CARDIOVASCULAR JOURNAL OF AFRICA • Vol 21, No 5, September/October 2010
AFRICA
263
Risk factors associated with intermediate and long-term
mortality following vascular surgery in South African
patients
BM BICCARD, S NEPAUL
Summary
There are few data on predictors of mortality following
vascular surgery in South African patients. While in the
developed world, peri-operative risk factors are also associ-
ated with intermediate-term survival, it is likely that the
weighting and even the clinical risk factors may be differ-
ent in South African patients due to the epidemiology of
cardiovascular disease in developing countries. The aim of
this study was therefore to determine risk factors associated
with intermediate and long-term mortality in South African
vascular surgical patients.
Design:
A retrospective cohort study was conducted.
Intermediate and long-term survival was determined by
subsequent hospital visits or admissions. For patients who
did not return to the hospital, the patient or patient’s next of
kin was contacted telephonically. The outcome of the patient,
and the time to the outcome following the surgical proce-
dure were recorded. Bivariate and multivariate analysis was
conducted using Cox regression analysis to determine predic-
tors of intermediate-term mortality.
Results:
Only hypertension and diabetes were associated
with intermediate and long-term mortality at the bivari-
ate level of analysis with
p
<
0.10. There was no co-linear-
ity between hypertension and diabetes. Hypertension was
the only predictor of intermediate and long-term survival
retained in the multivariate model (hazard ratio 3.86, 95%
confidence interval 0.83–15.4,
p
=
0.086).
Conclusion:
In contrast to developed-world observations,
peri-operative clinical risk indices were not associated with
intermediate and long-term survival in South African vascu-
lar surgical patients. Instead, two risk factors that were iden-
tified in the South African National Burden of Disease study
were associated with mortality. It appears that a ‘western
lifestyle’ (and the presence of associated risk factors) may be
more important predictors of intermediate and long-term
mortality than peri-operative risk predictors of cardiac
events in SouthAfrican vascular surgical patients. This study
highlights an important public health issue for the South
African population where the most important determinants
of mortality are continued exposure to risk factors (such
as hypertension and diabetes) in the community, with little
modification of these risk factors through primary health
surveillance and management, even after surgical admission
for pathology known to be associated with these risk factors.
Submitted 3/9/09, accepted 10/3/10
Cardiovasc J Afr
2010;
21
: 263–267
DOI: CVJ-21.004
There is a paucity of data on predictors of cardiac mortality and
all-cause mortality following vascular surgery in South African
patients. This is a concern that the weighting and even the
clinical risk factors may be different in South African patients
in comparison to developed-world patients.
1
In an attempt to
address this situation, we have used an established vascular
surgical database at Inkosi Albert Luthuli Central Hospital
(IALCH) to determine risk factors associated with in-hospital
cardiac
2
and all-cause mortality.
3
There are few data of intermediate (less than one year follow-
ing surgery)
4
and long-term (more than one year following
surgery)
4
outcomes following vascular surgery in South African
patients. A study of femoral–distal bypass conducted between
1999 and 2002 in Cape Town showed a two-year mortality of
19.2%, but was too small to determine independent predictors
of mortality.
5
A long-term model of all-cause mortality following peripher-
al arterial surgery has been developed in a first-world population
(Rotterdam study).
6
Listed in decreasing order of importance,
this study showed that one-year mortality was associated with an
age above 65 years, renal dysfunction, hypercholesterolaemia, a
history of congestive heart failure, an ankle-brachial index of
<
0.60, Q-waves on ECG and diabetes.
6
Therefore, five of the six clinical risk factors of Lee’s Revised
Cardiac Risk Index (which are independent predictors of peri-
operative cardiac events following non-cardiac surgery)
7
were
also independent predictors of one-year mortality.
6
Indeed, the
five-year mortality model
6
included all of Lee’s clinical risk
predictors.
7
Therefore in a developed-world population, predic-
tors of peri-operative cardiac events also appear to be predictors
of intermediate and long-term mortality following vascular
surgery.
The Rotterdam study is, however, probably of limited use in
the South African population. This may be reflected in the differ-
ence in survival rates between the two studies. The one- and five-
year mortality rate was 6 and 22%, respectively, in the Rotterdam
study,
6
which is lower than that reported in the Cape Town study
of 19% at two years.
5
The difference in long-term outcome reported between the
Cape Town and Rotterdam studies may reflect differences in the
Department of Anaesthetics, Nelson R Mandela School
of Medicine, and Inkosi Albert Luthuli Central Hospital,
Durban, South Africa
BM BICCARD, MB ChB, FCA (SA), FFARCSI, MMedSc, PhD,
Department of Clinical Technology, Durban University of
Technology, Durban, South Africa
S NEPAUL, BTech (Clin Technol Crit Care)
