May Measurement Month 2021: an analysis of blood pressure screening results from South Africa.

Elevated blood pressure (BP) is a growing burden worldwide, leading to over 10 million deaths each year. In Sub-Saharan Africa, hypertension prevalence is higher and cardiovascular events occur at a younger age than in Europe or America. May Measurement Month (MMM) is a global campaign initiated by the International Society of Hypertension (ISH) aimed at raising awareness of high BP. In South Africa, the MMM campaign in 2017, 2018, and 2019 revealed that approximately one-third of adults had hypertension, only half of hypertensives were receiving antihypertensive therapy, and only a third of those with hypertension had controlled BP. These data highlight the need for continued BP screening and awareness campaigns in South Africa. From May to November 2021, a cross-sectional survey of volunteers aged ≥18 years was performed. Blood pressure measurements, definition of hypertension, and statistical analyses followed the MMM protocol. The screening sites targeted the general population mainly on university campuses and pharmacies in preference to hospitals and clinics, aiming to raise awareness and allow access to screening in those less likely to be aware of their BP status. Of the 2294 individuals (age 37.3 ± 16.9 years) screened, 30.8% had hypertension. Of those with hypertension, only 48.6% were aware and 43.5% were receiving treatment for hypertension. A large proportion (50.4%) of individuals receiving antihypertensive medication had uncontrolled BP (≥140/90 mmHg). In conclusion, the high prevalence of hypertension, despite the young adult age, and the high proportions of individuals unaware of their hypertension and with uncontrolled BP underscore the necessity for hypertension awareness campaigns and more rigorous management of hypertension.

Low grade inflammation and ECG left ventricular hypertrophy in urban African males: The SABPA study.

BACKGROUND: Hypertension and vascular hyperresponsiveness have been associated with structural wall abnormalities in black Africans. Whether low grade inflammation would have an additive effect is uncertain. Therefore, a novel investigation aimed to assess whether inflammation and pressure overload would have an additive association with ECG left ventricular hypertrophy (LVH). METHODS: We included 75 African and 87 Caucasian males. Ambulatory blood pressure monitoring was done in the working week. A resting 12-lead ECG recording was used for the determination of LVH with the Cornell product formula. Fasting blood samples were obtained for high sensitivity C-reactive protein (hs-CRP) analyses after a controlled overnight stay. Men were stratified into low (≤3 mg/L) and high (>3 mg/L) hs-CRP groups. RESULTS: African men revealed higher ambulatory blood pressure levels compared to Caucasian men independent of hs-CRP levels after adjustment for age, physical activity, cotinine, log γ-GT and body surface area. In forward stepwise linear regression analyses, SBP was positively associated with ECG LVH in all Africans. Considering low grade inflammatory status (>3 mg/L hs-CRP), SBP [Adj R(2)=0.49 (ß=0.99, 0.45, 1.44), p≤0.01] and pulse pressure [Adj R(2)=0.61 (ß=0.0.34, 0.88), p≤0.01] respectively, predicted ECG LVH in African but not in Caucasian men. CONCLUSIONS: Hyperdynamic blood pressure and inflammation acted in tandem as possible promoting factors to structural wall abnormalities in African men.

Nocturnal blood pressure, 3-methoxy-4-hydroxyphenylglycol and carotid intima-media thickness: The SABPA study.

BACKGROUND: Research demonstrated a significant relationship between elevated nocturnal blood pressure and sympathetic hyperactivity. The study aimed to investigate possible associations between norepinephrine metabolite, 3-methoxy-4-hydroxyphenylglycol (MHPG), nocturnal BP and carotid intima-media thickness (CIMT) in urban African and Caucasian men. METHODS: The study included 82 African and 100 Caucasian male teachers, aged 33-56 years, recruited in the North-West Province, South Africa. Ambulatory BP and fasting saliva and blood samples were collected. B-mode ultrasound images were obtained to determine CIMT. RESULTS: Despite higher usage of anti-hypertensive medication usage (p=0.039), a large number of the African men were nocturnal hypertensives (75, 61%). The nocturnal systolic blood pressure (SBP) (p<0.001), diastolic blood pressure (DBP) (p<0.001) and heart rate (p<0.001) of the African men were higher. After stratifying groups into only nocturnal hypertensives the trend was the same (SBP p<0.001; DBP p<0.001; heart rate p=0.058). In the African and Caucasian men, CIMT was linearly predicted by SBP (ß=0.33, p<0.001) and DBP (ß=0.24, p=0.016) respectively, but not MHPG. CONCLUSION: No associations were firstly demonstrated between MHPG as sympathetic activity marker and CIMT or secondly, between MHPG and nocturnal blood pressure. Novel findings of elevated nocturnal BP evidently seem to promote structural vascular disease in urban African and Caucasian men.

High prevalence but lack of awareness of hypertension in South Africa, particularly among men and young adults.

Cardiovascular disease (CVD) is a leading cause of death in South Africa (SA) and high blood pressure (BP) is the primary risk factor. However, hypertension prevalence is high, BP control is poor and CV events occur at a younger age than in Europe or America. Increasing screening, raising awareness and improving management of hypertension are critical to prevent CVD in SA. May Measurement Month (MMM) is a global initiative of the International Society of Hypertension aimed at raising awareness of high BP. As part of the MMM campaign, in SA (2017, 2018, 2019 and 2021), BP measurements and a cross-sectional survey of volunteers aged ≥ 18years were performed. Of 11,320 individuals (age 36.6 ± 16.8years) screened, 29.7% had hypertension (systolic BP/diastolic BP ≥ 140/90 mmHg or antihypertensive medication use) and the prevalence was higher (p < 0.0001) in men (35.6%) than in women (26.3%). Of those with hypertension, only 54.3% were aware and 46.8% were receiving antihypertensive medication, and 53.7% of these had controlled BP. In men with hypertension, awareness (45.2%, treatment (38.2%) and controlled BP on antihypertensive medication (45.2%) were lower (p < 0.0001) than in women (awareness: 60.8%; treatment: 53.5%; controlled BP: 58.3%). In young participants (age < 40years), 15.6% had hypertension, 18.6% of these were on treatment but 76.0% were not aware, and only 57.7% had controlled BP. The high prevalence of hypertension, but low levels of awareness, treatment, and BP control in SA, especially in young adults and men, highlight the need for systematic BP screening programmes and improvements in education and management of hypertension.

Characterization of the Renin-Angiotensin-Aldosterone System in Young Healthy Black Adults: The African Prospective Study on the Early Detection and Identification of Hypertension and Cardiovascular Disease (African-PREDICT Study).

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Assessing tobacco use in an African population: Serum and urine cotinine cut-offs from South Africa.

BACKGROUND: Cotinine, a nicotine metabolite, is used to measure tobacco use and exposure, but recommended cut-offs to differentiate tobacco users from those exposed through the environment range from 3 to 58 ng/ml in serum, and 2.5 to 550 ng/ml in urine. Cut-offs may differ by ethnicity, sex and age. As data from adults in Africa are scarce, our aim was to evaluate cut-offs for serum and urine cotinine that best predict self-reported tobacco use in South African adults. METHODS: Two datasets were explored: African-PREDICT (n = 941 black and white healthy young adults, 20-30 years, serum cotinine); and WHO SAGE Wave 2 (n = 604 adults, 18-102 years, urine cotinine). Population specific cut-offs (ROC analyses) were compared with published cut-offs and self-reported tobacco use. RESULTS: Overall, 19% (293 of 1545) reported current tobacco use. The following cotinine cut-offs showed the highest sensitivity and specificity: serum ≥15 ng/ml in black and white men, and white women; serum ≥10 ng/ml in black women; urine ≥300 ng/ml for black, mixed ancestry, and older adults (50-plus years); urine ≥500 ng/ml for younger adults (18-49 years). Specificity was lower for urine than for serum cotinine. CONCLUSION: Our study suggests that a serum cotinine level of ≥15 ng/ml and a urine cotinine level of ≥300 ng/ml best distinguish current tobacco users from non-users generally in the South African adult population.

The African Prospective study on the Early Detection and Identification of Cardiovascular disease and Hypertension (African-PREDICT): Design, recruitment and initial examination.

BACKGROUND: Globally hypertension is stabilising, but in sub-Saharan Africa the incidence of hypertension remains on an increase. Although this might be attributed to poor healthcare and ineffective antihypertensive treatment, there is a limited understanding of population and individual-specific cardiovascular pathophysiology - necessary for effective prevention and treatment strategies in Africa. As there is a lack of longitudinal studies tracking the early pathophysiological development of hypertension in black populations, the African-PREDICT study was initiated. The purpose of this paper is to describe the detailed methodology and baseline cohort profile of the study. METHODS AND RESULTS: From 2013 to 2017, the study included 1202 black ( N = 606) and white ( N = 596) men and women (aged 20-30 years) from South Africa - screened to be healthy and clinic normotensive. At baseline, and each 5-year follow-up examination, detailed measures of health behaviours, cardiovascular profile and organ damage are taken. Also, comprehensive biological sampling for the 'omics' and biomarkers is performed. Overall, the baseline black and white cohort presented with similar ages, clinic and 24-hour blood pressures, but black adults had lower socioeconomic status and higher central systolic blood pressure than white individuals. CONCLUSIONS: The prospective African-PREDICT study in young black and white adults will contribute to a clear understanding of early cardiovascular disease development.