Cardiovascular Journal of Africa: Vol 31 No 1 (January/February 2020)

CARDIOVASCULAR JOURNAL OF AFRICA • Volume 31, No 1, January/February 2020

AFRICA

done allowing for hypertension prevalence to vary by age and

BMI at the geographic (district) level. This analysis was used

to graphically identify units with relatively steeper slopes by

age and BMI.

All analyses were performed using Stata version 15. For design-

based prevalence estimate, the ‘svy: tab’ command for two-way

tabulation was used, while the mixed-effect logit (melogit)

command was used for multilevel analysis.

Results

Design-based (unadjusted) prevalence of hypertension

: the

univariate (weighted) analysis (Table 2) shows a decreased trend

in hypertension prevalence, except for a slight increase in the

2012 period. On a period-by-period basis, the prevalence of

hypertension in females was higher than that of males. Age,

BMI status and educational level had the highest differentials,

with those relatively older (40+ years) having a prevalence that

was about four times that of the younger adults (

40 years), and

those whose BMI was 25 kg/m

or above (overweight or obese)

having a prevalence almost double that of those with a BMI less

than 25 kg/m

(normal weight).

Subjects who had primary-level education or no education had

a significantly higher prevalence compared to those with relatively

higher educational levels, and those who were unemployed had

lower prevalence compared with the employed and economically

Table 2. Percentage (95% CI) of hypertension prevalence in South Africa by covariate and period

Characteristic

2008

2010/11

2012

2014/15

2017

Average (all)

Gender

Female

33.7 (31.7–35.7)

31.9 (30.2–33.7)

33.5 (31.8–35.2)

29.4 (27.8–31.0)

28.5 (27.1–29.9)

31.2 (30.1–32.4)

Male

28.7 (26.5–30.9)

27.8 (25.5–30.2)

30.4 (28.0–32.9)

26.8 (24.7–28.9)

27.3 (25.6–29.1)

28.1 (26.5–29.8)

Age group

≤

40 years

16.4 (14.8–18.1)

16.0 (14.6–17.5)

17.3 (15.8–18.9)

13.8 (12.4–15.4)

13.9 (12.8–15.0)

15.3 (14.4–16.3)

> 40 years

58.0 (55.5–60.4)

55.0 (52.6–57.3)

57.2 (54.8–59.5)

53.0 (51.0–55.0)

52.7 (50.6–54.7)

55.0 (53.5–56.4)

Race

African

29.2 (27.5–30.9)

28.2 (26.8–29.6)

30.0 (28.3–31.7)

25.6 (24.4–26.9)

25.4 (24.3–26.6)

27.5 (26.5–28.5)

Mixed race

41.7 (37.4–46.1)

41.1 (35.1–47.3)

40.2 (34.7–45.9)

39.3 (35.8–42.8)

38.3 (34.3–42.5)

39.9 (36.2–43.7)

Asian/Caucasian

40.6 (35.8–45.7)

35.7 (29.0–43.1)

40.1 (35.1–45.4)

36.5 (29.5–44.2)

39.9 (35.7–44.3)

38.6 (34.7–42.6)

Residency

Urban

33.4 (31.2–35.6)

32.6 (30.6–34.7)

33.0 (30.8–35.2)

29.5 (27.5–31.6)

29.3 (27.8–30.9)

31.3 (29.9–32.7)

Traditional/farms

28.8 (26.8–30.9)

26.2 (24.6–27.9)

30.6 (28.6–32.7)

25.9 (24.5–27.3)

25.2 (23.8–26.7)

27.3 (26.2–28.5)

Education level

≤

Primary

46.1 (43.4–48.8)

45.3 (43.1–47.6)

48.9 (46.3–51.4)

48.1 (45.9–50.3)

47.9 (45.5–50.4)

47.2 (45.4–49.0)

High school

24.7 (22.6–26.8)

23.4 (21.6–25.3)

25.6 (23.6–27.8)

21.5 (19.7–23.4)

21.5 (20.1–23.0)

23.2 (21.8–24.7)

Certificate/diploma/bachelors’+ 28.1 (24.6–31.9)

28.3 (24.1–32.9)

31.0 (27.8–34.5)

26.8 (24.0–29.9)

29.4 (27.1–31.8)

28.7 (26.8–30.7)

Income tertile

Low

29.1 (27.3–31.0)

27.3 (25.7–28.9)

28.7 (26.5–30.9)

24.4 (22.5–26.4)

23.5 (20.6–26.7)

27.3 (26.1–28.5)

Medium

33.3 (30.7–36.0)

31.8 (29.4–34.3)

32.4 (30.4–34.4)

27.7 (25.9–29.6)

26.1 (24.6–27.6)

29.9 (28.6–31.2)

High

34.3 (31.3–37.4)

32.0 (29.1–35.0)

34.4 (31.8–37.1)

29.8 (27.7–32.0)

29.8 (28.3–31.3)

31.4 (29.9–32.9)

Employment status

Employed

32.8 (30.6–35.1)

31.4 (28.8–34.2)

32.9 (30.7–35.2)

28.6 (26.6–30.7)

27.8 (26.2–29.4)

30.3 (29.0–31.8)

Unemployed

24.4 (21.8–27.1)

23.1 (19.9–26.7)

23.4 (20.6–26.5)

19.8 (16.8–23.1)

19.9 (17.4–22.7)

22.2 (20.6–23.9)

Economically inactive

33.8 (31.3–36.3)

31.2 (29.5–33.0)

34.6 (32.5–36.7)

30.3 (28.5–32.1)

30.4 (28.8–32.1)

31.9 (30.5–33.3)

Medical aid

Yes

35.7 (31.3–40.4)

31.7 (26.7–37.2)

36.8 (32.7–41.0)

33.2 (28.9–37.9)

33.3 (30.0–36.7)

29.0 (28.0–30.1)

30.8 (29.2–32.5)

29.7 (28.3–31.2)

31.3 (29.7–32.9)

27.2 (25.9–28.6)

26.9 (25.7–28.2)

34.1 (31.4–36.9)

Body mass index

Below overweight

21.5 (19.7–23.3)

20.1 (18.5–21.7)

21.2 (19.4–23.1)

16.8 (15.4–18.2)

17.1 (15.8–18.5)

19.1 (18.1–20.2)

Overweight/obese

40.7 (38.5–42.9)

38.7 (36.7–40.8)

41.9 (39.7–44.0)

38.6 (36.6–40.7)

38.2 (36.6–39.7)

39.5 (38.2–40.9)

Exercise

Never exercise

34.2 (32.5–36.0)

32.2 (30.5–33.9)

34.0 (32.3–35.8)

31.1 (29.5–32.6)

30.7 (29.4–32.1)

32.3 (31.3–33.4)

Some exercise

26.7 (24.0–29.5)

25.4 (22.7–28.4)

27.8 (24.9–30.8)

23.1 (20.8–25.6)

22.8 (21.1–24.5)

24.9 (23.2–26.7)

Alcohol use

Yes

34.1 (31.5–36.9)

30.5 (27.4–33.8)

33.3 (30.7–36.0)

29.8 (27.4–32.3)

30.3 (27.7–33.0)

29.5 (28.3–30.8)

30.6 (28.8–32.4)

29.9 (28.3–31.5)

31.6 (29.9–33.3)

27.3 (25.9–28.9)

28.4 (27.0–29.8)

31.4 (29.7–33.2)

Unknown

–

23.5 (21.2–26.0)

Smoking status

Never smoked

30.6 (29.0–32.3)

29.2 (27.7–30.8)

31.0 (29.3–32.7)

26.7 (25.3–28.2)

26.9 (25.7–28.1)

28.7 (27.7–29.8)

Ever smoked

33.9 (31.2–36.7)

33.2 (29.8–36.9)

35.9 (32.2–39.8)

32.3 (29.2–35.6)

30.9 (28.6–33.4)

33.1 (31.0–35.3)

Season of BP measurement

Summer

29.3 (26.8–31.8)

24.4 (21.3–27.8)

25.3 (20.4–30.9)

25.4 (24.0–26.9)

24.7 (23.0–26.5)

26.1 (25.0–27.3)

Winter

35.8 (32.8–39.0)

31.9 (29.8–34.1)

32.9 (30.7–35.2)

32.2 (27.9–36.8)

31.3 (29.2–33.4)

32.5 (31.2–33.9)

Autumn/spring

32.2 (29.7–34.9)

28.8 (26.6–31.2)

31.6 (29.4–33.9)

30.5 (27.9–33.3)

29.0 (27.1–30.9)

30.4 (29.0–31.8)

All

31.5 (29.9–33.1)

30.0 (28.6–31.5)

32.1 (30.5–33.8)

28.2 (26.8–29.6)

27.9 (26.7–29.1)

29.8 (28.7–30.9)