CARDIOVASCULAR JOURNAL OF AFRICA • Volume 25, No 4, July/August 2014
180
AFRICA
chosen, the number of SCAs found during the run-in period
will determine the duration of monitoring in every district (and
country).
Characteristics of persons experiencing SCA will be presented
as frequencies or mean values with standard deviations.
Differences between men and women will be tested by chi-square
tests for categorical variables and
t
-tests for continuous variables.
Age- and gender-specific incidence rates of ascertained SCA will
be calculated. The counts of SCA will be used as the numerators,
and the denominators will be the population of all districts
included in the survey, as determined by the last census. The
rates will be adjusted directly to the age distribution of the total
population of each country.
Standard errors and 95% confidence intervals (CI) around
the point estimates will be calculated, assuming a Poisson
distribution. A Poisson regression model will be used to examine
the temporal trends in the incidence of SCA, with categorical
year variables and adjustment for age.
Results will be summarised by presenting the relative risk
(RR) of SCA for men and women in each year group. Logistic
regression models will be used to examine the association
between occurrence of SCA and socio-demographic and clinical
factors. In the model, year will be modelled categorically,
and a non-linear effect of age will be assessed by testing the
quadratic term. Comparison of time trends across age groups
will be accomplished by including interaction terms between
year groups and age.
A value of
p
=
0.05 will be selected for the threshold of
statistical significance, except when an interaction will be tested
for, when
p
=
0.10 will be used. All analyses will be replicated in
1 000 random samples to ensure that results are robust.
Discussion
ThePan-AfricanSCDstudyisthefirstattempttocomprehensively
characterise the SCD burden in Africa. We will collect detailed
clinical data as well as information from an electrocardiogram (if
available). Other diagnostic evaluations of SCD will also be used
where possible. We will, therefore, have a contemporary dataset
on the incidence, aetiology, patient characteristics and outcomes
of cardiac arrest in African countries.
Almost all causes of SCD have already been reported in
blacks living in Africa. However, these data are limited to case
or series reports. The PASCAR study will therefore provide a
comprehensive data on the epidemiology of SCD in this part of
the world. In line with its international outlook, the Pan-African
SCD study aims to provide an avenue for examining regional
similarities and differences in clinical features, management and
outcomes of SCA.
Strengths and study limitations
The Pan-African SCD study is a community-based, prospective
registry aimed at determining the incidence as well as prevalence
of SCD in Africa. Although the term ‘sudden cardiac death’ is
well defined clinically
7,8
and easily applicable in clinical practice,
underlying aetiologies of cardiac arrest have to be ruled out in
order to establish a more accurate epidemiological profile.
However, in the developing world, the lack of complex
and expensive cardiovascular diagnostic tools, such as exercise
ECG testing, stress echocardiography, radionuclide imaging,
coronary CT scan and coronary angiography underestimate
the ischaemic heart disease burden, which is the leading
cause of SCD in developed Western countries.
7,8,14
Also, the
underutilisation of genetic screening, diagnostic drug challenges
and electrophysiological studies in the regions where the study
will be conducted are likely to limit the identification of some
complex diagnoses, such as those of inherited arrhythmogenic
disorders, which are among the commonest causes of SCD
in young people under 35 years old.
44-46
Hence, our results will
address a global view of SCD burden rather than show the real
burden of each aetiology.
Perspectives
Expected results of this survey are aimed at understanding
whether or not SCA is a public health problem in Africa. As
preliminary reports tend to indicate, and in the light of what
is being done in Western and Asian countries,
47,48
this maiden
survey in the field of SCD in Africa will present the platform for
advocating preventive public health policies in the fight against
SCA, and also primary cardiovascular prevention in general.
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