CARDIOVASCULAR JOURNAL OF AFRICA • Volume 34, No 3, July/August 2023 AFRICA 157 Prevalence and associated risk factors for elevated blood pressure in young adults in South Africa Sanushka Naidoo, June Fabian, Shane A Norris Abstract Background: Sub-Saharan Africa has been shown to have a high prevalence of hypertension (58% in rural black South Africans) with an accelerated course ending in end-stage renal disease. We sought to determine whether the prevalence of elevated blood pressure (EBP) in early adulthood was associated with any risk factors and/or renal target-organ damage in young adulthood, which could prevent development of these cardiorenal sequelae. Methods: Data including risk factors for hypertension and markers of kidney damage were collected from young adults (n = 933; age 28 years; 52% female) participating in the Birth to Twenty Plus (BT20) cohort in Soweto, South Africa. Blood pressure was measured on one occasion. Results: Fifty-four per cent of the study sample had EBP with more men affected (62%) than women (47%) (p < 0.001). Body mass index (BMI), hyperuricaemia and albuminuria had significant associations with EBP in men. In women, BMI, hyperuricaemia and a self-reported history of gestational hypertension had significant associations. Conclusion: Our findings suggest that the pathophysiology of EBP in young adults differs between the genders and highlights a number of modifiable factors in its development. Keywords: hypertension, young adults, risk factors, target-organ damage Submitted 3/2/22, accepted 2/7/22 Published online 17/8/22 Cardiovasc J Afr 2023; 34: 157–163 www.cvja.co.za DOI: 10.5830/CVJA-2022-036 Chronic non-communicable diseases (NCD) are responsible for 71% of deaths worldwide and four out of five of these deaths occur in low- and middle-income (LMIC) countries. Of these, cardiovascular disease is the most common, with hypertension accounting for 7.1 million deaths annually. Many LMIC countries face combined burdens of infectious and chronic disease, with the latter starting to predominate. For example, in 2018 the leading cause of death in South Africa was tuberculosis, but when grouping chronic diseases together (most frequently diabetes, cardiac and cerebrovascular disease and hypertension), they were responsible for 51% of deaths. Furthermore, chronic diseases tend to emerge earlier in the life course and are responsible for 85% of premature adult NCD deaths in those from LMIC.1 Previously, urban study sites in South Africa have shown that when compared to other population groups, hypertension in black Africans is more severe and associated with greater degrees of target-organ damage (malignant hypertension or kidney injury/kidney failure) for any given level of blood pressure.2 In rural black South Africans, the prevalence of hypertension has been reported as high as 58%, however, studies assessing consequent target-organ damage in the form of kidney injury remain scarce.3 From available data published by the South African Renal Registry (2018), the most common cause of end-stage renal disease in patients on chronic dialysis therapy is hypertension (35%), contradicting high-income countries where the most common cause is diabetes. Similarly, the median age of those receiving chronic dialysis in South Africa was younger (53 years), compared to similar cohorts in the USA, at 63 years.4 We recently reported that the prevalence of elevated blood pressure (EBP) in the Birth to Twenty Plus (BT20) cohort in urban Soweto, South Africa, was 36% at age 22 years and that blood pressure (BP) tracked through childhood and adolescence into early adulthood.5 While our data provide strong evidence of the emergence of EBP early along the life course, we have not investigated whether EBP is associated with target-organ damage, a strong predictor of adverse outcomes. In this study from the BT20 cohort, now aged 28 years, we aimed to determine the prevalence of EBP, characterise associated risk factors and establish whether there was evidence of target-organ damage using surrogate markers for vascular and kidney injury. Methods BT20 is a longitudinal birth cohort following singleton infants (n = 3 273) born to mothers in Soweto, Johannesburg, a predominantly black, urban area, in 1990. Details of recruitment and cohort attrition are described elsewhere.6 For this study, participants who were seen at the 2012 data-collection wave (n = 1 540) were invited to participate at age 28 years. Participants were excluded if they were pregnant at the time of assessment. SAMRC Developmental Pathways for Health Research Unit, School of Clinical Medicine, University of the Witwatersrand, Johannesburg, South Africa Sanushka Naidoo, MD, sanushka.naidoo@wits.ac.za Medical Research Council/Wits University Rural Public Health and Health Transitions Research Unit (Agincourt), School of Public Health, Faculty of Health Sciences; Wits Donald Gordon Medical Centre, School of Clinical Medicine, Faculty of Health Sciences, University of Witwatersrand, Johannesburg, South Africa June Fabian, MD, PhD SAMRC Developmental Pathways for Health Research Unit, School of Clinical Medicine, University of the Witwatersrand, Johannesburg, South Africa; Global Health Research Institute, School of Human Development and Health & NIHR Southampton Biomedical Research Centre, University of Southampton, UK Shane A Norris, PhD
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