compare the predictive ability of the Society of Thoracic Surgeons (STS) score, EuroSCORE I, and EuroSCORE II in elderly patients undergoing isolated coronary artery bypass grafting surgery (CABG).

Methods

All patients who underwent isolated CABG (2002 – 2008) were identified from the Alberta Provincial Project for Outcomes Assessment in Coronary Heart Disease (APPROACH) registry. All patients aged 80 and older (n = 304) were then matched 1:2 with a randomly selected control group of patients under age 80 (n = 608 of 4732). Risk scores were calculated. Discriminatory accuracy of the risk models was assessed by plotting the areas under the receiver operator characteristic (AUC) and comparing the observed to predicted operative mortality.

Results

Octogenarians had a significantly higher predicted mortality by STS Score (3 ± 2% vs. 1 ± 1%; p < 0.001), additive EuroSCORE (8 ± 3% vs. 4 ± 3%; p < 0.001), logistic EuroSCORE (15 ± 14% vs. 5 ± 6%; p < 0.001), and EuroSCORE II (4 ± 3% vs. 2 ± 2%; p < 0.001) compared to patients under age 80 years. Observed mortality was 2% and 1% for patients age 80 and older and under age 80, respectively (p = 0.323). AUC revealed areas for STS, additive and logistic EuroSCORE I and EuroSCORE II, respectively, for patients age 80 and older (0.671, 0.709, 0.694, 0.794) and under age 80 (0.829, 0.750, 0.785, 0.845).

Conclusion

All risk prediction models assessed overestimated surgical risk, particularly in octogenarians. EuroSCORE II demonstrated better discriminatory accuracy in this population. Inclusion of new variables into these risk models, such as frailty, may allow for more accurate prediction of true operative risk.

High preoperative monocyte count/high-density lipoprotein ratio is associated with postoperative atrial fibrillation and mortality in coronary artery bypass grafting

Objectives

The monocyte to high-density lipoprotein ratio has recently emerged as an indicator of inflammation and oxidative stress. The aim of this study was to evaluate the association of the monocyte to high-density lipoprotein ratio with postoperative atrial fibrillation and mortality in coronary artery bypass grafting.

Methods

Six hundred and sixty-two patients who were in sinus rhythm preoperatively and who had isolated coronary artery bypass grafting were retrospectively included in the study. Patients who had atrial fibrillation in the early postoperative period were enrolled in group 1 ( n  = 153); patients who remained in sinus rhythm in the early postoperative period were included in group 2 ( n  = 509). The clinical and demographic data of the patients, biochemical and complete blood count parameters, preoperative monocyte count/high-density lipoprotein cholesterol ratio, and operative and postoperative data were recorded.

Results

Preoperative monocyte counts ( P  = 0.0001), monocyte count/high-density lipoprotein cholesterol ratio ( P = 0.0001) and C-reactive protein levels ( P  = 0.0001) were significantly increased in group 1. In the first month, 8 patients in group 1 (5.2%) and 5 patients in group 2 (1.0%) died, which was statistically significant ( P  = 0.003). In univariate and multivariate logistic regression analyses, an elevated preoperative monocyte count/high-density lipoprotein cholesterol ratio ( P  = 0.03) and C-reactive protein levels ( P  = 0.0001) were predictors of postoperative atrial fibrillation. Preoperative monocyte counts ( P  = 0.001), monocyte count/high-density lipoprotein cholesterol ratio ( P  = 0.0001) and the use of inotropic support ( P  = 0.0001) were also predictors of mortality in the early postoperative period.

Conclusions

We have observed that high preoperative monocyte count/ high-density lipoprotein ratio was associated with postoperative atrial fibrillation and mortality after coronary artery bypass grafting operation.

Assessment of the EuroSCORE risk scoring system for patients undergoing coronary artery bypass graft surgery in a group of Iranian patients

Background and Aims:

Previous studies around the world indicated validity and accuracy of European System for Cardiac Operative Risk Evaluation (EuroSCORE) risk scoring system we evaluated the EuroSCORE risk scoring system for patients undergoing coronary artery bypass graft (CABG) surgery in a group of Iranian patients.

Materials and Methods:

In this cohort 2220 patients more than 18 years, who were performed CABG surgery in Massih Daneshvari Hospital, from January 2004 to March 2010 were recruited. Predicted mortality risk scores were calculated using logistic EuroSCORE and Acute Physiology and Chronic Health Evaluation II (APACHE II) and compared with observed mortality. Calibration was measured by the Hosmer–Lemeshow (HL) test and discrimination by using the receiver operating characteristic (ROC) curve area.

Results:

Of the 2220 patients, in hospital deaths occurred in 270 patients (mortality rate of 12.2%). The accuracy of mortality prediction in the logistic EuroSCORE and APACHE II model was 89.1%; in the local EuroSCORE (logistic) was 91.89%; and in the local EuroSCORE support vector machines (SVM) was 98.6%. The area under curve for ROC curve, was 0.724 (95% confidence interval [CI]: 0.57–0.88) for logistic EuroSCORE; 0.836 (95% CI: 0.731–0.942) for local EuroSCORE (logistic); 0.978 (95% CI: 0.937–1) for Local EuroSCORE (SVM); and 0.832 (95% CI: 0.723–0.941) for APACHE II model. The HL test showed good calibration for the local EuroSCORE (SVM), APACHE II model and local EuroSCORE (logistic) (P = 0.823, P = 0.748 and P = 0.06 respectively); but there was a significant difference between expected and observed mortality according to EuroSCORE model (P = 0.033).

Conclusion:

We detected logistic EuroSCORE risk model is not applicable on Iranian patients undergoing CABG surgery.

EuroSCORE models in a cohort of patients with valvular heart disease and a high prevalence of rheumatic fever submitted to surgical procedures

Objectives

Epidemiological differences can be found between Brazilian and European valvular heart disease patients. The prevalence of heart valve diseases due to rheumatic disease is significantly higher in the Brazilian compared with the European population. Therefore, they could have different risks during and after cardiac surgery. The aim of this study was to evaluate the applicability of the additive and logistic EuroSCORE and EuroSCORE II in a cohort of high-risk patients with valvular heart disease of predominantly rheumatic aetiology submitted to surgery.

Methods

Between 1 February and 30 December 2009, 540 consecutive patients scheduled for valvular heart surgery were included in this study. In this set of patients, we examined the performance of the additive, logistic, and EuroSCORE II models for predicting in-hospital mortality. Calibration of each model was assessed by comparing predicted and observed in-hospital mortality and by the goodness of fit of the Hosmer-Lemeshow chi-square test. Discrimination performance of the model was evaluated with the receiver operating characteristic (ROC) curve analysis.

Results

The mean age was 56 ± 16 years, 50.6% were female, and the mortality rate was 16.0% (6.0% in elective surgery and 34.0% in emergency/urgency surgery). Mortality rates were estimated according to the additive and logistic EuroSCORE and EuroSCORE II at 6.1%, 8.7%, and 4.3%, respectively. The AUC was 0.76 (95% confidence interval [95% CI] 0.70–0.81) for the additive EuroSCORE, 0.76 (95% CI 0.70–0.81) for the logistic EuroSCORE and 0.81 (95% CI 0.76–0.86) for EuroSCORE II. Hosmer-Lemeshow goodness-of-fit statistics were P = 0.52, P = 0.07, and P = 0.12 for additive, logistic EuroSCORE, and EuroSCORE II.

Conclusions

In this cohort of Brazilian patients with valvular heart disease submitted to surgical procedure, the EuroSCORE models had a good discriminatory capacity; however, the calibration was compromised because of an underestimation of the mortality rate.

Evaluation of Quality Of Life after Cardiac Surgery in High-Risk Patients

<p><b>Background:</b> Conventionally, there is controversy over subjecting high-risk patients to cardiac operations, due to major postoperative complications. Higher survival rates and less morbidity as well as better quality of life can be good predictors of the outcome of surgery. This study evaluates the quality of life before and 12 months after cardiac operations on high-risk patients.</p><p><b>Methods:</b> In this study, the European System for Cardiac Operative Risk Evaluation (EuroSCORE) II was used to separate high-risk patients from others. The quality of life was assessed using the Medical Outcomes Study 36-item Short Form Health Survey (SF-36) before surgery and one year afterward. Based on SF-36, the score for each of the eight different dimensions of the quality of life was quantified; and, their differences between pre-surgery and post-follow up period were analyzed.</p><p><b>Results:</b> 126 high-risk patients were included in this study. The mean age of the patients was 64.29 � 12.35 years. The median of EuroSCORE II score in these cases was 6.83 (6.04-25.98). The results reveal that the majority of the quality of life dimensions, except mental health, improved significantly after the follow-up period.</p><p><b>Conclusion:</b> Cardiac surgery on high-risk patients can noticeably promote the different aspects of their quality of life; although, such improvements should be considered against surgical complications.</p>

In-hospital mortality risk assessment in elective and non-elective cardiac surgery: a comparison between EuroSCORE II and age, creatinine, ejection fraction score

OBJECTIVES

Age, creatinine, ejection fraction (ACEF) score is a simplified algorithm for prediction of mortality after elective cardiac surgery. Although mainly conceived for elective cardiac surgery, no information is available on its performance in non-elective surgery and on comparison with the new EuroSCORE II. This study was undertaken to compare the performance of ACEF score and EuroSCORE II within classes of urgency.

METHODS

Complete data on 13 871 consecutive patients who underwent major cardiac surgery in a 6-year period were retrieved from three prospective institutional databases. Discriminatory power was assessed using the c-index and h with Delong, bootstrap and Venkatraman methods. Calibration was evaluated with calibration curves and associated statistics.

RESULTS

The in-hospital mortality rate was 2.5%. The discriminatory power of ACEF score within elective and non-elective surgery was similar (area under the curve (AUC) 0.71, 95% confidence interval (CI) 0.67-0.74 and AUC 0.68, 95% CI 0.62-0.73, respectively) but significantly lower than that of EuroSCORE II (AUC 0.80, 95% CI 0.77-0.83 for elective surgery; AUC 0.82, 95% CI 0.78-0.85 for non-elective surgery). The calibration patterns were different in the two subgroups, but the summary statistics underscored a miscalibration in both of them (U-statistic and Spiegelhalter Z-test P-values <0.05). Even the calibration of EuroSCORE II was insufficient, although it was demonstrated to be well calibrated in the first tertile of predicted risk.

CONCLUSIONS

This study demonstrated that the performance of ACEF score in predicting in-hospital mortality in elective and non-elective cardiac surgery is comparable. Nonetheless, it is not as satisfactory as the new EuroSCORE II, as its discrimination is significantly lower and it is also miscalibrated.

Preoperative risk stratification models fail to predict hospital cost of cardiac surgery patients

Background

Preoperative risk stratification models have previously been suggested to predict cardiac surgery unit costs. However, there is a lack of consistency in their reliability in this field. In this study we aim to test the correlation between the values of six commonly known preoperative scoring systems and evaluate their reliability at predicting unit costs of cardiac surgery patients.

Methods

Over a period of 14 months all consecutive adult patients undergoing cardiac surgery on cardiopulmonary bypass were prospectively classified using six preoperative scoring models (EuroSCORE, Parsonnet, Ontario, French, Pons and CABDEAL). Transplantation patients were the only patients we excluded. Total hospital costs for each patient were calculated independently on a daily basis using the bottom up method. The full unit costs were calculated including preoperative diagnostic tests, operating room cost, disposable materials, drugs, blood components as well as costs for personnel and fixed hospital costs. The correlation between hospital cost and the six models was determined by linear regression analysis. Both Spearman’s and Pearson’s correlation coefficients were calculated from the regression lines. An analysis of residuals was performed to determine the quality of the regression.

Results

A total of 887 patients were operated on for CABG (n = 608), valve (n = 142), CABG plus valve (n = 100), thoracic aorta (n = 33) and ventricular assist devices (n = 4). Mean age of the patients was 68.3±9.9 years, 27.6% were female. 30-day mortality rate was 4.1%. Correlation between the six models and hospital cost was weak (Pearson’s: r < 0.30; Spearman’s: r < 0.40).

Conclusion

The risk stratification models in this study are not reliable at predicting total costs of cardiac surgical patients. We therefore do not recommend their use for this purpose.

Early results after synchronous carotid stent placement and coronary artery bypass graft in patients with asymptomatic carotid stenosis

BACKGROUND

The optimal management of patients with combined carotid and coronary artery disease requiring cardiac surgery is still unknown. Staged carotid endarterectomy and carotid artery stenting (CAS), each followed by coronary artery bypass graft (CABG), are options frequently employed. However, for patients with severe carotid artery disease in urgent need of open cardiac revascularization, staged operations may not be the most appropriate alternative. The aim of this study was to describe our experience using a synchronous CAS-CABG method with minimal interprocedural time. We used this synchronous combination of procedures in patients with combined carotid and coronary artery disease admitted for urgent CABG.

METHODS

Patients with concomitant severe carotid and coronary artery disease scheduled for synchronous CAS and urgent CABG between December 2006 and January 2010 were included in the study. All procedures were performed at a single center: the Cardiovascular Foundation of Colombia, in Floridablanca, Santander, Colombia. The study cohort was characterized according to demographic and clinical characteristics, which included degree of carotid stenosis, presence/absence of preoperative neurological symptoms, and cardiac operative risk profile. All patients underwent CAS under embolic protection devices and then CABG within the next 2 hours. Patients received aspirin pre- and postprocedure but were started on clopidogrel only after CABG. The primary end point of the study was the composite incidence rate of myocardial infarction, stroke, and death 30 days after CAS-CABG.

RESULTS

Fifteen patients with concomitant severe carotid and coronary artery disease underwent synchronous CAS-CABG. Most patients (60%) were men, and mean (± standard deviation) age was 65.2 (± 8.4) years. Most patients (93%) were neurologically asymptomatic. The median (interquartile range) ejection fraction and logistic European System for Cardiac Operative Risk Evaluation (EuroSCORE) for the cohort were 55% (36%-62%) and 9.7% (4.6%-14.8%), respectively. There were no deaths, major strokes, minor strokes, or myocardial infarctions during the procedure or within 30 days of CAS-CABG. One patient experienced neurological symptoms likely as a result of transient ischemic attack ipsilateral to the CAS procedure. None of the patients required cardiac or carotid reinterventions, and there were no cases of postoperative bleeding requiring reoperation.

CONCLUSIONS

Synchronous CAS-CABG, when CABG is performed within the 2 hours of the CAS procedure, may be a viable alternative to the more generally accepted staged combination, particularly among patients for whom CABG cannot be postponed. We hope that this strategy will be further evaluated in larger prospective studies and adequately powered randomized clinical trials.

The cost of open heart surgery in Nigeria

Introduction

Open Heart Surgery (OHS) is not commonly practiced in Nigeria and most patients who require OHS are referred abroad. There has recently been a resurgence of interest in establishing OHS services in Nigeria but the cost is unknown. The aim of this study was to determine the direct cost of OHS procedures in Nigeria.

Methods

The study was performed prospectively from November to December 2011. Three concurrent operations were selected as being representative of the scope of surgery offered at our institution. These procedures were Atrial Septal Defect (ASD) Repair, Off Pump Coronary Artery Bypass Grafting (OPCAB) and Mitral Valve Replacement (MVR). Cost categories contributing to direct costs of OHS (Investigations, Drugs, Perfusion, Theatre, Intensive Care, Honorarium and Hospital Stay) were tracked to determine the total direct cost for the 3 selected OHS procedures.

Results

ASD repair cost $ 6,230 (Drugs $600, Intensive Care $410, Investigations $955, Perfusion $1080, Theatre $1360, Honorarium $925, Hospital Stay $900). OPCAB cost $8,430 (Drugs $740, Intensive Care $625, Investigations $3,020, Perfusion $915, Theatre $1305, Honorarium $925, Hospital Stay $900). MVR with a bioprosthetic valve cost $11,200 (Drugs $1200, Intensive Care $500, Investigations $3040, Perfusion $1100, Theatre $3,535, Honorarium $925, Hospital Stay $900).

Conclusion

The direct cost of OHS in Nigeria currently ranges between $6,230 and $11,200. These costs compare favorably with the cost of OHS abroad and can serve as a financial incentive to patients, sponsors and stakeholders to have OHS procedures done in Nigeria.

Computerized prediction of intensive care unit discharge after cardiac surgery: development and validation of a Gaussian processes model

Background

The intensive care unit (ICU) length of stay (LOS) of patients undergoing cardiac surgery may vary considerably, and is often difficult to predict within the first hours after admission. The early clinical evolution of a cardiac surgery patient might be predictive for his LOS. The purpose of the present study was to develop a predictive model for ICU discharge after non-emergency cardiac surgery, by analyzing the first 4 hours of data in the computerized medical record of these patients with Gaussian processes (GP), a machine learning technique.

Methods

Non-interventional study. Predictive modeling, separate development (n = 461) and validation (n = 499) cohort. GP models were developed to predict the probability of ICU discharge the day after surgery (classification task), and to predict the day of ICU discharge as a discrete variable (regression task). GP predictions were compared with predictions by EuroSCORE, nurses and physicians. The classification task was evaluated using aROC for discrimination, and Brier Score, Brier Score Scaled, and Hosmer-Lemeshow test for calibration. The regression task was evaluated by comparing median actual and predicted discharge, loss penalty function (LPF) ((actual-predicted)/actual) and calculating root mean squared relative errors (RMSRE).

Results

Median (P25-P75) ICU length of stay was 3 (2-5) days. For classification, the GP model showed an aROC of 0.758 which was significantly higher than the predictions by nurses, but not better than EuroSCORE and physicians. The GP had the best calibration, with a Brier Score of 0.179 and Hosmer-Lemeshow p-value of 0.382. For regression, GP had the highest proportion of patients with a correctly predicted day of discharge (40%), which was significantly better than the EuroSCORE (p < 0.001) and nurses (p = 0.044) but equivalent to physicians. GP had the lowest RMSRE (0.408) of all predictive models.

Conclusions

A GP model that uses PDMS data of the first 4 hours after admission in the ICU of scheduled adult cardiac surgery patients was able to predict discharge from the ICU as a classification as well as a regression task. The GP model demonstrated a significantly better discriminative power than the EuroSCORE and the ICU nurses, and at least as good as predictions done by ICU physicians. The GP model was the only well calibrated model.

Predicting prolonged intensive care unit stays in older cardiac surgery patients: a validation study

PURPOSE

In cardiac surgery prediction models identifying patients at risk of prolonged stay at the Intensive Care Unit (ICU) are used to optimize treatment and use of ICU resources. A recent systematic validation study of 14 of these models identified three models with a good predictive performance across patients of all ages. It is however unclear how these models perform in older patients, who nowadays form a considerable part of this patient population. The current study specifically validates the performance of these three models in older cardiac surgery patients and quantifies how their performance changes with increasing age of patients.

METHODS

The Parsonnet model, the EuroSCORE, and a model by Huijskes and colleagues were validated using prospectively collected data of 11,395 cardiac surgery patients. Performance of the models was described by discrimination (area under the ROC curve, AUC) and calibration.

RESULTS

For the Parsonnet model, the EuroSCORE and the Huijskes model discrimination clearly decreased with increasing age (AUCs of 0.76, 0.71 and 0.72 for ages 70-75 and 0.72, 0.70 and 0.72, respectively, for ages 75-80 and 0.68, 0.64 and 0.69, respectively, above 80 years). The models showed poor calibration in patients aged >70 (p values for fit of the models <0.006).

CONCLUSIONS

To optimize treatment and ICU resources, risk prediction for prolonged ICU stay after cardiac surgery using the existing models should be done with great care for older patients.

Prediction models for prolonged intensive care unit stay after cardiac surgery: systematic review and validation study

BACKGROUND

Several models have been developed to predict prolonged stay in the intensive care unit (ICU) after cardiac surgery. However, no extensive quantitative validation of these models has yet been conducted. This study sought to identify and validate existing prediction models for prolonged ICU length of stay after cardiac surgery.

METHODS AND RESULTS

After a systematic review of the literature, the identified models were applied on a large registry database comprising 11 395 cardiac surgical interventions. The probabilities of prolonged ICU length of stay based on the models were compared with the actual outcome to assess the discrimination and calibration performance of the models. Literature review identified 20 models, of which 14 could be included. Of the 6 models for the general cardiac surgery population, the Parsonnet model showed the best discrimination (area under the receiver operating characteristic curve=0.75 [95% confidence interval, 0.73 to 0.76]), followed by the European system for cardiac operative risk evaluation (EuroSCORE) (0.71 [0.70 to 0.72]) and a model by Huijskes and colleagues (0.71 [0.70 to 0.73]). Most of the models showed good calibration.

CONCLUSIONS

In this validation of prediction models for prolonged ICU length of stay, 2 widely implemented models (Parsonnet, EuroSCORE), although originally designed for prediction of mortality, were superior in identifying patients with prolonged ICU length of stay.

Are coronary angiograms of value in the risk stratification of patients undergoing coronary artery bypass surgery?

INTRODUCTION

There are currently more than 20 risk-scoring systems that attempt to predict peri-operative mortality following coronary artery bypass surgery (CABG). All these scoring systems use objective criteria to assess operative risk. Angiographic data are currently not included in any of these systems. This pilot study assessed the value of coronary angiography in predicting peri-operative mortality following CABG.

PATIENTS AND METHODS

Fourteen patients who died following first-time isolated CABG surgery were identified. These were matched with 14 patients of similar age, sex, left ventricle function and European System for Cardiac Operative Risk Evaluation (EuroSCORE). A panel of 25 clinicians were given details of the patients' age, sex, diabetic status, family history, smoking history, hypertensive status, lipid status, pre-operative symptoms, left ventricle ejection fraction and weight and shown the coronary angiograms of the patient. They were asked to predict the outcome following CABG for each patient.

RESULTS

Receiver operator characteristic curves were constructed and the area under the curves calculated and analysed using a commercially available statistical package (PRISM). The area under the curve for the group was 0.6820 for the group. Consultant clinicians achieved an area of 0.6789 versus their trainees 0.6844 (P = NS). The cardiologists achieved an area of 0.7063 versus the cardiothoracic surgeons 0.6491 (P = NS).

CONCLUSIONS

Despite the EuroSCORE predicting equal risk for the two groups of patients, it would appear that clinicians are able to identify individual higher risk patients by assessing pre-operatively the quality of the patient's coronary vasculature. Although the clinicians were able to predict individual patient mortality better than the EuroSCORE, the area under the curve indicates that it is not a robust method and clinicians, with all the clinical information to hand, are only moderately good at predicting the outcome following coronary artery bypass surgery.

Thoracic aortic aneurysm repair. Direct hospital cost and Diagnosis Related Group reimbursement

OBJECTIVE

The main objective of this study was to analyze direct hospital cost and to compare cost with existing DRG reimbursement for open repair of thoracic and thoraco-abdominal aortic disease. STUDY SAMPLE AND METHODOLOGY: Between January 2003 and September 2003, the cost of treatment for 24 surgical procedures on ascending aorta and arch, descending or thoraco-abdominal aortic disease were examined prospectively. Seven patients had urgent or emergency surgeries. Ten had sternotomies for disease of the ascending aorta and aortic arch; two had left thoracotomies and three thoraco-laparotomy incisions with procedures performed on x-corporeal circulation. Nine other patients had more distal thoraco-abdominal aortic operations with a clamp-and-sew technique. Micro-cost analysis was performed on each hospital stay, in addition overhead hospital costs were allocated to each procedure.

RESULTS

The patients were grouped by discharge diagnosis (ICD-10) and surgical procedure performed (NCSP) into Norwegian DRG code. Patient with surgery on ascending aorta & aortic arch were allocated to DRG 108 (n=9) or 483 (tracheostomy, n=1) while patient with surgery on descending or thoraco-abdominal aorta were allocated to DRG 108 (n=3), 110 (n=4), 111 (n=4) or 483 (tracheostomy, n=3). The mean EuroSCORE for patients with proximal aortic disease was 11 (5-18), and the length of stay was 5 days (range 3-8 days), spending 2 days (range 1-7 days) in thoracic intensive care unit. For patients with distal aortic disease the mean Euroscore was 7 (2-14), and the mean length of stay 10 days (range 4-23 days) with a mean 4 days (range 1-13 days) in intensive care unit. Eight patients developed medical problems requiring new surgical procedures or prolonged ICU stay. The average direct hospital cost for proximal aortic surgery was USD 15,877 (USD 1=NOK 7.5) while the respective 100% DRG reimbursement including one patient needing a tracheostomy, was 19 803 USD. For patients with distal aortic disease, average direct hospital cost was 23 005 USD and DRG reimbursement including patients needing a tracheostomy was 31543 USD.

CONCLUSION

Our results underscore previous findings that these patients are resource intensive. This study shows that Norwegian 100% DRG reimbursement did over-compensate observed total hospital costs in this cohort. Detailed analysis showed that this was due to the higher DRG reimbursement for patients needing prolonged ventilatory support. Thus the actual DRG reimbursement seems to be relevant to the tertiary hospital actual costs when these complicated patients are considered as a group. It remains however unclear whether this reimbursement is sufficient to support the scientific infrastructure for new knowledge and skills needed for the further refinement of treatment.

Risk adjusted resource utilization for AMI patients treated in Japanese hospitals

Though risk adjustment is necessary in order to make equitable comparisons of resource utilization in the treatment of acute myocardial infarction patients, there is little in the literature that can be practically applied without access to clinical records or specialized registries. The aim of this study is to show that effective models of resource utilization can be developed based on administrative data, and to demonstrate a practical application of the same models by comparing the risk-adjusted performance of the hospitals in our dataset. The study sample included 1748 AMI cases discharged from 10 large, private teaching hospitals in Japan, between 10 April 2001 and 30 June 2004. Explanatory variables included procedures (CABG and PCI), length of stay, outcome, patient demographics, diagnosis and comorbidity status. Multiple linear regression models constructed for the study were able to account for 66.5, 27.7, and 58.4% of observed variation in total charges, length of stay and charges per day, respectively. The performance of models constructed for this study was comparable to or better than performance reported by other studies that made use of explanatory variables extracted from clinical data. The use of administrative data in risk adjustment makes broad scale application of risk adjustment feasible.

The Toronto Risk Score for adverse events following cardiac surgery

OBJECTIVE

To develop and validate an objective and reliable measure of acuity that will identify high-risk patients and predict length of stay following all cardiac surgery procedures.

METHODS

Logistical regression analysis of 12,683 patients undergoing cardiac surgery between 1996 and 2000 was used to identify the independent predictors of postoperative adverse events (AEs, defined as death, myocardial infarction, low cardiac output syndrome, postoperative renal failure, stroke or deep sternal wound infection). The rounded ORs for each of the 18 predictors of AEs were summed to calculate the Toronto Risk Score (TRS) for each patient. Weighted linear regression was used to determine the relationship between TRS and length of stay in the 4378 patients who underwent cardiac surgery between 2001 and 2002.

RESULTS

TRS was significantly associated with cardiovascular intensive care unit length of stay (R2=0.85, slope=0.42, intercept=0.4; P<0.001). For each unit increase in TRS, cardiovascular intensive care unit length of stay increased by 0.4+/-0.05 days. TRS was also significantly associated with total postoperative length of stay (R2=0.88, slope=0.71, intercept=4.9; P<0.001). TRS captured a significant increase in acuity from 1996 and 2000 (5.12+/-3.5) to 2001 and 2002 (5.54+/-3.5; P<0.001). Despite increased acuity, AEs were reduced in 2001 and 2002 (8.1%) compared with 1996 to 2000 (9.8%; P=0.012).

CONCLUSIONS

The TRS is a valid measure of acuity that can identify patients who are at high risk of experiencing an AE and having prolonged length of stay after any cardiac surgery procedure, capture changes in acuity over time and allow for continuous quality performance evaluation.

Risk stratification models fail to predict hospital costs of cardiac surgery patients

BACKGROUND

The aim of this prospective study was to determine if commonly used risk stratification models can predict total hospital costs in cardiac surgical patients.

METHODS

Between October 1st and December 31st 2003, all consecutive adult patients undergoing cardiac surgery on CPB at our institution were classified using seven risk stratification scoring systems: EuroSCORE, Cleveland, Parsonnet, Ontario, French, Pons, and CABDEAL. Total hospital costs for each patient were calculated on a daily basis including preoperative diagnostic tests, operating room costs, disposable materials, drugs, blood components, costs for personnel, and hospital fixed-costs. Linear regression analysis was used to determine the correlation between costs and the seven risk stratifications models as well as length of stay (LOS) on ICU. The Spearman correlation coefficient was calculated from the regression line, and an analysis of residuals was performed to determine the quality of the regression.

RESULTS

A total of 252 patients were operated for CABG (n=175), valve (n=39), CABG plus valve (n=21), thoracic aorta (n=13) and miscellaneous (2 myxoma, 1 ASD, 1 pulmonary embolism). Mean age of the patients was 66.0+/-11.4 years, 29.4% were female. LOS on ICU was 3.3+/-6.3 days and the 30-day mortality rate was 6.7%. Spearman correlation between the seven risk stratification models and hospital costs was below r=0.32 (p=0.0001), but was r=0.94 (p=0.0001) between ICU LOS and costs.

CONCLUSIONS

Total hospital costs can be identified by length of ICU stay. None of the common risk stratification models accurately predicted total hospital costs in cardiac surgical patients.

EuroSCORE Predicts Long-Term Mortality After Heart Valve Surgery

BACKGROUND

The European System for Cardiac Operative Risk Evaluation (EuroSCORE) is the most rigorously evaluated scoring system in cardiac surgery. We sought to evaluate the performance of EuroSCORE in the prediction of long-term mortality in patients undergoing heart valve surgery.

METHODS

Medical records of patients with isolated or combined heart valve surgery, who were discharged alive (n = 1035), were retrospectively reviewed. Their operative surgical risks were calculated according to EuroSCORE model (standard and logistic). Long-term survival data (mean follow-up 4.5 +/- 3.1 years) were obtained from the National Death Index. Kaplan-Meier curves of the quartiles of standard and logistic EuroSCORE were plotted.

RESULTS

The estimated 5-year survival rates of the quartiles in the standard and logistic EuroSCORE model were: 90.0% +/- 2.3%, 85.1% +/- 2.3%, 64.8% +/- 3.3%, and 55.1% +/- 3.7% (p < 0.0001, log-rank test with adjustment for trend) and 90.4% +/- 2.2%, 86.4% +/- 2.5%, 66.9% +/- 3.3%, and 56.1% +/- 3.3% (p < 0.0001, log-rank test with adjustment for trend) respectively. The odds of death in the highest-risk quartile were 7.46- and 7.82-fold higher than the odds of death in the lowest-risk quartile for standard and logistic EuroSCORE respectively.

CONCLUSIONS

EuroSCORE can be used to predict not only in-hospital mortality, for which it was originally designed, but also long-term mortality in the whole context of heart valve surgery. This outcome can be predicted using the standard EuroSCORE, which is very simple and easy in its calculation.

EuroSCORE Predicts Intensive Care Unit Stay and Costs of Open Heart Surgery

BACKGROUND

This study aimed to determine whether the preoperative risk stratification model EuroSCORE predicts the different components of resource utilization in open heart surgery.

METHODS

Data for all adult patients undergoing heart surgery at the University Hospital of Lund, Sweden, between 1999 and 2002 were prospectively collected. Costs were calculated for the surgery and intensive care and ward stay for each patient (excluding transplant cases and patients who died intraoperatively). Regression analysis was applied to evaluate the correlation between EuroSCORE and costs. The predictive accuracy for prolonged postoperative intensive care unit (ICU) stay was assessed by the Hosmer-Lemeshow goodness-of-fit test. The discriminatory power was evaluated by calculating the areas under receiver operating characteristics curves.

RESULTS

The study included 3,404 patients. The mean cost for the surgery was 7,300 dollars, in the ICU 3,746 dollars, and in the ward 3,500 dollars. Total cost was significantly correlated with EuroSCORE, with a correlation coefficient of 0.47 (p < 0.0001); the correlation coefficient was 0.31 for the surgery cost, 0.46 for the ICU cost, and 0.11 for the ward cost. The Hosmer-Lemeshow p value for EuroSCORE prediction of more than 2 days' stay in the ICU was 0.40, indicating good accuracy. The area under the receiver operating characteristics curve was 0.78. The probability of an ICU stay exceeding 2 days was more than 50% at a EuroSCORE of 14 or more.

CONCLUSIONS

In this single-institution study, the additive EuroSCORE algorithm could be used to predict ICU cost and also an ICU stay of more than 2 days after open heart surgery.

Early mortality in coronary bypass surgery: the EuroSCORE versus The Society of Thoracic Surgeons risk algorithm

BACKGROUND

We compare two widely used risk algorithms for coronary bypass surgery: The European System for Cardiac Operative Risk Evaluation (EuroSCORE) and The Society of Thoracic Surgeons (STS) risk stratification algorithm.

METHODS

Risk factors for all adult patients undergoing heart surgery at the University Hospital of Lund between 1996 and 2001 were collected prospectively at preoperative admission. Predictive accuracy for 30-day mortality was assessed by comparing the observed and the expected mortality for equal-sized quintiles of risk by using the Hosmer-Lemeshow goodness-of-fit test. The discriminatory power was evaluated by calculating the areas under receiver operating characteristics (ROC) curves.

RESULTS

The study included 4497 coronary artery bypass-only operations. The average age was 66.4 +/- 9.3 years (range 31 to 90 years). Most patients were men (77.0% versus 23.0%). The actual 30-day mortality was 1.89%. The Hosmer-Lemeshow goodness-of-fit test gave a p value of 0.81 (EuroSCORE) and 0.83 (STS), which indicates a good accuracy of both models. The area under the ROC curve was 0.84 (95% confidence interval [CI] 0.80 to 0.88) for EuroSCORE and 0.71 (95% CI 0.66 to 0.77) for STS. The discriminatory power (area under the ROC curve) was significantly larger for EuroSCORE compared with STS (p < 0.00005).

CONCLUSIONS

In this large, single institution study the additive EuroSCORE algorithm had a significantly better discriminatory power to predict 30-day mortality than the STS risk algorithm for patients undergoing coronary artery bypass.