European Journal of Cardio-thoracic Surgery 15 (1999) 816±823

Risk factors and outcome in European cardiac surgery: analysis of the
EuroSCORE multinational database of 19030 patients q
F. Roques*, S.A.M. Nashef, P. Michel, E. Gauducheau, C. de Vincentiis, E. Baudet, J. Cortina,
M. David, A. Faichney, F. Gabrielle, E. Gams, A. Harjula, M.T. Jones, P. Pinna Pintor,
R. Salamon, L. Thulin
Service de chirurgie cardiovasculaire, CHU de Fort de France, 97200 Martinique, France
Received 22 September 1998; received in revised form 8 March 1999; accepted 11 March 1999

Abstract
Objective: To assess risk factors for mortality in cardiac surgical adult patients as part of a study to develop a European System for Cardiac
Operative Risk Evaluation (EuroSCORE). Methods: From September to November 1995, information on risk factors and mortality wascollected for 19030 consecutive adult patients undergoing cardiac surgery under cardiopulmonary bypass in 128 surgical centres in eight
European states. Data were collected for 68 preoperative and 29 operative risk factors proven or believed to in¯uence hospital mortality. The
relationship between risk factors and outcome was assessed by univariate and logistic regression analysis. Results: Mean age ( ^ standard
deviation) was 62:5 ^ 10:7 (range 17±94 years) and 28% were female. Mean body mass index was 26:3 ^ 3:9. The incidence of common risk
factors was as follows: hypertension 43.6%, diabetes 16.7%, extracardiac arteriopathy 2.9%, chronic renal failure 3.5%, chronic pulmonary
disease 3.9%, previous cardiac surgery 7.3% and impaired left ventricular function 31.4%. Isolated coronary surgery accounted for 63.6% of
all procedures, and 29.8% of patients had valve operations. Overall hospital mortality was 4.8%. Coronary surgery mortality was 3.4% In theabsence of any identi®able risk factors, mortality was 0.4% for coronary surgery, 1% for mitral valve surgery, 1.1% for aortic valve surgery
and 0% for atrial septal defect repair. The following risk factors were associated with increased mortality: age (P  0:001), female gender(P  0:001), serum creatinine (P  0:001), extracardiac arteriopathy (P  0:001), chronic airway disease (P  0:006), severe neurologicaldysfunction (P  0:001), previous cardiac surgery (P  0:001), recent myocardial infarction (P  0:001), left ventricular ejection fraction(P  0:001), chronic congestive cardiac failure (P  0:001), pulmonary hypertension (P  0:001), active endocarditis (P  0:001), unstableangina (P  0:001), procedure urgency (P  0:001), critical preoperative condition (P  0:001) ventricular septal rupture (P  0:002), noncoronary surgery (P  0:001), thoracic aortic surgery (P  0:001). Conclusion: A number of risk factors contribute to cardiac surgicalmortality in Europe. This information can be used to develop a risk strati®cation system for the prediction of hospital mortality and theassessment of quality of care. q 1999 Elsevier Science B.V. All rights reserved.
Keywords: Risk factors; EuroSCORE database

1. Introduction
As a result of continually improving surgical strategy andthe technology which supports it, cardiac surgery is now
possible in an increasingly high-risk population [1]. Crude
mortality rates have often been used as an indicator of quality of care, but their value is limited without knowledge ofthe risk pro®le of the patients. Little is known about thecurrent risk pro®le of the European cardiac surgical patients.
Some European states have access to procedural cardiac
q
Presented at the 12th Annual Meeting of the European Association for
Cardio-thoracic Surgery, Brussels, Belgium, September 20±23, 1998.
* Corresponding author. Tel.: 1 596-552271; fax: 1 596-758438.
E-mail address: f.r.fwi@wanadoo.fr (F. Roques)

surgical mortality rates but these are usually not related topreoperative risk factors. We embarked on this study with aview to establish the risk pro®le of adult cardiac surgicalpatients and determine the procedural mortality in thesepatients. The large multinational database of this projectwill then serve to develop the European System for Cardiac
Operative Risk Evaluation (EuroSCORE).

2. Methods
2.1. Project setup
A multinational project steering group was set up to
include a number of European cardiac surgeons and epide-1010-7940/99/$ - see front matter q 1999 Elsevier Science B.V. All rights reserved.
PII: S10 10-7940(99)0010 6-2

F. Roques et al. / European Journal of Cardio-thoracic Surgery 15 (1999) 816±823

817

2.3. Data entry

Table 1
National patient and centre distribution aCountry

Number of centres

Number of patients

Germany
France
UK
Italy
Spain
FinlandSwedenSwitzerland
Total

23
41
15
20
25
6
1
1
132

4799
4701
3593
2846
2444
1275
245
111
20014

a
Data collection was organized separately for England (11 centres, 2774
patients) and Scotland (four centres, 819 patients).

miologists with an interest in the ®eld of cardiac surgicalrisk (Euroscore study group: Appendix A). The ®ndings ofpreliminary studies by members of the group [2,3], and thefeatures of predominantly North American risk models,
their re®nements and their application [4±14] were considered and analysed. Consequently, 68 preoperative and 29
operative risk factors were selected and de®ned on the basisof credibility, objectivity, reliability and prevalence. Theserisk factors and de®nitions are detailed in Appendices B±H.
2.2. Data collection
A simple data collection form was then designed so that
information on these risk factors could be entered easily on
one side of A4 size paper. Comprehensive information on
data collection requirements and de®nitions of variables
was provided to all participating institutions and summarized on detachable sections on every data collection form.
Mortality was de®ned as death within 30 days of operation
or within the same hospital admission (Appendix I). To
preserve con®dentiality, patient and centre identi®cation
was coded. Members of the steering committee acted asnational organizers to supervise and coordinate centre
recruitment and data collection in participating countries.
Recruitment was on a voluntary basis. Data collection was
carried out over three months (September±December 1995).
All adult patients who underwent cardiac surgery undercardiopulmonary bypass during this period were includedin the study.
Table 2
Critical preoperative conditions. These are de®ned in detail in Appendix E.
Condition

Number of patients

Percentage

Ventriculartachycardia/®brillation
IABP
Inotropic support
Cardiac massage
Tracheal intubation
Anuria

216

1.1

188
446
94
202
144

1.0
2.3
0.5
1.0
0.8

Data were gathered and entered onto a computer databaseat the biostatistical research centre of the University of
Bordeaux, France. In order to ensure the highest possible
quality of data entry, all data were entered twice independently by two operators and any discrepancies checked andcorrected. The database was subjected to 16 out-of-range
error checking operations and a further 16 separate operations were used to identify errors of logic. Incomplete forms
were identi®ed by the absence of information in any of 10
mandatory ®elds. Erroneous and incomplete data collection
forms thus identi®ed were returned to the participating
centres for correction and completion. At the end of thisprocedure, centres whose data did not reach the preset targetof . 99% for accuracy and completeness of mandatory®elds were removed from the study.
2.4. Analysis
The statistical model was multiple logistic regression.
The variables entered in the model were selected using
bivariate tests, chi square tests for categorical covariates
and unpaired t-tests or Wilcoxon rank sum tests for continuous covariates. All variables signi®cant at the P , 0:2
level were entered into the model provided they were
present in at least 2% of the sample. Non-signi®cant variables were eliminated from the model one at a time, beginning with the variable having the highest P-value. Stabilityof the model was checked every time a variable was eliminated. In the case of continuous variables where the relationship with outcome was not linear, such as serum
creatinine, we determined cut-off points using the fractional
polynomials method. When all statistically non-signi®cantvariables had been eliminated from the model, goodness-of®t testing was used to assess how well the model was calibrated and the area under the receiver operating characteristic (ROC) curve was used to assess how well the model
could discriminate between patients who lived and patients
who died.
3. Results
In all, 132 centres from 8 European countries participatedin the project, giving a total of 20014 patients. National
patient and centre distribution is detailed in Table 1. Following the error checking and quality control procedures
described above, four centres were eliminated from thestudy, leaving 19030 patients for analysis.
3.1. Patient characteristics
The mean age of the patients was 62.5 with a standard
deviation of 10.7. Age range was 17±94 years, 10% of
patients were aged 75 or over and 28% were female.
Mean body mass index was 26:3 ^ 3:9 with a range of 12

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F. Roques et al. / European Journal of Cardio-thoracic Surgery 15 (1999) 816±823

Table 3Rare preoperative conditions. These are de®ned in detail in Appendix F.
Condition

Number of patients

Percentage

Immunosuppression
Blood product refusal
Neurological disorder
Neoplasm
AIDS

80
46
266
106
4

0.4
0.2
1.4
0.6
0.02

to 68. and 5% of patients can be classi®ed as morbidly obesewith a body mass index of 33 or over. Systolic arterial bloodpressure exceeded 140 in 25% of patients and diastolicpressure exceeded 90 in 10%. A history of hypertension
was elicited from 44% of patients. Diabetes was present in
17% distributed as follows: 4% on insulin, 8.5% on oral
therapy and the rest on diet control.
3.2. Vascular disease
Evidence of extracardiac arteriopathy as de®ned inAppendix C was present in 11% of patients: 2.9% had
already undergone vascular surgery and in 1.3% such
surgery was planned for the future. Intermittent claudication
affected 5.8% of patients. Carotid disease was present in
4.4% and was bilateral in one third. Abdominal aortic
disease was present in 1.3%. There was some overlap
between the above categories because of the presence ofgeneralized arteriopathy in some patients.
3.3. Renal and respiratory function
Mean serum creatinine was 103 mmol/l with 5% of
patients exceeding 150 mmol/l. A diagnosis of chronic
renal insuf®ciency was established in 3.5% but only 0.5%
were on long-term dialysis treatment. Chronic pulmonary
disease, de®ned by the long-term use of bronchodilators andsteroids, affected 3.9% of patients.
3.4. General cardiac status
Previous cardiac surgery had been carried out in 7.2% of
patients of whom 85% had one previous operation, 10% had
two and 5% had three or more. Chronic cardiac insuf®ciency
was present in 13.7% of patients, with 5.8% in NYHA class
IV. Atrial ®brillation was present in 9%. Left ventricular(LV) function was normal in 61% of patients with an ejecTable 4
Procedural mortality overall and in the absence of any risk factors (95%con®dence intervals in brackets)tion fraction (EF) of 50% or more, moderate in 32% (EF 30±
50%) and poor in 7% (EF , 30%).
3.5. Cardiac status of coronary patients
In patients undergoing isolated coronary surgery, 15%
had a myocardial infarction within the preceding 3 months
with a mean interval of 35 days. Rest pain was present in
21% of patients and 12% were unstable to the extent ofneeding intravenous nitrate therapy. Emergency surgery
for catheter laboratory complications accounted for 1% of
all procedures. Two thirds of coronary patients had triple
vessel disease, a quarter had double vessel disease and only
8% single vessel disease. Left main stem stenosis ( . 50%)
was present in 22% of patients and very tight ( . 90%) in
5.3%.
3.6. Cardiac status of valve patients
In mitral valve surgery, the valve lesion was regurgitationin 58%, stenosis in 26% and both in 16%. Pulmonary arterysystolic pressure exceeded 60 mmHg in 16.5% of mitralpatients. In aortic valve surgery, the proportions werereversed with stenosis being the predominant lesion (55%)
over regurgitation (27%) and mixed lesions (18%). In aortic
stenosis the systolic gradient across the valve exceeded
120 mmHg in 8% of patients. Active endocarditis waspresent in 202 (3.6%) of all valve patients.
3.7. Other variables
Critical preoperative conditions affected 774 (4%) ofpatients and are summarized in Table 2. Rare conditions
which may contribute to risk were identi®ed in 737 patients(3.9%) and are detailed in Table 3.
3.8. Operations
Elective surgery accounted for 74% of procedures, with
21% and 5% being urgent or emergent as de®ned in Appendix G. Isolated coronary surgery was performed in 65% of
patients and 29.4% had valve procedures. Two thirds ofcoronary patients had three or more distal anastomoses,
25% had two and only 9% had one. Aortic valve surgery
accounted for 57% of valve procedures, mitral repair or
replacement 29% and double valve procedures 14%.
There were 489 (2.6%) operations on the thoracic aorta of
which a third involved the aortic root and 18% the aortic
arch. Atrial septal defect repair accounted for 236 procedures (1.2%) and there were 136 heart transplants.

Procedure

Overall mortality

Baseline mortality

3.9. Mortality

Isolated CABG
AVR
MVR
ASD

3.4% [3.03±3.69]
6% [5.27±6.78]
7% [5.94±8.01]
2.8% [0.57±4.99]

0.4% [0.09±0.92]
1.1% [0.36±2.56]
1% [0.21±2.92]
0% [0.00±3.97]

Overall cardiac surgical mortality for all procedures was
4.8%. Table 4 illustrates the overall procedural mortality as
well as the baseline mortality for patients without any identi®able risk factors whether signi®cant or not.

F. Roques et al. / European Journal of Cardio-thoracic Surgery 15 (1999) 816±823
Table 5Determinants of operative mortality for adult patients undergoing open
heart surgery
Variable

Odds ratio

Standard error

P valueAge (continuous)
FemaleSerum creatinine . 200
Extracardiac arteriopathy
Pulmonary disease
Neurological dysfunction
Previous cardiac surgery
Recent myocardial infarct
LVEF 30±50%
LVEF , 30%
Chronic congestive heart failure
Systolic pulmonary pressure .
60
Active endocarditis
Unstable angina
Urgent operation
Emergency operation
Critical preoperative state
Ventricular septal rupture
Non-coronary surgery
Thoracic aortic surgery

1.1
1.4
1.9
1.9
1.6
2.3
2.6
1.6
1.5
2.5
1.5
2

0.007
0.128
0.256
0.376
0.284
0.584
0.324
0.208
0.138
0.340
0.179
0.423

0.001
0.001
0.001
0.001
0.006
0.001
0.001
0.001
0.001
0.001
0.001
0.001

2.5
1.5
1.6
2.8
2.2
3.8
1.6
3.2

0.678
0.202
0.173
0.440
0.319
1.735
0.170
0.650

0.001
0.001
0.001
0.001
0.001
0.002
0.001
0.001

3.10. Risk factors analysis
Multivariate analysis identi®ed a number of risk factors to
be related to operative mortality. These are detailed in Table
5. The calibration of the model was satisfactory and thediscrimination power was very good (area under ROC
curve 0.79).

4. Discussion
The changing risk pro®le in cardiac surgical patients overthe past decade means that crude procedural mortality®gures are no longer suf®cient either for informed consent
by patients or for the assessment of the quality of care in
institutions. It is sometimes argued that crude mortality may
suf®ce for quality of care measurement as it also re¯ects thewisdom of careful patient selection. This is fallacious in
cardiac surgery because of the risk paradox: it has beenshown that it is particularly in high risk patients that thesuperiority of surgical over medical treatment is mostpronounced [15]. It is also argued by some that operative
mortality is not the only important outcome measure, thatpatients who survive cardiac operations may still have highmorbidity and a poor long-term outcome [16,17]. Although
this argument is undoubtedly true, its impact is much
weakened by the fact that both postoperative morbidity
and poor late results largely stem from failure to achieve asatisfactory cardiac outcome, itself the primary reason for
operative mortality. In other words, low early mortality islikely to be associated with low morbidity and good longterm results. Therefore, relating mortality to risk remains819

the mainstay of any system that assesses the quality ofcardiac surgical care.
There have been many studies of risk-factors in cardiac
surgery [2±14]. Most were derived from the North American patient population and may not necessarily apply toEuropean practice. This study was undertaken to produce
a reliable and contemporary European risk pro®le for
cardiac surgery. Entry to the study was voluntary. This
necessarily means that centres which agreed to participate
were self selected. We accept that this inevitably leads to adegree of bias, but the alternative approach of random selection followed by compulsion would have been associatedwith two larger problems. The ®rst is that of non-compliance leading to incomplete data collection. The second andworse problem is possible scepticism or malevolence
towards the project leading to unreliable data, wrong results
and erroneous conclusions. We believe that the excellent
compliance and high degree of data accuracy that we
obtained justi®es the voluntary enrolment approach. Accuracy and completeness were further enhanced by three
features of the study design: considerable time and effort
were invested in the preparation of a brief, user-friendly andunambiguous data collection sheet with detailed explanation at the point of use; data collection was `short andsweet' in order to avoid loss of momentum and enthusiasm
for the project over time; ®nally, patient and centre con®dentiality were guaranteed.
Many risk factors have been associated with cardiac
surgical mortality. Some are preoperative patient characteristics, others are related to the type and severity of the
cardiac disease itself and a third group are related to thetype and extent of the surgical procedure. Although therisk factors selected for evaluation were largely similar to
those in other studies, it will be noted that, whenever possible, objective and simple de®nitions were provided.
Previous studies have stumbled in ®elds which are either
naturally complex, poorly de®ned or both such as unstableangina, extracardiac arteriopathy and pulmonary disease.
We provided simpli®ed de®nitions and clear subclassi®cations in order to avoid ambiguity and the loss of potentiallyvaluable information.
This large database has for the ®rst time provided aunique opportunity to assess the true risk of cardiac surgery
in the absence of any identi®able risk factors. For the
purposes of this analysis, baseline mortality ®gures were
calculated in patients in whom no pre-operative risk factors
could be identi®ed (including risk factors which were notfound to have a signi®cant impact in this study, such as
diabetes and hypertension). When all such patients are
excluded, it was gratifying to note the extremely low current
mortality for cardiac surgery in Europe: nil for atrial septal
defect repair, 0.4% for CABG and barely over 1% for single
valve repair or replacement. Many of these `near-zero-risk'
patients with coronary disease are currently offered interventional cardiology on the alleged basis of appreciablecardiac surgical mortality. These patients and their physi-

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F. Roques et al. / European Journal of Cardio-thoracic Surgery 15 (1999) 816±823

cians may be well advised to reconsider the option of coronary surgery in the light of these results.
Many of the risk factors identi®ed as signi®cant in themultivariate analysis, such as age, sex and left ventricularfunction have been identi®ed elsewhere [2,4,13,18].The
absence of diabetes, hypertension and smoking may surprisesome clinicians but this too is supported by other studies[19±21]. Two relatively new risk factors ®gure prominently
in our ®ndings: extracardiac arteriopathy and severe neurological dysfunction. Many cardiac surgeons have learnt
from experience that these are important determinants ofoutcome, and this is supported in recent work [2,22]. We
believe that our ability convincingly to demonstrate theirimpact owes much to the simple and objective de®nitions
provided at the data collection stage. The same applies toour de®nition of chronic airway disease, a condition judged
to be too vague for inclusion by other workers [4].
The EuroSCORE database will be used to construct a risk
strati®cation system for use in all European cardiac surgery.
It is also a rich and highly accurate database, re¯ecting asnapshot of cardiac surgery in the 1990s, and will be
subjected to further analysis in order to determine demographic, regional and procedural variations in European
cardiac surgery.

(continued)
VariableDe®nition

Blood pressure(systolic anddiastolic)last preoperative value in mmHg

Appendix C. Preoperative general risk factors
VariableDe®nition

History of hypertension

Patient thinks he or she has adiagnosis of hypertension
subdivided into diet-controlled, oral
therapy or insulin
symptom presentde®ned as occlusion or . 50%
stenosisof the abdominal aorta, limb arteries
or carotids
already planned surgery of theabdominal aorta, for vascular limb
arteries or carotids
subdivided into with and without
dialysisde®ned by the long-term use of
bronchodilators or steroids

Diabetes
Intermittent claudication a
Carotid disease(unilateral orbilateral) a
Previous surgery for vasculardisease a
Future surgery disease a
Chronic renal failure

Acknowledgements

Chronic pulmonary disease

The authors wish to thank St Jude Medical and Bard fortheir ®nancial support to the EuroSCORE project. We are
grateful to Mrs Helen Rodriquez for administering the datacollection and to the European Club of Young Cardiac
Surgeons for general support in the implementation of thisventure. Finally, we wish to recognize the important effortsof the physicians and other health workers who cooperated
and contributed to the data collection in every one of the 132
participating hospitals across Europe, without whom thisproject would not have been possible.

aExtracardiac arteriopathy was de®ned as the presence of one or more ofthese four risks.

Appendix D. Preoperative cardiac risk factors
VariableDe®nition

Appendix A. EuroSCORE study group

Past cardiac operation (1, 2 ormore)

E Baudet, J Cortina, M David, A Faichney, F Gabrielle, E
Gams, E Gauducheau, A Harjula, MT Jones, P Michel,
SAM Nashef, P Pinna Pintor, F Roques, R Salamon, L
Thulin, C de Vincentiis.

Chronic congestive heart failure

any previous cardiac surgery
requiring opening the pericardium,but excluding surgery during thecurrent hospitalization
chronic or episodic peripheral
oedema, pleural effusion or
hepatomegaly
NYHA class 4

Appendix B. General patient information
VariableDe®nition

Age
Sex
WeightHeightHaematocrit
Serum creatinine

in years at last birthday
in kilogramsin centimetreslast preoperative value
last preoperative value in mmol/l

Chronic cardiac-related dyspnea
at restAtrial ®brillation
Ejection fraction
Echocardiographic shortening
fraction
Left ventricular end-diastolicpressure
Left ventricular aneurysm
Pacemaker

in mmHg
whether operated or not
permanent pacemaker in place at thetime of the operation

F. Roques et al. / European Journal of Cardio-thoracic Surgery 15 (1999) 816±823

Appendix E. Critical preoperative situation
VariableDe®nition

Ventricular tachycardia or®brillation

preoperative history of ventriculartachycardia, ®brillation or aborted
sudden death
preoperative
critical preoperative situationneeding intubation and ventilation
before arrival in the operating room
arrival of patient in the operation
room with IABP or cardiac assist
devicepreoperative
preoperative

Cardiac massage
Intubated
Intra-aortic balloon pump (IABP)
Intravenous inotropic support
Urine output , 10 ml/h(continued)
VariableDe®nition

Mitral stenosis
Systolic pulmonary arterypressure.60
Aortic regurgitation
Aortic stenosis
Aortic gradient .120 mmHg
Acute active endocarditis

for mitral surgery
for mitral surgery

VariableDe®nition

Immunosuppression

long-term immunosuppressive
therapyneurological disease severely
affecting ambulation or day-to-day
functioning
malignant tumour present at
operation
excluding HIV positive alone

Neurological dysfunction
Active neoplasm
Active AIDS
Patient refuses blood products

Number of distal coronary
anastomoses
Number of conduits
Number of mammary arteries
Number of saphenous conduits
If no mammary artery used
Mitral valve surgery
Aortic valve surgery
Tricuspid valve surgery
Ascending aortic replacement
Aortic root replacement
Aortic arch replacement

Appendix G. Indication for surgery
VariableDe®nition

Emergency

operation performed immediately onreferral to surgeon or before thebeginning of the next working day
operation performed at or after the
beginning of the next working day
but the patient must absolutely bekept in hospital before surgery
all other operations,3 months before operation, numberof days speci®ed

UrgentElective
Recent myocardial infarction
Postinfarction angina
Angina at rest
Unstable angina
Operation for catheter laboratorycomplication
Left main coronary stenosis
Number of diseased coronary
vessels
Mitral regurgitation

for aortic valve surgery
for aortic valve surgery
for aortic valve surgery
patient still under antibiotic treatment
at time of surgery; specify number ofweeks of intravenous treatment

Appendix H. Operative information
Variable

Appendix F. Rare general conditions

821

Dissection
Heart transplant
Heart±lung transplant
Atrial septal defect closure
Left ventricular aneurysmectomy
Postinfarction ventricular septal
rupture closure
Pulmonary embolectomy
Other procedure not fully
describedDe®nition

specify if operative or preoperativedecision
specify commissurotomy, repair,mechanical, bioprosthesis, homograftspecify commissurotomy, repair,mechanical, bioprosthesis, homograftspecify repair or replacement
including valve replacement andreimplantation of the coronary ostia
any operation on the thoracic aorta
needing deep hypothermic arrest or
selective cerebral perfusion
any aortic surgery for acutedissection

describe in fullAppendix I. Outcome
angina requiring intravenous nitrates
until arrival in the operating room
unplanned emergency arrival of thepatient in the operating room after acatheter laboratory procedure.50%, specify percentage
of left anterior descending,circum¯ex and right coronary
arteries, .50% stenosis or occlusion,
maximum of 3
for mitral surgery

VariableDe®nition

Alive

alive and discharged from hospital,30 days from date operation
died within 30 days from operation orlater than 30 days if still in hospitalpatient still in hospital .30 days fromoperation: hold record and ®ll in asalive or dead when appropriate

Dead
Wait

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F. Roques et al. / European Journal of Cardio-thoracic Surgery 15 (1999) 816±823

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Appendix J. Conference discussion
Dr J. Bachet (Suresnes, France): I would like to congratulate Dr Roques
for this very important work. He coordinated this study and I am sure that it
was a very dif®cult task. This is of most importance because more and more
non-medical people are dealing with this type of information and dealing
incorrectly with it. A few weeks ago in France a popular so-called `scienti®c' paper published a sort of hit parade of hospitals, and especially the
cardiac centres, with a methodology which was outrageous. The classi®cation was taking into account only the whole mortality without any group of
diseases, without scores of patients, et cetera, et cetera; it was devastating
for the public, the hospitals and moreover the patients. So I believe that thiskind of study should be sponsored by the national societies and perhaps also
by the European Association for Cardio-thoracic Surgery in order to spreadit to most centres. I understand indeed that you had 131 centres in yourstudy. I guess that this represents a very small proportion of the European
centres. Maybe through the Association we could promote this kind of
scoring into most centres in Europe.
Dr F. Grover (Denver, CO): I chair the STS National Database Committee and want to congratulate you on your risk modelling, your statisticalanalysis and your effort. As you know, in the United States we found out thehard way, about 10 years ago, just as the previous discusser mentioned,
what happens when other people analyse our data and do not risk stratify thedata so that you have a level playing ®eld. You have a problem when
governmental and other organizations publish non-risk strati®ed data. I®rmly believe in the importance of any effort that we can all make as aninternational community to risk stratify, and the importance of taking therisk of the patient into account ahead of time. It is also interesting how close
your odds ratios are for the various preoperative risk factors to ours the STS
Database.
Dr R. Dion (Brussels, Belgium): How did you select the centres and are
you planning to include more centres in your study? We would be very keen
in Belgium to participate in such a study.
Dr Roques: We chose the centres on a voluntary basis. We announced, inmost countries by mailing, that we intended to do this study and lots ofcentres answered us. But of course yesterday Sam Nashef invited everybody who wants to use this score to go on and use it and to share the study
with us. And I do agree with Mr Bachet saying that now national societies
or even the European Society should help us in this work.
Dr B. Bridgewater (Manchester, UK): Two points ®rst and then a question. We have looked at the predictive ability of some of the North American models to predict mortality following coronary artery surgery in theUK, and we found that the makeup of the population that we operate on isvery different in terms of its preoperative characteristics to the USA population, and the North American risk models are not good when you subject
them to statistical analysis. The second thing is, even within a small geographically de®ned region within the UK such as the northwest of Englandthere are very big differences in patient characteristics between the different
centres. So my question is, have you started to look in a structured way atthe differences in preoperative characteristics across the large geographicalarea which is Europe and how do you think that might in¯uence the abilityof the model to predict mortality accurately in the different areas?
Dr Roques: Well, ®rst of all, we had to analyse whether or not there were

F. Roques et al. / European Journal of Cardio-thoracic Surgery 15 (1999) 816±823
differences between North American results and European results. We havealready worked on this subject in France four years ago and the study has
been presented to you. Concerning regional particularity, of course we will
not produce 10 or 12 or 100 scores all over Europe. We have to decide touse a score that will help every one of us to work, even if it does not takecare of regional speci®cities. That is the reason why we have used an
overall score concerning coronary surgery and valve surgery, because weknow that in Europe some countries may still perform more valvularsurgery than coronary surgery. That is the reason why we chose a global
score.
Dr G. Rizzoli (Padua, Italy): The prevalence of the disease is changing
quite rapidly. For instance, in Italy now, the mitral valve operation, which
was more common among the valvular operations, has been superseded by823

the aortic valve, and the aortic is associated with coronary artery bypass. So
I would like to know if you have special rules to take care of confounding
from the prevalence of the different diseases when you prepare thesestudies?
Dr Roques: Well, we have tested every variable, we have tested 100
variables, and we decided to ®nd a score, taking care of the major problems
so as to create a global score. We considered any of the operative situations
as valve surgery and coronary surgery, but we will not answer in detail toevery speci®c problem. This is not the aim, this is not the purpose of ourwork. The purpose of the work is not to allow individual operative mortality
assessment but rather to analyse quality of care for a centre, a country, in
Europe.