CARDIOVASCULAR JOURNAL OF AFRICA • Vol 21, No 1, January/February 2010
AFRICA
13
Cardiovascular Topics
Tracking of lipids in schoolchildren: a four-year follow-
up, population-based study in Sousse (Tunisia)
I HARRABI, J MAATOUG, R. GAHA, K LIMAM, AS ESSOUSSI, H GHANNEM
Summary
Objective:
Dyslipidaemia, which is now seen as one of the
most important cardiovascular risk factors, is becoming more
common in the younger population. The aim of this study was
to assess the efficacy of tracking serum lipid levels over a
four-year period in an urban population of schoolchildren.
Methods:
The study began in 1999 with a cohort of 789
schoolchildren. Four years later this group was resurveyed
and a further 452 adolescent were recruited to the study.
Results:
The percentages of boys who were initially in the
extreme quartile for total cholesterol (TC), low-density lipo-
protein (LDL) cholesterol and triglycerides were 42.5, 54.8
and 40.4%, respectively. Similarly, the percentages of girls in
the extreme quartile were 62.7, 53.8 and 38.2%. Four years
later, both the boys and girls were still in the extreme quartile
for these parameters. Therefore, the best predictor of follow-
up level for each of the serum lipoprotein cholesterol frac-
tions was the corresponding baseline level. Interestingly, the
next best predictor in most of the groups was change in body
mass index (
Δ
BMI) and smoking status.
Conclusion:
Prevention of coronary heart diseases in adults
must begin early on in childhood, and should be driven by
health education towards achieving a healthy lifestyle.
Keywords:
lipids, tracking, adolescent, epidemiology
Submitted 20/2/09, accepted 9/6/09
Cardiovasc J Afr
2010;
21
: 13–16
The World Health Organisation (WHO) has helped avert 16.7
million deaths due to cardiovascular diseases by promoting
healthy diet and lifestyle.
1
Cardiovascular disease is the major
cause of morbidity and mortality in most industrialised coun-
tries.
2
Tunisia is now facing the phenomenon of an epidemio-
logical transition, with an increase in chronic non-communicable
diseases, particularly cardiovascular disease.
3
Dyslipidaemia is
seen as the major cardiovascular risk factor and it is becoming
more prevalent among the young population.
4,5
It has been estab-
lished that atherosclerosis is a process that starts in childhood.
6-9
The Bogalusa heart study identified a strong association of
total cholesterol and low-density lipoprotein cholesterol with
cholesterol found in the aortic and coronary vessels at post
mortem.
10,11
The tendency for an individual to maintain his/her
level of disease risk factor relative to his/her peers through time
has important implications in terms of determination of causality
of disease, as well as for the prevention of future related morbid-
ity and mortality.
12
Several longitudinal studies have reported
significant tracking of serum lipid levels from childhood to
adulthood.
13-15
In Tunisia there have not been any longitudinal
studies on the tracking of serum lipid levels in children and
adolescents. The only available data at the population level are
from a study on baseline serum lipid levels in children.
16,17
The purpose of this study was to track serum lipid levels over
a four-year period in an urban population of schoolchildren.
Methods
This prospective study was based on a survey of a cohort of
schoolchildren aged 13 to 15 years. A similar study on subjects
aged 17 to 19 years has been described in detail elsewhere.
18
Our
study began in 1999 with a cohort of 789 schoolchildren. Four
years later this group was resurveyed and a further 452 adoles-
cent were recruited to the study.
Data were collected anonymously using a self-administered
questionnaire during a class session, with the collaboration of
teachers and parents. All participants completed a questionnaire
on their family history of cardiovascular disease, such as hyper-
tension, and lifestyle characteristics including smoking, usual
physical activity and dietary intake.
Research technicians recorded body weight to the nearest 0.1
kg using a standard beam balance scale with subjects barefoot
and wearing light indoor clothing. Body height was recorded to
the nearest 0.5 cm. Body mass index (BMI) was defined accord-
ing to the Cole criterion.
19
Taking into account the risk of bias due to observation, we
opted for the electronic system to measure blood pressure. The
reproducibility of measurements and the precision of this device
has been demonstrated.
20,21
After a 10-minute rest, we measured
blood pressure on the right arm in the seated position, using an
appropriate cuff size. We measured the blood pressure again after
a 15-minute rest and the average was used in the analysis.
Participating children had to fast for 12 hours before blood
was taken. Breakfast was served thereafter. A trained nurse with
Service d’Epidémiologie et des Statistiques Médicales, CHU
F Hached, Sousse, Tunisia
I HARRABI, MD,
J MAATOUG, MD
R GAHA, MD
H GHANNEM, MD
Département de Biochimie , Faculté de Médecine de
Sousse, Sousse, Tunisia
K LIMAM, MD
Service de Pédiatrie, CHU F Hached, Sousse, Tunisia
AS ESSOUSSI, MD
