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RESEARCH ARTICLE
SA JOURNAL OF DIABETES & VASCULAR DISEASE
14
VOLUME 15 NUMBER 1 • JULY 2018
and a study of 421 subjects from a rural community of Angola
(2.8% prevalence of diabetes).
17
Building on the work carried out by Pires and colleagues,
16
and
based on the STEPS methodology,
11
this study aimed to expand the
sample population to the 15- to 24-year-old group, and to estimate
the prevalence, awareness, treatment and control of hypertension,
diabetes and hypercholesterolaemia, and its association with
sociodemographic (gender, age, education and area of residence),
behavioural (alcohol and tobacco consumption) and anthropometric
[body mass index (BMI) and abdominal obesity] variables among
15- to 64-year-olds in the Dande-HDSS population.
Methods
A cross-sectional, community-based survey was conducted
from September 2013 to March 2014 in the catchment area of
the Dande-HDSS, located in Dande municipality of Bengo Province,
Angola.
18
A representative gender- and age-stratified random
sample list of 3 515 individuals, aged between 15 and 64 years, was
drawn, as described previously.
19
Of these, we were able to examine
2 484 (70.7%) individuals, 750 (21.3%) were unreachable and 281
(8.0%) refused to participate, thus approaching the predicted non-
participation rate of 30%.
19
Foranalysis,weexcludedparticipantswithmissinganthropometric
values (
n
= 14) and pregnant women (
n
=116) due to the fact that
anthropometric parameters vary during pregnancy. Therefore 2 354
individuals (67.0%) were included in the final analysis.
Information on age, completed years of school education,
alcohol and tobacco consumption, and the previous measurement
of any of the conditions under investigation, were collected through
a structured interview conducted by trained interviewers, following
a previously published protocol for data collection based on the
WHO STEPS manual version 3.0.
11,19
For this analysis, age was categorised into five 10-year age
groups: 15 to 24, 25 to 34, 35 to 44, 45 to 54 and 55 to 64
years old. Education was categorised according to the number of
completed years of schooling: none, one to four years, five to nine
years, and 10 years or more. Area of residence was classified as
rural or urban, as previously described.
18
Alcohol consumption was
defined as none if participants reported no alcohol consumption;
occasional if participants reported drinking alcohol two or less days
per week; and frequent if drinking any alcohol three or more days
per week. Current tobacco smokers were defined as participants
who reported smoking at least one cigarette per day.
Previous measurements of blood pressure, and glucose or
cholesterol levels in the last year were requested fromall participants.
In the case of a positive answer, participants were questioned
about their awareness of a previous diagnosis of hypertension,
diabetes or hypercholesterolaemia made by a healthcare worker.
Any individual was considered under treatment if he/she indicated
the use of a specific medication; a participant was considered
controlled if they had a current normal value.
Certified health professionals conducted all anthropometric and
clinical measurements, as described previously.
19
Anthropometric measurements were performed with individuals
wearing light clothing and no footwear, and an overnight fast was
requested of all participants.
Body mass and height were measured using a digital scale SECA
803 (SECA United Kingdom, Birmingham, UK) and a portable
stadiometer SECA 213 (SECA United Kingdom, Birmingham, UK).
BMI was defined as the body mass (kg) divided by the square of
the body height (m
2
), and further categorised according to WHO
as underweight (< 18.5 kg/m
2
), normal (18.5 to 24.99 kg/m
2
),
overweight (25.0 to 29.99 kg/m
2
) and obese (≥ 30 kg/m
2
).
20
Waist and hip circumferences were measured using
circumference tape SECA 203 (SECA United Kingdom, Birmingham,
UK). The waist-to-hip ratio was calculated as the circumference
of the waist (cm) to that of the hips (cm), and abdominal obesity
was defined as waist-to-hip ratio ≥ 0.9 for men and ≥ 0.85 for
women.
21
Blood pressure was measured on the right arm with the
automatic sphygmomanometer OMRON M6 Comfort (OMRON
Healthcare Europe BV, Hoofddorp, The Netherlands), with the
individual seated, and using an appropriate cuff size. Three
readings were done at three-minute intervals. The mean value
of the last two measurements was used to determine the blood
pressure. Hypertension was defined as systolic blood pressure of
≥ 140 mmHg and/or diastolic blood pressure ≥ 90 mmHg and/ or
use of antihypertensive drugs during the previous two weeks.
22
Blood sugar was measured using a blood glucose meter
ACCU-CHEK Aviva (Roche Diagnostic, Indianapolis, IN, USA) with
ACCU-CHEK Aviva glucose reactive strips (Roche Diagnostic,
Indianapolis, IN, USA). The definition of diabetes followed WHO
diagnostic criteria of 126 mg/dl (6.9 mmol/l) glucose in a fasting
blood sample,
23
and/or use of antidiabetic drugs during the
previous two weeks.
Total cholesterol in the blood was measured using a point-of- care
device ACCUTREND Plus (Roche Diagnostic, Indianapolis, IN, USA)
with ACCUTREND cholesterol reactive strips (Roche Diagnostic,
Indianapolis, IN, USA). Hypercholesterolaemia was defined
according to WHO diagnostic criteria for STEPS, with cholesterol ≥
240 mg/dl (6.2 mmol/l) in a fasting blood sample,
2,11
and/or use of
anticholesterol drugs during the previous two weeks.
All procedures performed in this study were in accordance with
the standards of the ethics committee of the Angolan Ministry
of Health and with the 1964 Helsinki declaration and its later
amendments. Written informed consent was obtained from all
individual participants included in the study (in the case of those
under 18 years old, from their parent or legal guardian).
A copy of the signed consent form, as well as instructions
regarding the fasting period and contact information, were
delivered to each participant.
Statistical analysis
Data were double entered into a PostgreSQL
®
database and SPSS
®
version 22 (IBM Corp, Armonk, NY, USA) was used for statistical
analysis. Post-stratification survey weights were calculated
using the known gender and categorical age distribution of the
Dande-HDSS population,
17
and these were used in all further
calculations. Descriptive data are reported as absolute frequencies
and percentages or means and standard deviations (SD), as
appropriate.
To facilitate comparisons with other studies, the prevalence of the
three conditions under study was determined for three age groups:
15 to 64, 18 to 64 and 25 to 64 years. Logistic regression models
were fitted to the categorical variable of age because of its
known effect on hypertension, diabetes and hypercholesterolaemia.
Gender-specific adjusted odds ratios (OR) were estimated for each
variable (age, residence, education, BMI, abdominal obesity, tobacco
and alcohol consumption) related to the conditions studied. A 95%