The SA Journal Diabetes & Vascular Disease Vol 16 No 1 (July 2019)

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SA JOURNAL OF DIABETES & VASCULAR DISEASE RESEARCH ARTICLE
VOLUME 16 NUMBER 1 • JULY 2019 31
Table 1. Descriptive statistics for anthropometric parameters, skinfold
thickness and blood pressure among young Ellisras adults
Variable Men (n = 364) Women (n = 375) p-value
Age, years 25.44 ± 2.60 25.52 ± 2.53 0.636
SBP, mmHg 125.33 ± 12.95 114.32 ± 10.23* 0.000
DBP, mmHg 71.67 ± 10.11 69.43 ± 9.12* 0.002
Biceps skinfold, cm 3.62 ± 2.10 10.70 ± 6.44* 0.000
Triceps skinfold, cm 6.46 ± 4.30 12.41 ± 7.20* 0.000
Subscapular skinfold, cm 8.71 ± 3.28 12.59 ± 6.80* 0.000
Supraspinale skinfold, cm 5.11 ± 3.57 12.34 ± 7.19* 0.000
Waist-to-height ratio 0.434 ± 0.082 0.509 ± 0.122* 0.000
Waist circumference, cm 74.74 ± 9.56* 82.49 ± 14.73* 0.000
Mean ± SD; *p < 0.05.
SBP, systolic blood pressure; DBP, diastolic blood pressure.
30 years (365 females and 377 males), who were part of the ELS,
participated in this survey.
The ethics committee of the University of the North, now known
as the University of Limpopo, granted approval prior to the survey.
Participants read and signed informed consent forms. All subjects
went through a series of anthropometric measurements based on
the standard procedures recommended by the International Society
for the Advancement of Kinanthropometry (ISAK).17 Skinfold
(triceps, biceps, subscapular and supraspinale) and height were
measured using both the Martin anthropometer and Slim Guide
skinfold calliper. Height was rounded off to the nearest 0.1 cm
and skinfolds were measured three times, where the values were
rounded off to the nearest 0.1 mm. A flexible steel tape was used
to measure WC in centimetres as participants assumed a standing
position. WC was measured sideways from midway between the
lowest portion of the rib cage and iliac crest and anteriorly, midway
between the xiphoid process of the sternum and the umbilicus.
Measurements for both systolic (SBP) and diastolic blood
pressure (DBP) were taken at least three times with the electronic
Micronta monitoring kit at an interval of five minutes, after the
participants had been sitting for at least 15 minutes in a well-
ventilated room.18,19 The device contained an infrasonic transducer
that keeps records of BP and pulse rate on the display screen. The
device has been used for research and clinical purposes.20 Readings
taken with a conventional mercury sphygmomanometer and an
automated device showed a high correlation (r = 0.93), based on a
pilot study conducted before the actual survey.
Readings for intra- and inter-tester technical errors of
measurement (% TEM) for height, skinfolds and WC ranged from
0.04 to 4.16 cm (0.2–5.01%), 0.2 to 6 mm (0.4–6.8%) and 0 to
3.4 cm (0–4%), respectively.12
Statistical analysis
Descriptive statistics for WC, WHR and skinfold thickness were
computed. Independent t-tests were calculated to examine whether
there were any significant gender differences in the participants’
anthropometric and haemodynamic measurements. Hypertension
was defined as SBP ≥ 140 mmHg or DBP ≥ 90 mmHg, according
to WHO.21 Central obesity was assessed based on WC and WHR
as follows: WC in men ≥ 102 cm and in women ≥ 88 cm, and
WHR ≥ 0.5 cm in both men and women.22 The sum of four skinfold
measurements (triceps, biceps, subscapular and supraspinale),
categorised as above the 85th percentile, was used to determine
general obesity, where young adults were characterised as normal
or excessively fat.23
The association between BP, WHR, WC and skinfolds, adjusted
for age and gender, was assessed using a linear regression model.
The risk of developing hypertension among young Ellisras adults
who were obese or overweight was assessed with multinomial
logistic regression analysis. Data were analysed using the Statistical
Package for the Social Sciences (SPSS) (version 23), with the level of
significance set at p < 0.05.
Results
Table 1 presents descriptive statistics for anthropometric parameters,
skinfolds and BP among young Ellisras adults aged 22 to 30 years.
Women showed significantly (p < 0.05) higher mean average WC
(82.49 ± 14.73 cm) than men (74.74 ± 9.56 cm) (p < 0.000). Men
showed a significantly higher mean SBP (125.33 ± 2.60 mmHg)
than women (114.32 ± 10.23 mmHg).
Presented in Table 2 are the summary data on the prevalence
of hypertension, overweight and central obesity among the
participants as evaluated using anthropometric parameters (WC,
WHR and skinfold thickness). There was a higher significant (p <
0.000) prevalence of central obesity in women (69.6%) than in
men (1.4%), while the prevalence of overweight was higher in men
(15.4%) than women (15.1%), although not significant. High SBP
was significantly (p < 0.05) more prevalent in men (14.0%) than in
women (1.9%).
Table 3 indicates the Pearson correlation coefficients
between anthropometric parameters, skinfold thickness and
BP measurements. There were significant ( p < 0.05) correlations
between triceps (r = 0.022), biceps (r = 0.021) and subscapular
(r = 0.053) skinfolds and SBP in women, while DBP in women
was significantly ( p < 0.05) associated with triceps (r = 0.046),
biceps (r = 0.007) and subscapular ( r = 0.013) skinfolds. In men,
SBP significantly (p < 0.05) correlated with triceps (r = 0.012) and
biceps (r = 0.015) skinfolds, while DBP was substantially (p < 0.05)
correlated with biceps (r = 0.017) and subscapular ( r = 0.054)
skinfolds.
Table 2. Prevalence of central obesity, overweight and hypertension
among young rural Ellisras adults
Variable Men, n (%) Women, n (%) p-value*
High WC 5 (1.4) 134 (35.4) 0.000
High WHR 110 (30.2) 263 (69.6) 0.000
Overweight 56 (15.4) 57 (15.1) 0.142
High SBP 51 (14.0) 7 (1.9) 0.013
High DBP 11 (3.0) 9 (2.4) 0.312
Hypertension 8 (2.2) 5 (1.3) 0.003WC, waist circumference; WHR, waist-to-
hip ratio; SBP, systolic blood pressure; DBP, diastolic blood pressure.
Table 3. Pearson’s correlation coefficient between blood pressure and
anthropometric parameters (skinfold thickness, WC and WHR)
Variable Triceps Biceps Subscapular Supraspinale WHR Waist
Women
SBP 0.022** 0.021** 0.053** 0.140 0.175 0.237
DBP 0.046** 0.007** 0.013** 0.093 0.136 0.684
Men
SBP 0.012** 0.015** 0.120 0.016 0.231 0.303
DBP 0.059 0.017** 0.054** 0.068 0.171 0.211
**Correlation is significant at the 0.05 level (two-tailed).
SBP, systolic blood pressure; DBP, diastolic blood pressure.