Evaluation of the relationship between preoperative risk scores, postoperative and total length of stays and hospital costs in coronary bypass surgery

The need for cardiac surgery differential tariffs in Israel at the era of aging population and emerging technology: Importance of procedure type and patient complexity as assessed by EuroSCORE

Background

Reimbursement for cardiac surgical procedures in Israel is uniform and does not account for diversity in costs of various procedures or for diversity in patient mix. In an era of new and costly technology coupled with higher risk patients needing more complex surgery, these tariffs may not adequately reflect the true financial burden on the caregivers. In the present study we attempt to determine whether case mix and complexity of procedures significantly affect cost to justify differential tariffs.

Methods

We included all patients undergoing cardiac surgery at Shaare Zedek Medical Center between the years 1993–2016. Patients were stratified according to (1) type of surgery and (2) clinical profile as reflected by the predicted operative risk according to the European System for Cardiac Operative Risk Evaluation (EuroSCORE). Approximate cost of each group of patients was estimated by the average number of days in the Intensive Care Unit and days in the postoperative ward multiplied by the respective daily costs as determined by the Ministry of Health. We then added the fixed cost of the components used in the operating room (manpower and disposables). The final estimated cost (the outcome variable) was then evaluated as it relates to type of surgery and clinical profile. ANOVA was used to analyze cost variability between groups, and backward regression analysis to determine the respective effect of the abovementioned variables on cost. Because of non-normal distribution, both costs and lengths of stay were Log-transformed.

Results

Altogether there were 5496 patients: 3863, 836, 685 and 112 in the isolated CABG, CABG + valve, 1 valve and 2 valves replacement groups. By ANOVA, the costs in all EuroSCORE subgroups were significantly different from each other, increasing with increased EuroSCORE subgroup. Cost was also significantly different among procedure groups, increasing from simple CABG to single valve surgery to CABG + valve surgery to 2-valve surgery. In backward stepwise multiple regression analysis, both type of procedure and EuroSCORE group significantly impacted cost. ICU stay and Ward stay were significantly but weakly related while EuroSCORE subgroup was highly predictive of both ICU stay and ward stay.

Conclusions

The cost of performing heart surgery today is directly influenced by both patient profile as well as type of surgery, both of which can be quantified. Modern day technology is costly yet has become mandatory. Thus reimbursement for heart surgery should be based on differential criteria, namely clinical risk profile as well as type of surgery. Our results suggest an urgent need for design and implementation of a differential tariff model in the Israeli reimbursement system. We suggest that a model using a fixed, average price according to the type of procedure costs, in addition to a variable hospitalization cost (ICU + ward) determined by the patient EuroSCORE or EuroSCORE subgroup should enable an equitable reimbursement to hospitals, based on their case mix.

Total arterial myocardial revascularization using bilateral internal mammary arteries and the role of postoperative sternal stabilization to reduce wound infections in a large cohort study

OBJECTIVES

Total arterial myocardial revascularization using bilateral internal mammary arteries shows improved results for mortality, long-term survival and superior graft patency. It has become the standard technique according to recent guidelines. However, these patients may have an increased risk of developing sternal wound infections, especially obese patients or those with diabetes. One reason for the wound complications may be early sternum instability. This situation could be avoided by using a thorax support vest (e.g. Posthorax® vest). This retrospective study compared the wound complications after bilateral internal mammary artery grafting including the use of a Posthorax vest.

METHODS

Between April 2015 and May 2017, 1613 patients received total arterial myocardial revascularization using bilateral internal mammary artery via a median sternotomy. The Posthorax support vest was used from the second postoperative day. We compared those patients with 1667 patients operated on via the same access in the preceding 26 months. The end points were the incidence of wound infections, when the wound infection occurred and how many wound revisions were needed until wound closure.

RESULTS

The demographic data of both groups were similar. A significant advantage for the use of a thorax support vest could be seen regarding the incidence of wound infections (P = 0.036) and the length of hospital stay when a wound complication did occur (P = 0.018).

CONCLUSIONS

As seen in this retrospective study, the early perioperative use of a thorax stabilization vest, such as the Posthorax vest, can reduce the incidence of sternal wound complications significantly. Furthermore, when a wound infection occurred, and the patient returned to the hospital for wound revision, patients who were given the Posthorax vest postoperatively had a significantly shorter length of stay until wound closure.

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.

The Effect of Severity of Illness on Spine Surgery Costs Across New York State Hospitals: An Analysis of 69,831 Cases

STUDY DESIGN

Observational database review.

OBJECTIVE

To determine the effect of patient severity of illness (SOI) on the cost of spine surgery among New York state hospitals.

SUMMARY OF BACKGROUND DATA

National health care spending has risen at an unsustainable rate with musculoskeletal care, and spine surgery in particular, accounting for a significant portion of this expenditure. In an effort towards cost-containment, health care payers are exploring novel payment models some of which reward cost savings but penalize excessive spending. To mitigate risk to health care institutions, accurate cost forecasting is essential. No studies have evaluated the effect of SOI on costs within spine surgery.

MATERIALS AND METHODS

The New York State Hospital Inpatient Cost Transparency Database was reviewed to determine the costs of 69,831 hospital discharges between 2009 and 2011 comprising the 3 most commonly performed spine surgeries in the state. These costs were then analyzed in the context of the specific all patient refined diagnosis-related group (DRG) SOI modifier to determine this index's effect on overall costs.

RESULTS

Overall, hospital-reported cost increases with the patient's SOI class and patients with worse baseline health incur greater hospital costs (P<0.001). Moreover, these costs are increasingly variable for each worsening SOI class (P<0.001). This trend of increasing costs is persistent for all 3 DRGs across all 3 years studied (2009-2011), within each of the 7 New York state regions, and occurs irrespective of the hospital's teaching status or size.

CONCLUSIONS

Using the 3M all patient refined-DRG SOI index as a measure of patient's health status, a significant increase in cost for spine surgery for patients with higher SOI index was found. This study confirms the greater cost and variability of spine surgery for sicker patients and illustrates the inherent unpredictability in cost forecasting and budgeting for these same patients.

Effect of individual patient risk, centre, surgeon and anaesthetist on length of stay in hospital after cardiac surgery: Association of Cardiothoracic Anaesthesia and Critical Care (ACTACC) consecutive cases series study of 10 UK specialist centres

OBJECTIVES

To determine the relative contributions of patient risk profile, local and individual clinical practice on length of hospital stay after cardiac surgery.

DESIGN

Ten-year audit of prospectively collected consecutive cardiac surgical cases. Case-mix adjusted outcomes were analysed in models that included random effects for centre, surgeon and anaesthetist.

SETTING

UK centres providing adult cardiac surgery.

PARTICIPANTS

10 of 36 UK specialist centres agreed to provide outcomes for all major cardiac operations over 10 years. After exclusions (duplicates, cases operated by more than one consultant, deaths and procedures for which the EuroSCORE risk score for cardiac surgery is not appropriate), there were 107 038 cardiac surgical procedures between April 2002 and March 2012, conducted by 127 consultant surgeons and 190 consultant anaesthetists.

MAIN OUTCOME MEASURE

Length of stay (LOS) up to 3 months postoperatively.

RESULTS

The principal component of variation in outcomes was patient risk (represented by the EuroSCORE and remaining patient heterogeneity), accounting for 95.43% of the variation for postoperative LOS. The impact of the surgeon and centre was moderate (intra-class correlation coefficients ICC=2.79% and 1.59%, respectively), whereas the impact of the anaesthetist was negligible (ICC=0.19%). Similarly, 96.05% of the variation for prolonged LOS (>11 days) was attributable to the patient, with surgeon and centre less but still influential components (ICC=2.12% and 1.66%, respectively, 0.17% only for anaesthetists). Adjustment for year of operation resulted in minor reductions in variation attributable to surgeons (ICC=2.52% for LOS and 2.23% for prolonged LOS).

CONCLUSIONS

Patient risk profile is the primary determinant of variation in LOS, and as a result, current initiatives to reduce hospital stay by modifying consultant performance are unlikely to have a substantial impact. Therefore, substantially reducing hospital stay requires shifting away from a one-size-fits-all approach to cardiac surgery, and seeking alternative treatment options personalised to high-risk patients.

Clinical Predictions and Decisions to Perform Cardiac Surgery on High-Risk Patients

The proportion of high-risk patients undergoing cardiac surgery has increased steadily over the last two decades. Many of those patients have a catastrophic postoperative course and use hospital resources in a proportion that largely outweighs their number. Consequently, the appropriateness of invasive and intensive interventions in those patients has been questioned. If futility of care were predictable preoperatively, cardiac surgery would probably be denied to many highrisk patients. Logistic regression has been used to develop many complex predictive models to identify high-risk patients and predict their outcome; however, those models do not provide much more discrimination than clinical judgment alone. Moreover, with continuous improvement in medical care all risk models lose their calibration over time. As a result, they often overestimate the probabilities of poor outcome in the individual patients. Many high-risk cardiac surgical patients require a prolonged stay in the intensive care unit (ICU). The analysis of small cohorts of patients who had a prolonged postoperative stay in the ICU shows that 50% and 40% of them are still alive at 1- and 2-year follow-up, respectively; and most survivors report a good quality of life. Considering the limitations of predictive risk models and the satisfaction of cardiac surgical patients who survive after a prolonged ICU stay, it is reasonable to recognize that cardiac surgery should rarely be denied to high-risk patients unless technically unfeasible, and clinical predictions should have only a marginal role in the decision to operate on those patients.

Preoperative factors affecting cost and length of stay for isolated off-pump coronary artery bypass grafting: hierarchical linear model analysis

OBJECTIVE

To determine the effect of preoperative patient and hospital factors on resource use, cost and length of stay (LOS) among patients undergoing off-pump coronary artery bypass grafting (OPCAB).

DESIGN

Observational retrospective study.

SETTINGS

Data from the Japanese Administrative Database.

PARTICIPANTS

Patients who underwent isolated, elective OPCAB between April 2011 and March 2012.

PRIMARY OUTCOME MEASURES

The primary outcomes of this study were inpatient cost and LOS associated with OPCAB. A two-level hierarchical linear model was used to examine the effects of patient and hospital characteristics on inpatient costs and LOS. The independent variables were patient and hospital factors.

RESULTS

We identified 2491 patients who underwent OPCAB at 268 hospitals. The mean cost of OPCAB was $40 665 ±7774, and the mean LOS was 23.4±8.2 days. The study found that select patient factors and certain comorbidities were associated with a high cost and long LOS. A high hospital OPCAB volume was associated with a low cost (-6.6%; p=0.024) as well as a short LOS (-17.6%, p<0.001).

CONCLUSIONS

The hospital OPCAB volume is associated with efficient resource use. The findings of the present study indicate the need to focus on hospital elective OPCAB volume in Japan in order to improve cost and LOS.

Prevention of sternal wound complications after sternotomy: results of a large prospective randomized multicentre trial

OBJECTIVES

A prospective randomized multicentre trial was performed to analyse the efficacy of a vest (Posthorax support vest®) to prevent sternal wound infection after cardiac surgery, and to identify risk factors.

METHODS

From September 2007 to March 2010, 2539 patients undergoing cardiac surgery via median sternotomy were prospectively randomized into those who received a Posthorax® vest and those who did not. Patients were instructed to wear the vest postoperatively for 24 h a day for at least 6 weeks; the duration of follow-up was 90 days. Patients who did not use the vest within a period of 72 h postoperatively were regarded as study dropouts. Statistical calculations were based on an intention-to-treat (ITT) analysis. Further evaluations comprised all subgroups of patients.

RESULTS

Complete data were available for 2539 patients (age 67 ± 11years, 45% female). Of these, 1351 were randomized to receive a vest, while 1188 received no vest. No significant differences were observed between groups regarding age, gender, diabetes, body mass index, chronic obstructive pulmonary disease (COPD), renal failure, the logistic EuroSCORE and the indication for surgery. The frequency of deep wound complications (dWC: mediastinitis and sternal dehiscence) was significantly lower in vest (n = 14; 1.04%) vs non-vest (n = 27; 2.27%) patients (ITT, P < 0.01), but superficial complications did not differ between groups. Subanalysis of vest patients revealed that only 933 (Group A) wore the vest according to the protocol, while 202 (Group BR) refused to wear the vest (non-compliance) and 216 (Group BN) did not use the vest for other reasons. All dWC occurred in Groups BR (n = 7) and BN (n = 7), although these groups had the same preoperative risk profile as Group A. Postoperatively, Group BN had a prolonged intubation time, a longer stay in the intensive care unit, greater use of intra-aortic balloon pump, higher frequency of COPD and a larger percentage of patients who required prolonged surgery.

CONCLUSIONS

Consistent use of the Posthorax® vest prevented deep sternal wounds. The anticipated risk factors for wound complications did not prove to be relevant, whereas intra- and postoperative complications appear to be very significant.

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.

Risk model of prolonged intensive care unit stay in Chinese patients undergoing heart valve surgery

BACKGROUND

The aim of this study was to develop a preoperative risk prediction model and an scorecard for prolonged intensive care unit length of stay (PrlICULOS) in adult patients undergoing heart valve surgery.

METHODS

This is a retrospective observational study of collected data on 3925 consecutive patients older than 18 years, who had undergone heart valve surgery between January 2000 and December 2010. Data were randomly split into a development dataset (n=2401) and a validation dataset (n=1524). A multivariate logistic regression analysis was undertaken using the development dataset to identify independent risk factors for PrlICULOS. Performance of the model was then assessed by observed and expected rates of PrlICULOS on the development and validation dataset. Model calibration and discriminatory ability were analysed by the Hosmer-Lemeshow goodness-of-fit statistic and the area under the receiver operating characteristic (ROC) curve, respectively.

RESULTS

There were 491 patients that required PrlICULOS (12.5%). Preoperative independent predictors of PrlICULOS are shown with odds ratio as follows: (1) age, 1.4; (2) chronic obstructive pulmonary disease (COPD), 1.8; (3) atrial fibrillation, 1.4; (4) left bundle branch block, 2.7; (5) ejection fraction, 1.4; (6) left ventricle weight, 1.5; (7) New York Heart Association class III-IV, 1.8; (8) critical preoperative state, 2.0; (9) perivalvular leakage, 6.4; (10) tricuspid valve replacement, 3.8; (11) concurrent CABG, 2.8; and (12) concurrent other cardiac surgery, 1.8. The Hosmer-Lemeshow goodness-of-fit statistic was not statistically significant in both development and validation dataset (P=0.365 vs P=0.310). The ROC curve for the prediction of PrlICULOS in development and validation dataset was 0.717 and 0.700, respectively.

CONCLUSION

We developed and validated a local risk prediction model for PrlICULOS after adult heart valve surgery. This model can be used to calculate patient-specific risk with an equivalent predicted risk at our centre in future clinical practice.

Cardiac surgery risk-stratification models

Risk models are widely used to predict outcomes after cardiac surgery. Not only is risk modelling applied in the assessment of the relative impact of specific risk factors on surgical outcomes, but also in patient counselling, the selection of treatment options, comparison of postoperative results, and quality-improvement programmes. At least 19 risk-stratification models exist for open-heart surgery. The focus of risk models was originally on pre-operative prediction of mortality. However, major morbidity is in general more common than mortality and the ability to predict only operative mortality is not an adequate method of determining surgical outcome. Multiple intra- and postoperative variables have been excluded in the majority of models and the possible effect of their future inclusion remains to be seen. The unique patient population of sub-Saharan Africa requires a unique risk model that reflects the patient population and levels of care.

Clinical outcomes in patients with prolonged intensive care unit length of stay after cardiac surgical procedures

BACKGROUND

Advances in critical care medicine have allowed for improved care of patients requiring prolonged intensive care unit length of stay (prICULOS) after cardiac operations, yet little is known regarding their eventual outcomes. The purpose of this study was to examine short- and long-term outcomes in patients undergoing cardiac operations with prICULOS.

METHODS

All cases of coronary artery bypass grafting (CABG), aortic valve, mitral valve, and combined CABG/valve surgical procedures performed at a single institution from July 2002 to July 2007 were identified. All-cause mortality in patients discharged alive from the hospital was determined until December 2007 through linkage with the Social Security Death Index. Patients who experienced intraoperative death or those with missing or invalid social security numbers were excluded. The definition of prICULOS was total ICULOS greater than 7 days.

RESULTS

A total of 3,478 patients met inclusion criteria. One hundred thirty-seven of three thousand four hundred seventy-eight patients (3.9%) experienced prICULOS. These patients were more likely to be older than 70 years (55.5% versus 30.5%; p<0.0001) and to have had recent myocardial infarction (28.5% versus 20.1%; p=0.02), previous cardiac operation (18.3% versus 6.9%; p<0.0001), and emergent status (9.5% versus 1.6%; p<0.0001). They experienced greater in-hospital mortality (37.2% versus 1.7%; p<0.0001) and those who were discharged alive had worse long-term survival (log-rank, p<0.0001). After risk adjustment, prICULOS emerged as a significant predictor of in-hospital death (odds ratio [OR] 20.9; 95% confidence interval [CI], 12.9-33.7) and decreased long-term survival (hazard ratio [HR] 2.9; 95% CI, 2.0-4.3).

CONCLUSIONS

Patients with prICULOS after cardiac operations have worse overall outcomes. These data may be used to inform these patients and their families of realistic expectations regarding their clinical course.

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.

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.

Determining predictors of delayed recovery and the need for transitional cardiac rehabilitation after cardiac surgery

PURPOSE

To examine the relationship between demographic and clinical characteristics of cardiac surgery patients with postoperative length of stay (PLOS) greater than 7 days and determine the demographic, social, and clinical predictors of the need for transitional cardiac rehabilitation (TCR) after cardiac surgery.

DATA SOURCES

A retrospective review of characteristics, clinical indices, caregiver availability, and patient status (whether living alone) was completed for 304 patients undergoing cardiac surgery over 24 consecutive months. Univariate analyses and multivariable logistic regression models were used to evaluate risk factor characteristics for PLOS greater than 7 days and to predict discharge disposition to TCR or home.

CONCLUSIONS

Older patients, those with preoperative comorbidities, and those without a caregiver at home experience delays in functional recovery and discharge and are more likely to need TCR services.

IMPLICATIONS FOR PRACTICE

Our findings support the addition of functional recovery and social support risk items to the preoperative cardiac surgery risk assessment.

Preoperative calculation of risk for prolonged intensive care unit stay following coronary artery bypass grafting

Objective

Patients who have prolonged stay in intensive care unit (ICU) are associated with adverse outcomes. Such patients have cost implications and can lead to shortage of ICU beds. We aimed to develop a preoperative risk prediction tool for prolonged ICU stay following coronary artery surgery (CABG).

Methods

5,186 patients who underwent CABG between 1st April 1997 and 31st March 2002 were analysed in a development dataset. Logistic regression was used with forward stepwise technique to identify preoperative risk factors for prolonged ICU stay; defined as patients staying longer than 3 days on ICU. Variables examined included presentation history, co-morbidities, catheter and demographic details. The use of cardiopulmonary bypass (CPB) was also recorded. The prediction tool was tested on validation dataset (1197 CABG patients between 1^st April 2003 and 31^st March 2004). The area under the receiver operating characteristic (ROC) curve was calculated to assess the performance of the prediction tool.

Results

475(9.2%) patients had a prolonged ICU stay in the development dataset. Variables identified as risk factors for a prolonged ICU stay included renal dysfunction, unstable angina, poor ejection fraction, peripheral vascular disease, obesity, increasing age, smoking, diabetes, priority, hypercholesterolaemia, hypertension, and use of CPB. In the validation dataset, 8.1% patients had a prolonged ICU stay compared to 8.7% expected. The ROC curve for the development and validation datasets was 0.72 and 0.74 respectively.

Conclusion

A prediction tool has been developed which is reliable and valid. The tool is being piloted at our institution to aid resource management.

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.

Does EuroSCORE predict length of stay and specific postoperative complications after coronary artery bypass grafting?

BACKGROUND

To evaluate the performance of EuroSCORE in the prediction of in-hospital postoperative length of stay and specific major postoperative complications after coronary artery bypass grafting (CABG).

METHODS

Data on 3760 consecutive patients with CABG were prospectively collected. The EuroSCORE model (standard and logistic) was used to predict in-hospital mortality, prolonged length of stay (>12 days) and major postoperative complications (stroke, myocardial infarction, sternal infection, bleeding, sepsis and/or endocarditis, gastrointestinal complications, renal and respiratory failure). A C statistic (receiver operating characteristic curve) was used to test the discrimination of the EuroSCORE. The calibration of the model was assessed by the Hosmer-Lemeshow goodness-of-fit statistic.

RESULTS

In-hospital mortality was 2.7%, and 13.7% of patients had one or more major complications. EuroSCORE showed very good discriminatory ability in predicting renal failure (C statistic: 0.80) and good discriminatory ability in predicting in-hospital mortality (C statistic: 0.75), sepsis and/or endocarditis (C statistic: 0.72) and prolonged length of stay (C statistic: 0.71). There were no differences in terms of the discriminatory ability between standard and logistic EuroSCORE. Standard EuroSCORE showed good calibration (Hosmer-Lemeshow: P>0.05) in predicting these outcomes except for postoperative length of stay, while logistic EuroSCORE showed good calibration only in predicting renal failure.

CONCLUSIONS

EuroSCORE can be used to predict not only in-hospital mortality, for which it was originally designed, but also prolonged length of stay and specific postoperative complications such as renal failure and sepsis and/or endocarditis after CABG. These outcomes can be predicted accurately using the standard EuroSCORE which is very simple and easy in its calculation.

Risk Factors for Myocardial Injury during Off-Pump Coronary Artery Bypass Grafting

BACKGROUND

Although off-pump coronary artery bypass grafting (CABG) is now used worldwide for coronary revascularization, the pre- and intraoperative risk factors for myocardial injury associated with the surgical procedure remain to be elucidated. We performed a multivariate analysis to investigate factors that contribute to myocardial injury during off-pump CABG.

METHODS

The study population consisted of 22 patients who underwent off-pump CABG without apparent intraoperative complications. Blood samples were obtained before surgery and at 3 and 12 hours after the last anastomosis and serum Troponin T (cTnT) levels were measured to assess myocardial injury. Patient characteristics and factors related to preoperative cardiac function and the intraoperative process were analyzed to determine their correlation with serum cTnT levels, and the Spearman's correlation coefficient (r(s)) was computed.

RESULTS

Neither age, preoperative cardiac function, time required for anastomosis, the number of grafts, nor the total amount of bleeding were associated with serum cTnT levels. Serum cTnT at 3 and 12 hours after completed anastomosis correlated with the product of mean systolic blood pressure and mean heart rate (double product) during anastomosis. The r(s) values at 3 and 12 hours were 0.62 (P = .002) and 0.58 (P = .004), respectively. With respect to the serum cTnT level at 12 hours, creatinine clearance (Ccr) had a slight effect on the serum cTnT values.

CONCLUSIONS

High blood pressure and an increased heart rate during anastomosis are unfavorable factors for off-pump CABG. However, strict control of the blood pressure and heart rate makes it possible to subject even patients at high-risk to off-pump CABG from the viewpoints of myocardial injury.

Predictive value of EuroSCORE on long term outcome in cardiac surgery patients: a single institution study

OBJECTIVES

To assess the value of the European system for cardiac operative risk evaluation (EuroSCORE), a validated model for prediction of in-hospital mortality after cardiac surgery, in predicting long term event-free survival.

DESIGN AND SETTING

Single institution observational cohort study.

PATIENTS

Adult patients (n = 1230) who underwent cardiac surgery between January 2000 and August 2002.

RESULTS

Mean age was 65 (11) years and 32% were women. Type of surgery was isolated coronary artery bypass grafting in 62%, valve surgery in 23%, surgery on the thoracic aorta in 4%, and combined or other procedures in 11%. Mean EuroSCORE was 4.53 (3.16) (range 0-21); 366 were in the low (0-2), 442 in the medium (3-5), 288 in the high (6-8), and 134 in the very high risk group (> or = 9). Information on deaths or events leading to hospital admission after the index discharge was obtained from the Regional Health Database. Out of hospital deaths were identified through the National Death Index. In-hospital 30 day mortality was 2.8% (n = 34). During 2024 person-years of follow up, 44 of 1196 patients discharged alive (3.7%) died. By Cox multivariate analysis, EuroSCORE was the single best independent predictor of long term all cause mortality (hazard ratio (HR) 1.55, 95% confidence interval (CI) 1.03 to 2.34, p < 0.0001). In the time to first event analysis, 227 either died without previous events (n = 20, 9%) or were admitted to hospital for an event (n = 207, 91%). EuroSCORE (HR 1.60, 95% CI 1.36 to 1.89, p < 0.0001), the presence of > or = 2 co-morbidities versus one (HR 1.49, 95% CI 1.09 to 2.02, p < 0.0001), and > 96 hours' stay in the intensive care unit after surgery (HR 2.04, 95% CI 1.42 to 2.95, p = 0.0001) were independently associated with the combined end point of death or hospital admission after the index discharge.

CONCLUSIONS

EuroSCORE and a prolonged intensive care stay after surgery are associated with long term event-free survival and can be used to tailor long term postoperative follow up and plan resource allocation for the cardiac surgical patient.

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.

European system for cardiac operative risk evaluation predicts long-term survival in patients with coronary artery bypass grafting

OBJECTIVE

To evaluate the accuracy of predicting long-term mortality in patients with coronary artery bypass grafting (CABG) by using the European system for cardiac operative risk evaluation (EuroSCORE).

METHODS

Medical records of patients with CABG (n=3760) between January 1992 and March 2002 were retrospectively reviewed and their predicted surgical risk was calculated according to the standard (study A) and logistic (study B) EuroSCORE. In study A the patients were divided into six groups: 0-2 (n=610), 3-5 (n=1479), 6-8 (n=1099), 9-11 (n=452), 12-14 (n=103) and >14 (n=17). In study B the patients were divided into seven groups: 0.00-2.00 (n=447), 2.01-5.00 (n=1190), 5.01-10.00 (n=890), 10.01-20.00 (n=686), 20.01-30.00 (n=234), 30.01-60.00 (n=254) and >60.00 (n=59). Long-term survival was obtained by the National Death Index and Kaplan-Meier curves were constructed and compared employing the log-rank test. Multivariate Cox regression analysis was performed in order to control for pre, intra and postoperative factors and adjusted hazard ratios were calculated for standard and logistic EuroSCORE groups. The receiver operating characteristic (ROC) curves were plotted to assess the discrimination ability of the EuroSCORE.

RESULTS

In study A there were differences among the six groups in 30-day mortality (0.7%, 1.0%, 3.1%, 4.6%, 13.6% and 23.5%; P<0.001), in major complications (8.5%, 10.4%, 16.2%, 20.4%, 31.1% and 35.3%; P<0.001) as well as in actuarial long-term survival (86.2%, 79.6%, 53.6%, 37.9%, 24.9% and 0% from EuroSCORE 0-2 to >14; P<0.001). In study B there were differences among the seven groups in 30-day mortality (0.9%, 1.1%, 1.2%, 3.6%, 3.4%, 8.7% and 15.3%; P<0.001), major complications (8.5%, 10.1%, 12.1%, 18.4%, 16.2%, 26.0% and 30.5%; P<0.001) as well as in actuarial long-term survival (89.5%, 79.9%, 66.9%, 51.0%, 40.3%, 38.4% and 13.7% from EuroSCORE 0.00-2.00 to >60.00; P<0.001). Multivariate Cox regression analysis confirmed that EuroSCORE (standard or logistic) was a statistically significant predictor for long-term mortality, while the area under the ROC curve was 0.72 for either standard or logistic EuroSCORE.

CONCLUSION

The predicted surgical risk in CABG patients as calculated by standard or logistic EuroSCORE is a strong predictor for long-term survival in addition to predicting operative survival for which it was originally designed.

Emergency and elective coronary artery bypass grafting: comparisons of risk profiles, postoperative outcomes, and resource requirements

OBJECTIVE

To investigate the association between preoperative risk factors and postoperative outcomes in emergency and elective coronary artery bypass graft (CABG) patients and to quantify resource requirements.

DESIGN

Retrospective database review.

SETTING

New York State SPARCS database.

PARTICIPANTS

Data from 4,001 emergency and 7,489 elective CABG patients were evaluated retrospectively.

INTERVENTIONS

Data were compared between groups using chi-squares, t tests, and logistic regression analysis.

MEASUREMENTS AND MAIN RESULTS

Preoperatively, 47.1% of patients in the emergency group had unstable angina and 34.1% had acute myocardial infarction compared with 33.9% and 15.2% in the elective group, respectively (p < 0.0001). There were no marked differences in the preoperative noncardiac risk factors between groups. The mortality rate was 4.7% in the emergency group and 2.6% in the elective group (p < 0.0001). The emergency group had more postoperative cardiac complications (18.3% v 8.3%, p < 0.0001). The length of hospital stay in the emergency group was 17.5 +/- 15.8 days (median 14 days) compared with 12.9 +/- 15.1 days (median 9 days) in the elective group (p < 0.00001). Total hospital charges in the emergency and elective groups were 46,700 US dollars +/- 42,400 US dollars (median 35,600 US dollars ) and 34,800 US dollars +/- 36,400 US dollars (median 26,500 US dollars) (p < 0.00001), respectively. The median total cost was 26,300 US dollars for emergency and 19,600 US dollars for elective group (p < 0.00001).

CONCLUSION

Patients undergoing emergency CABG had greater postoperative morbidity and mortality, longer LOS, and higher total costs than patients undergoing elective surgery. This difference is predictable on the basis of preoperative cardiac risk factors. Emergency operations have a major impact on the rates of morbidity, mortality, and use of resources.

[Results of isolated and combined surgical coronary revascularization in patients over 75]

BACKGROUND

Increase in life expectancy is causing an increase of surgical myocardial revascularization procedures in the elderly. We evaluate the evolution of this type of interventions in people older than 75 years, taking into account the risk factors, results and survival.

PATIENTS AND METHOD

Between July 1988 and May 2001, 237 isolated or combined myocardial revascularization procedures were carried out in patients older than 75 years (Group I), while 1177 were performed in younger patients (Group II). We retrospectively analyzed the mortality risk factors, surgical procedures, postoperative complications and survival in Group I patients.

RESULTS

Preoperatively, Group I patients showed a more frequent left ventricular dysfunction, left main coronary stenosis, emergency surgery and combined procedures, while Group II patients displayed more common preoperative myocardial infarction and dyslipemia. Mortality in Group I was 20.7% vs 9.09% in Group II. Mortality was higher for mixed procedures (27.1%) than for isolated myocardial revascularization (13.8%). Postoperative complications were present in 48.5% patients. Significant preoperative risk factors of mortality in Group I were: female sex, high-risk ergometry, III-IV NYHA functional class, and atrial arrhythmia. The preoperative NYHA functional class was also a morbidity risk factor. Survival at 1, 3 and 5 years was present in 98.4%, 92.1% and 81% patients, respectively, NYHA functional class I-II being present in 94.18% patients.

CONCLUSIONS

Myocardial revascularization surgery in people older than 75 years leads to an increase of morbimortality. Anyway, long-term survivors' quality of life makes us think of surgery as a valid treatment alternative.

Validation of a preoperative risk index as a predictor of perioperative morbidity and hospital costs in coronary artery bypass graft surgery

OBJECTIVE

To validate a previously developed model (CABDEAL) for predicting postoperative morbidity for coronary artery bypass graft (CABG) surgery patients using the New York State Statewide Planning and Research Cooperative System (SPARCS) database and to examine the effects of preoperative risk factors, postoperative complications, and death on costs of care for CABG surgery.

DESIGN

Retrospective database review.

SETTING

Governmental agency database of cardiac surgery.

PARTICIPANTS

CABG surgery patients (n = 15,388).

INTERVENTIONS

A previously developed preoperative risk model (CABDEAL) was applied to all patients. Predicted length of hospital stay and costs were compared with actual length of stay and costs, using a charge-to-cost conversion formula.

MEASUREMENTS AND MAIN RESULTS

The CABDEAL model was moderately predictive of outcomes. The specificity was 64%, the sensitivity was 73.8%, and the receiver operating characteristic curve area was 0.728. Morbidity in the form of postoperative complications was recorded in 24.5% (3,770 patients), and the mortality rate was 3.4% (527 patients). The mean (+/- SD) total hospital cost was 28,408 US dollars +/-28,982, and the median cost was 21,644 US dollars. Based on the linear regression model, an equation was developed for predicting total costs: Cost (in US dollars) = 22,952 + (3,277. [CABDEAL score]).

CONCLUSION

The previously developed CABDEAL model was predictive of increased morbidity in the SPARCS database. Total hospital costs increased nearly linearly with increasing CABDEAL score. These results encourage the development of models for preoperative estimation of costs related to perioperative morbidity.