CARDIOVASCULAR JOURNAL OF AFRICA • Vol 23, No 1, February 2012
AFRICA
47
analysed. The prevalence of prehypertension was higher among
men than women (41 vs 34%) (Figs 4, 5). Corresponding with
the result of the meta-regression, the method of blood pressure
measurement had no influence on the prevalence of prehyperten-
sion (Fig. 6). The prevalence rose as the sample size increased.
The prevalence for the subgroup with a sample size over 10
000 individuals was 40%, while for that with a sample size below
5 000, it decreased to 36% (Fig. 7). The studies taking place in
2003 or before had a lower pooled estimate than those after 2003
(35 vs 44%) (Fig. 8). Individuals in non-Asian countries were
more likely to be prehypertensive than their counterparts in Asia
(42 vs 36%) (Fig. 9). In the non-Asian subgroup, the prevalence
of prehypertension among the black African population was 9%
higher than in the non-African population (mainlywhite) (Fig. 10).
Discussion
In the 22 cross-sectional studies included, the prevalence of
prehypertension varied widely. Considering that prehyperten-
sion has developed a more important status in recent years, we
presumed that an overall estimate of prevalence by meta-analysis
would be necessary for further strategies of prevention or treat-
ment of prehypertension.
Our result showed that the overall pooled prevalence of prehy-
pertension among individuals aged 15 years and older was 38%
(95% CI; 32–43%). As a precursor of hypertension, this preva-
lence is relatively high, and effective approaches for prevention
and treatment are needed in order to reduce the development of
hypertension and CVD in this segment of the population.
Gender-related and age-dependent differences in blood pres-
sure levels have been the subject of multiple clinical and epide-
miological studies over the past decades.
33-36
The risk of hyperten-
sion in females increases with age and becomes more prevalent
among women after 59 years of age than among men, probably
due to changes related to the menopause.
37
The mechanisms
Fig. 4. Pooled prevalence of prehypertension in males
according to 22 cross-sectional studies.
Fig. 5. Pooled prevalence of prehypertension in females
according to 22 cross-sectional studies.
Fig. 6. Pooled prevalence grouped by method of BP
measurement.
Fig. 7. Pooled prevalence grouped by sample size.
