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

CLINICAL RESEARCH European Heart Journal (2009) 30, 297–304 doi:10.1093/eurheartj/ehn581 Coronary heart disease Performance of EuroSCORE in CABG and off-pump coronary artery bypass grafting: single institution experience and meta-analysis 1 Department of Cardiac Surgery, Unit for Clinical Research in Atherothrombosis, Centro Cardiologico Monzino IRCCS, University of Milan, Via Parea, 4, 20138 Milan, Italy; Department of Radiology, MC 2026, The University of Chicago, 5841 South Maryland Avenue, Chicago, IL, USA; 3Department of Anesthesia and Intensive Care, Centro Cardiologico Monzino IRCCS, Milan, Italy; and 4Department of Cardiovascular Surgery, Clermont-Ferrand University, Clermont-Ferrand, France 2 Received 22 September 2008; revised 24 November 2008; accepted 4 December 2008; online publish-ahead-of-print 13 January 2009 Aims To assess EuroSCORE performance in predicting in-hospital mortality in on-pump coronary artery bypass grafting (CABG) and off-pump coronary artery bypass grafting (OPCAB). ..................................................................................................................................................................................... Methods Additive and logistic EuroSCORE were computed for consecutive patients undergoing CABG (n = 3440, 75%) or OPCAB (n = 1140, 25%) at our hospital from 1999 to September 2007. The areas under the receiver operating and results characteristic (ROC) curves (AUCs) were used to describe performance and accuracy. No difference in performance between CABG and OPCAB and between additive and logistic EuroSCORE (additive EuroSCORE AUCs of 0.808 and 0.779 for CABG and OPCAB, respectively; logistic EuroSCORE AUCs of 0.813 and of 0.773 for CABG and OPCAB, respectively) was found, although a marked tendency to overpredict mortality by both models was evident. A meta-analysis of previously published data was done, and a total of eight studies representing 19 212 and 5461 patients undergoing CABG and OPCAB, respectively, met inclusion criteria. Meta-analysis confirmed similar performance of EuroSCORE in CABG and OPCAB: estimated AUCs were 0.767 and 0.766 for CABG and OPCAB, respectively, with an estimated difference of 0.001 (95% CI 20.061 to 0.063). ..................................................................................................................................................................................... Conclusion Additive and logistic EuroSCORE algorithms performed similarly, and cumulative evidence suggests comparable performance in CABG and OPCAB procedures; both risk models, however, significantly overestimated mortality. ----------------------------------------------------------------------------------------------------------------------------------------------------------Keywords EuroSCORE † CABG † OPCAB † ROC analysis † Meta-analysis Introduction In-hospital mortality is frequently used as an indicator of the quality of care in cardiac surgery, and EuroSCORE has gained wide popularity among risk-stratifying tools as it has been validated with good results in European, North American, and Asiatic Institutions.1 – 8 Risk scoring systems, however, show their best performance when the pre-operative patient characteristics and treatment profiles are comparable with those on which the system was originated. For this reason, any risk scoring system can only be used reliably when its validity has been tested in the local patient * population and when surgical techniques and—more widely— patient management did not show substantial changes after the development of the risk score.9 Off-pump coronary artery bypass grafting (OPCAB) is now considered a surgical option to treat coronary artery disease; nowadays, 20 –25% of coronary bypass procedures are performed off-pump in the United States. The relatively recent introduction of OPCAB in clinical practice, which occurred sensibly after the development of currently used risk estimation models, raises the question whether these algorithms are appropriate for risk estimation in OPCAB. Corresponding author. Tel: þ39 02 580021, Fax: þ39 02 58011194, Email: Published on behalf of the European Society of Cardiology. All rights reserved. & The Author 2009. For permissions please email: . Alessandro Parolari 1*, Lorenzo L. Pesce2, Matteo Trezzi 1, Claudia Loardi 1, Samer Kassem 1, Claudio Brambillasca3, Bruno Miguel4, Elena Tremoli 1, Paolo Biglioli1, and Francesco Alamanni 1 298 A. Parolari et al. In this study, we have evaluated whether there are differences in EuroSCORE performance in estimating in-hospital mortality of patients undergoing standard coronary artery bypass surgery with the use of cardiopulmonary bypass on-pump coronary artery bypass grafting (CABG) and of patients undergoing OPCAB; this was done by first analysing our patients data and then by performing a systematic review of previously published data. Methods Single institution experience Meta-analysis To gain further insight into how EuroSCORE performs for OPCAB vs. CABG, a meta-analysis was done following the Meta-analysis Of Observational Studies in Epidemiology (MOOSE) guidelines.15 On 15 March 2008, two reviewers searched Medline (1950 to 1st week of March 2008), Embase (1966 to March 2008), PubMed (up to 15 March 2008), and The Cochrane Library including electronic links to related articles. The text string employed was the single word ‘EuroSCORE’. In order to further reduce the probability of losing any major related study an electronic search of four major cardio-thoracic surgery journals in the electronic format (Interactive CardioVascular and Thoracic Surgery, The Annals of Thoracic Surgery, The European Journal of Cardiothoracic Surgery, The Journal of Thoracic and Cardiovascular Surgery, available at http://ats.ctsnetjournals.org/search.dtl) was performed; the journals were searched from January 1999 to March 2008 for the single word ‘EuroSCORE’ in the full text of all articles. The title of every paper was considered first, then selected abstracts were searched in order to identify reports about risk prediction by EuroSCORE for coronary bypass surgery. Full text of these papers was retrieved and searched for in-hospital or 30-day mortality Figure 1 Flow chart of the meta-analysis. prediction by additive and/or logistic EuroSCORE in CABG and/or OPCAB. Figure 1 reports the flow chart of paper selection. Once papers were identified, a mandatory selection criterion for meta-analysis inclusion of each study was the presence of the assessment of discriminatory power of EuroSCORE by ROC analysis reporting the figures of merit and the dispersion parameters (standard error and/or 95% CI) necessary for the meta-analysis. Since the purpose of this meta-analysis is to gain insight into the general discriminatory characteristics of the EuroSCORE models for the two surgical modalities, we included only the area under the curve, instead of building a (...truncated)