CARDIOVASCULAR JOURNAL OF AFRICA • Vol 23, No 3, April 2012
AFRICA
161
multiple cardiac procedures, include the European System for
Cardiac Operative Risk Evaluation (EuroSCORE), the Society of
Thoracic Surgeons (STS) algorithms, and the Parsonnet score.
1
These will be briefly discussed.
The European System for Cardiac Operative Risk
Evaluation
Combining the most important pre-operative risk factors, the
EuroSCORE method has been shown to be a valuable measure
for prediction of immediate death after adult cardiac surgery.
9
It
has been studied widely and is believed by many to be the gold
standard.
1
The clinical aim of the logistic EuroSCORE was to construct
a scoring system predicting early mortality in cardiac surgical
patients in Europe on the basis of objective risk factors.
3
It
was developed from a large European database and eventually
included 13 302 patients.
3
Prospective data collection took place
in eight European countries between September and December
of 1995.
10
The EuroSCORE provides two methods for calculating
predicted outcome: the additive model and the logistic model.
3
Validation of the EuroSCORE took place all over the world in
a variety of population settings.
1,11,12
The logistic EuroSCORE
uses logistic regression and the risk has to be calculated in a
very complex way. The simpler additive model was derived from
the full logistic model by approximating the odds ratios (OR) or
modified coefficients from the logistic equation with integers,
which can then be added together at the bedside to provide a
useful estimate of risk in an individual patient.
13,14
Although well established and validated in patient populations,
the additive EuroSCORE sometimes underestimates the risk
when certain combinations of risk factors co-exist.
14
The logistic
EuroSCORE on the other hand, has been reported by various
centres to over-predict risk despite gradual worsening of the
risk profiles of patients and the improvement in cardiac surgical
outcomes observed.
15
Although the additive model is easier to
use, the logistic EuroSCORE has been reported to have a better
risk-predictor ability, especially in high-risk patient groups.
16,17
The logistic EuroSCORE lacks the prediction of possible
morbidity and does not include any intra-operative variables.
Evidence that the EuroSCORE might be out of date led to the
collection of new data to enable re-evaluation. Data collection
started early in 2010. It was estimated that if enough centres
participated, data collection would only take three weeks, but the
longest period asked for would be three months.
18
The Society of Thoracic Surgeons Algorithms
The Society of Thoracic Surgeons National Cardiac Database
(STS NCD) was created in 1989 and it has become the
largest clinical database of its kind. The primary aim for the
development of the STS model was the support of national
quality-improvement programmes. Now it is also used for
TABLE 1. A SUMMARY OF CARDIAC SURGERY RISK-STRATIFICATION MODELS
4,31
(WITH PERMISSION)
Model
Region
Year of data
collection
Year of publication
Number of patients
(centres)
Risk variables
Amphiascore
Netherlands
1997
-
2001
2003
7 282 (1)
8
Cabdeal
Finland
1990
-
1991
1996
386 (1)
7
Cleveland Clinic
USA
1986
-
1988
1992
5 051 (1)
13
EuroSCORE (additive)
Europe
1995
1999
13 302 (128)
17
EuroSCORE (logistic)
Europe
1995
1999
13 302 (128)
17
French score
France
1993
1995
7 181 (42)
13
Magovern
USA
1991
-
1992
1996
1 567 (1)
18
NYS
USA
1998
2001
18 814 (33)
14
NNE
USA
1996
-
1998
1999
7 290 (N/A)
8
Ontario
Canada
1991
-
1993
1995
6 213 (9)
6
Parsonnet
USA
1982
-
1987
1989
3 500 (1)
16
Parsonnet (modified)
France
1992
-
1993
1997
6 649 (42)
41
Pons
Spain
1994
1997
1 309 (7)
11
STS risk calculator*
isolated CABG
valve procedures
CABG and valve
USA
2002–2006
2007
774 881 (819)
109 759
101 661
49
50
50
Toronto
Canada
1993
-
1996
1999
7 491 (2)
9
Toronto (modified)
Canada
1996
-
1997
2000
1 904 (1)
9
Tremblay
Canada
1989
-
1990
1993
2 029 (1)
8
Tuman
USA
N/A
1992
3 156 (1)
10
UK national score
UK
1995
-
1996
1998
1 774 (2)
19
Veterans Affairs
USA
1987
-
1990
1993
12 712 (43)
10
USA = United States of America, EuroSCORE = European System for Cardiac Operative Risk Evaluation, NYS = NewYork State, NNE = North-
ern New England, STS = Society of Thoracic Surgeons, CABG = coronary artery bypass graft surgery, UK = United Kingdom.
*The STS risk calculator consists of seven risk-prediction models in three main categories, namely isolated CABG, valve procedures, and
combined CABG and valve procedures. Data represented for the STS risk calculator reflect the number of patients and risk variables captured in
the database used for the latest models developed (version 2.61).
