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8
Giornale Italiano di Cardiologia Pratica
It J Practice Cardiol
Ottobre 2003
From time immemorial, up to the present
day, man has always desired the knowledge
of what his own future holds - his health
and illnesses, amorous conquests, business
and war.
According to the Ancient Romans, the ability
to see into the future (divinatio) was considered
a gift from the gods, like Apollo’s gift to
Cassandra in the conquering of her love, and
Zeus to Tiresias to compensate for his blindness.
(Homer’s Odyssey; Ovidio’s Metamorphosis).
But according to the ancients, very
few mortals were granted the priviledge of
knowing their own and others’ destiny, which
on the other hand was predetermined in ancient
religions, as it is still today in Judaism
and Calvinism. There is no space for the concept
of predestination in today’s scientific and
secular culture. A new truth has appeared,
however, as regards predestination – that of
genetics, whose knowledge belongs to those
who jealously guard against the intrusion of
the Life Insurance Companies.
In the Greco-Roman society for many centuries,
the theory of predestination, or each
person’s “fate”, nourished the services
which were destined to discover it. These
were entrusted not only to the prophets
and to the great organizations like Delphi,
but to other – let’s say – specialists in the
different techniques, which were based on
a general method according to which, to
use the words of Cicero (De Divinatione, 1-
7): “ the prophetic signs are observed and
recorded in coincidence with what takes
place through the action of... haruspexes,
omens and other “interpretations”.
Even today, for our predictions, we go by
information gathered in the so-called “observational”
studies and to their association
with events. But, unlike the past, thanks to
modern scientific methodology and statistic
analysis, we are able to distinguish whether
the coincidences or associations are incidental
or causal.
Since many decades, the interest of the
scientific medical and surgical community
about the prediction of risks associated to
the different characteristics of populations is
risen, especially as to cardiovascular diseases
and tumours.
Among all the heart diseases cares, cardiac
surgery is the most complex, risky and expensive.
Nowadays, this is the reason why patients,
cardiologists, cardiac surgeons, hospital
administrations and quality assurance ser-
vices are interested to know the operating
risk, generally understood like mortality risk.
In fact, operative mortality is widely used to
assess the Quality of care in cardiac surgery.
However it is well known that the crude
mortality rate at different levels of aggregation
(surgeon, single centre and as a mean
of more centres of a geographic or administrative
region expressed by the rate of inhospital
deaths vs all operated patients) does
not take into account the severity of patients
condition that can adversely affect survival
during and early after surgery. For this reason
the crude mortality rate can be viewed
as misleading measure of quality of care.
The belief that for a quality evaluation of
cardiac surgery outcome it is necessary to
stratify patients according to the risk of adverse
events has become evident within the
scientific community of heart surgeons and
health administrations of the western world
over the past 20 years.
All risk stratification models (there are over
20 models even though less than ten of
them are extensively used (1) [Table 1]) have
been developed by selecting the factors
significantly associated with mortality risk
and more recently with other types of risk.
These factors were selected out of several
dozens of demographical, clinical and angiographical
variables. For example in the
Society of Thoracic Surgeons model (2),
only 28 independent and significant variables
were selected out of the 100 included
in the preliminary analysis; Parsonnet (3)
and the Euroscore (4) included respectively
into the model only 15 and 17 of the 40 different
variables studied.
Since those models were developed several
years ago they were periodically updated
and recalibrated as the STS, the Parsonnet,
Hannan and o’Connor.
This is the reason why as long as clinical
and epidemiological scenarios and heart
surgery technology are evolving, the possibility
of discovering a significant association
among the preoperative characteristics of
the patients, quality heart surgeons, and
quality of cardiac surgery units, as well as
the short and middle term outcomes, is linked
to the availability of databases that are
complete and specific for the type of surgery,
regularly checked and updated. In
fact, when, on the same population, an old
risk model, a risk recalibrated model and a
risk model especially updated with new risk