Cardiovascular Journal of Africa: Vol 29 No 2 (March/April 2018)

CARDIOVASCULAR JOURNAL OF AFRICA • Volume 29, No 2, March/April 2018

AFRICA

(prevalence of hypertension 45.2% and hypercholesterolaemia

11.1%),

1 464 participants surveyed in the Dande Health and

Demographic Surveillance System (Dande-HDSS) catchment

area (23% prevalence of hypertension),

and a study of 421

subjects from a rural community of Angola (2.8% prevalence

of diabetes).

Building on the work carried out by Pires and colleagues,

and based on the STEPS methodology,

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.

A representative gender- and age-stratified

random sample list of 3 515 individuals, aged between 15 and

64 years, was drawn, as described previously.

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%.

For analysis, we excluded participants with missing

anthropometric values (

14) and pregnant women (

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.

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 from all

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.

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

), and further

categorised according to WHO as underweight (

18.5 kg/m

normal (18.5 to 24.99 kg/m

), overweight (25.0 to 29.99 kg/m

)

and obese (

≥

30 kg/m

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.

Blood pressure was measured on the right arm with the

automatic sphygmomanometerOMRONM6Comfort (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.

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,

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,

and these were

used in all further calculations. Descriptive data are reported