In summary, the data show that amongst an opportunistic sample of adults in South Africa, the prevalence of hypertension is high (~30%) despite the low mean age (<40 years). However, the proportions of individuals with hypertension receiving treatment for hypertension and aware of their hypertension were low (<50%). Consequently, the proportion of participants with hypertension who were treated and who had controlled BP was also low (~50%). More men than women were hypertensive, and the proportions of hypertensives receiving treatment for hypertension, aware of their hypertension and with controlled BP were lower in men than in women. Ethnicity had little impact on the proportion with hypertension, but treatment, awareness and the proportion treated with controlled BP were the lowest amongst those of mixed ancestry. Hypertension prevalence was the highest in the Western Cape, but the proportions of individuals with hypertension receiving treatment for hypertension, aware of their hypertension and the proportion treated with controlled BP were also the highest in this province. The proportions of individuals with hypertension receiving treatment for hypertension and aware of their hypertension were the lowest in the North West Province.

The prevalence of hypertension in an opportunistic sample of adults in South Africa is similar to that reported globally (34%); but the proportions of hypertensives receiving antihypertensive medication or who were aware of their diagnosis of hypertension were lower than those reported globally (medication: 54.7%; aware: 58.7%) [11]. Nevertheless, the proportion of South African participants with hypertension who were receiving antihypertensive treatment and had controlled BP was similar to that reported globally (57.8%) [11]. The proportions of South Africans with hypertension, aware of their hypertension and having controlled BP on antihypertensive medication were similar to the proportions reported in sub-Saharan Africa (hypertension: 27.9%; aware: 42.7%; controlled: 49.3%), except for the proportion of South Africans receiving treatment for their hypertension which was greater than in sub-Saharan Africa (34.5%) [11]. Although the proportion with hypertension in an opportunistic sample of adults in South Africa was lower than in Europe (43.6%), the mean age in Europe was at least a decade older (50.5 years). Indeed, when age- and sex-standardised proportions were compared, the proportion with hypertension in sub-Saharan Africa did not differ significantly from that in Europe (31.2% and 36.2%, respectively) [11]. However, the proportions of participants with hypertension and receiving treatment for their hypertension and aware of their condition in South Africa were substantially lower than in Europe (64.4 and 71.5%, respectively). The proportion of individuals with hypertension receiving treatment for hypertension is reported to be influenced by country income, with 62% of individuals with hypertension receiving antihypertensive medication in high-income countries compared to only 51.5% in low to middle-income countries [11]. Nevertheless, the proportion of South Africans with hypertension and controlled BP was similar to that in Europe (47.9%) [11].

With regards to age, it is well known that the prevalence of hypertension increases with advancing age. However, it is worth noting that although the current study in an opportunistic sample, shows that 15.6% of young (<40 years of age) adults in South Africa have hypertension, awareness of hypertension among these young participants with hypertension is remarkably low (24.0%). A study of young adults in the United States similarly reported low levels of hypertension awareness in the young (32% in women with hypertension and 25% in men with hypertension men), despite 12% of young women and 27% of young men having hypertension [12]. Although in the National Health and Nutrition Examination Survey (NHANES), the awareness of hypertension was greater than in an opportunistic sample of South Africans, young (<40 years of age) adults tended to have particularly low hypertension awareness (~45%); whereas older (>40 years of age) participants tended to be more aware of their hypertensive status (>70%) [13]. These age discrepancies in awareness have been attributed to younger adults tending to be healthier; being less likely to see doctors on a regular basis; thus, decreasing the likelihood that they will have accurate and up-to-date knowledge of their BP status. In the current study, treatment of hypertension was also low in the young adults (18.6%). These data in an opportunistic sample support similar reports of ~20% of younger adults with hypertension receiving treatment as compared to >55% of older adults with hypertension in a population sample [13]. Therefore, lack of treatment of hypertension and lack of awareness of hypertension seem to be particularly problematic amongst young adults. In order to prevent the long-term sequelae of hypertension it would be pertinent to encourage BP screening and improve awareness of hypertension particularly in young adults.

With respect to gender, the greater prevalence of hypertension in male compared to female South Africans is similar to global data, where up until 80 years of age, both systolic and diastolic BP were higher in males when compared to females [11]. The higher prevalence of hypertension and greater BP values in men compared to women especially prior to menopause are well documented [6, 7, 14, 15]. Mechanisms for the sex differences in hypertension have been linked to various hormonal systems. Oestrogen via the activation of nitric oxide is associated with a lower BP in women [16]. In addition, data obtained in animal models of hypertension suggests that the greater anti-inflammatory immune profile reported in hypertensive females, may act as a compensatory mechanism to limit increases in BP [17]. In comparison, males exhibit a more pro-inflammatory immune profile. Although, the mechanisms underlying these changes in immune cells in hypertensive males and females are not well understood; a possible mediator is the angiotensin type 2 receptor, which promotes an anti-inflammatory immune profile and has a greater activity in females [18].

In addition to sex differences in the prevalence of hypertension, the proportions of hypertensives receiving treatment for their hypertension or aware of their hypertensive status also differed according to sex. In this regard, the current study in an opportunistic sample of adults, showed that treatment and awareness were lower in men compared to women. Discrepancies of treatment and awareness of hypertension between genders have previously been reported. Indeed, a study of young adults in the United States similarly reported lower levels of hypertension awareness in men compared to women, especially amongst those younger than 40 years of age (32% in young hypertensive women compared to 25% in young hypertensive men) [12]. Reports on sex differences in hypertension awareness have produced consistent results, with women having higher levels of hypertension awareness than in men [13, 19, 20]. With regards to BP control in an opportunistic sample of adults, we found that a higher proportion of women had controlled BP compared to men. Similarly, in NHANES from 1999–2014, young adult males were found to have poorer control of hypertension compared to all other age cohorts and age-matched females [21]. The incongruity in BP control according to sex in NHANES, was hypothesised to be due to more frequent healthcare visits by young adult women versus age-matched men [21]. Indeed, globally in MMM, the proportion of individuals reporting never having had their BP measured previously, was higher in men (35.9%) than in women (28.9%) [11]. These data suggest that particular attention should be made to increase screening, awareness and treatment of hypertension in men.

The lack of impact of ethnicity on the prevalence of hypertension in the current study (an opportunistic sample of adults), differs from data in the SANHANES 2011–2012, where hypertension was more prevalent in Indian/Asian (44.9%), Coloured (40.5%), and White (40.4%) participants than in African participants (32.9%), despite similar overall prevalence of hypertension (35.3%) [6]. However, Reddy et al. [6] reported that amongst African participants there was a lower prevalence of hypertension in rural informal compared to urban formal settings. Our data of similar prevalence of hypertension amongst African participants compared to other ethnic groups may be a consequence of screening individuals primarily from urban formal settings. In the current study, the highest prevalence of hypertension was amongst those of mixed ancestry, which agrees with data from the 2016 South African DHS where hypertension was reported to be higher in those of mixed ancestry [7].

In the current study (an opportunistic sample of adults), the highest prevalence of hypertension was observed in the Western Cape, whereas the lowest prevalence was in the North West Province. In the 2016 South African DHS, the highest prevalence was found in KwaZulu Natal with the lowest prevalence in Limpopo [7]. In comparison, in 2012, the SANHANES found that the prevalence of hypertension was the highest in the North West Province and the lowest in Limpopo [6]. The current study also showed provincial differences in the prevalence of hypertension awareness, treatment and BP control. However, neither SANHANES [6] nor the South African DHS [7] reported on hypertension awareness, treatment and BP control.

In line with the United Nations Declaration on the Prevention and Control of Non-Communicable Diseases, in 2022 South Africa developed a National Strategic Plan (NSP) in which they proposed a 90-60-50 cascade for hypertension as the first step to improving early detection and treatment of non-communicable disease [22]. The plan is that by 2030, 90% of all people over 18 years of age will know whether or not they have raised BP, 60% of people with raised BP will receive intervention, and 50% of people receiving interventions will have controlled BP [22]. The data from the current study shows that we are far from realising the South African NSP goal with regard to awareness of hypertension. However, we are closer to the goals of proportions being treated and at least 50% of those treated do have controlled BP. Hence, South Africa needs to increase screening considerably to improve awareness of hypertension and once diagnosed management needs to be instituted.