37 / 48
SA JOURNAL OF DIABETES & VASCULAR DISEASE
RESEARCH ARTICLE
VOLUME 14 NUMBER 2 • DECEMBER 2017
75
in Tessekere, a rural municipality in northern Senegal, and to analyse
trends in obesity in Dakar; (2) to determine sociodemographic risk
factors for obesity in both environments; and (3) to compare ideal
body size between urban and rural areas.
Methods
The study was approved by the National Ethics Committee for
Health Research of Senegal (protocol SEN13/67, no 0272). The
research was conducted in accordance with the Declaration
of Helsinki, and written informed consent was obtained from
participants.
This study was conducted from February to August 2015 on a
sample of 1 000 individuals, aged 20 years and older in Dakar, and
on a sample of 500 adults of the same age bracket in the Tessekere
municipality. The samples were constructed using the combined
quota method (cross-section by age, gender and town of residence
in Dakar; only by age and gender in Tessekere municipality) in
order to strive for representativeness of the population aged 20
years and older living in the department of Dakar and in Tessekere
municipality. Data from the Agence Nationale de la Statistique
et de la Démographie dating from the last census (2013) were
used.
The quota variables used were gender (male/female), age
(20–29, 30–39, 40–49, 50–59, and 60 years and over, with an
upper age limit of 100 years) and, for Dakar, town of residence.
In Dakar, the towns were grouped by the four arrondissements
making up the department: Plateau-Gorée (five towns), Grand
Dakar (six towns), Parcelles Assainies (four towns) and Almadies
(four towns). In practical terms, this method requires constructing
a sample that reflects the proportions observed in each target
population. For example, according to the last census, men
aged 20–29 years living in the town of Medina (arrondissement
of Plateau-Gorée) represented 1.9% of the population aged 20
years and over living in the department of Dakar. The sample was
constructed to reflect this proportion and it included 19 men aged
20–29 living in this town.
Inclusion criteria were individuals 20 years old or older, living in
the department of Dakar. Pregnant women were excluded from
the study.
Eight trained investigators (PhD students in Medicine,
Pharmacy and Sociology) started out each day from different
points in each town (Dakar) or camp (Tessekere) to interview
individuals in Wolof, Haalpulaar or French in every third home.
Investigators had a certain number of individuals to interview to
meet the quotas. Only one person was selected as a respondent
in each home. Investigators went to the house, inquired about the
inhabitants and then chose the first person they saw who met the
characteristics needed for the quotas. In-person interviews were
conducted. They ranged from 45 minutes to more than one hour
and 30 minutes, depending on respondent availability and desire
to talk.
Weight was measured using a digital scale (measurement
accuracy of 100 g), with subjects dressed in minimal clothing
and barefoot. To measure height, the subject was to stand ‘at
attention’, arms at the sides, heels together, without shoes.
Following World Health Organisation (WHO) recommendations,
BMI was calculated by dividing the weight (kg) by the square of
the height (m
2
). Underweight was defined as BMI < 18.5 kg/m
2
;
overweight was defined as 25 ≤ BMI < 30 kg/m
2
; and obesity
corresponded to a BMI of ≥ 30 kg/m
2
.
26
Waist circumference (WC) was measured at the narrowest
point of the abdomen at the end of a normal expiration. WC was
measured using a measuring tape with 1-mm accuracy. WC of
≥ 102 cm in men and ≥ 88 cm in women was considered central
obesity.
27
Waist-to-hip ratio (WHR) was also used as a criterion of
central obesity: a WHR of ≥ 0.9 in men and ≥ 0.8 in women was
considered central obesity.
28
Among the sociodemographic data collected during the
interviews, three variables were taken into account for this study:
age, gender and educational level. Four age groups were defined:
20–29, 30–39, 40–49 and 50 years and over. Gender was coded as
follows: 1 for women, 0 for men. In Dakar, five levels of education
were defined based on the Senegalese school system: none, primary
(one to five years of schooling), intermediate (six to eight years),
secondary (nine to 12 years), and university (13 years and over). In
the Tessekere municipality, given the large proportion of persons
who have never attended school (76%), the educational level was
dichotomised: no schooling/one or more years of schooling.
Satisfaction with body weight was assessed in one question,
with five possible responses: ‘Do you think you are: too thin, a little
too thin, average, a little too fat, too fat?’ To determine ideal body
size, we took the BMI at which the same percentage of individuals
believed they were too heavy as those who felt they were too
thin.
29
We also used the body size scale (BSS), developed and validated
by Cohen
et al
. in Senegal,
30
to assess ideal body size (IBS) of
women and men, to obtain a complementary representation of
body image assessed from the questionnaire. This tool has two
advantages: (1) it consists of a gender-specific scale of nine models;
and (2) it represents real black models with their anthropometric
characteristics to assess specific body weight perceptions in African
populations. One model represents the underweight category, three
models the normal-weight category, two models the overweight
category, and one model each class of obesity level as defined by
the WHO (30.0 < BMI ≤ 34.9 kg/m², 35.0 < BMI ≤ 39.9 kg/m²,
and ≥ 40 kg/m²). BSS was considered a numerical variable, as each
human picture ranged from 1 to 9 according to increasing BMI
categories to measure ideal body size.
Statistical analysis
To answer our research questions, we used the Student’s
t
-test,
ANOVA, chi-squared test and logistic regressions. Results are
expressed as mean ± standard deviation for continuous variables
or as percentages for categorical variables. Bivariate comparisons
were performed using the Student’s
t
-test, ANOVA for continuous
variables, and chi-squared tests for categorical variables. Multivariate
analyses were performed using binary logistic regression and results
are expressed as odds ratios with 95% confidence intervals (CIs).
The software used for the statistical analysis was SPSS Statistics 22
for Windows.
Results
Among the 1 000 individuals included in the Dakar sample,
16 women were excluded because they reported pregnancy.
Similarly, four women of the Tessekere sample were also excluded
for pregnancy. Analyses were finally performed on a sample of
984 Dakarites and 496 Tessekere dwellers. The distributions of
height, weight, BMI, WC, WHR, general and central obesity,