ORCID Profile
0000-0002-9762-4017
Current Organisation
University of the Witwatersrand Johannesburg
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Publisher: Elsevier BV
Date: 12-2017
DOI: 10.1016/J.IJCARD.2017.08.070
Abstract: Pulse pressure lification (PPA), i.e. the lification from central arteries to the periphery, is inversely related to arterial stiffness, organ damage and mortality. It is known that arterial stiffness is higher in black than white populations, but it is unclear if this is due to early vascular aging. We therefore investigated whether PPA declines earlier in young normotensive black South Africans, when compared to their white counterparts. We included 875 black and white men and women from the African-PREDICT study (55% black, 41% men), aged 20-30years, with no prior diagnosis of chronic disease, screened for normotensive clinic blood pressure (BP). We determined supine central PP (cPP), and supine brachial systolic- and diastolic BP, from which brachial PP (bPP) was calculated. PPA was defined as the ratio of the litude of the PP between these distal and proximal locations (bPP/cPP). We found the mean PPA to be lower in black compared to white participants (1.43 vs. 1.46 P=0.013). In black adults PPA declined earlier with increasing age (P-trend<0.001), with a weak trend in whites (P=0.069) after adjustment for sex, socio-economic status, height, heart rate and mean arterial pressure. In multivariable-adjusted regression, we found an independent inverse association between PPA and age only in the black group (β=-0.18, P=0.002). PPA declines earlier with age in normotensive black adults younger than 30years, exemplifying early vascular aging which may predispose black in iduals to future cardiovascular outcomes.
Publisher: Springer Science and Business Media LLC
Date: 26-11-2015
DOI: 10.1038/HR.2015.123
Publisher: Elsevier BV
Date: 05-2021
Publisher: Elsevier BV
Date: 08-2014
DOI: 10.1016/J.NUMECD.2014.02.005
Abstract: Simple, low-cost central obesity measures may help identify in iduals with increased cardiometabolic disease risk, although it is unclear which measures perform best in African adults. We aimed to: 1) cross-sectionally compare the accuracy of existing waist-to-height ratio (WHtR) and waist circumference (WC) thresholds to identify in iduals with hypertension, pre-diabetes, or dyslipidaemia 2) identify optimal WC and WHtR thresholds to detect CVD risk in this African population and 3) assess which measure best predicts 5-year CVD risk. Black South Africans (577 men, 942 women, aged >30years) were recruited by random household selection from four North West Province communities. Demographic and anthropometric measures were taken. Recommended diagnostic thresholds (WC > 80 cm for women, >94 cm for men WHtR > 0.5) were evaluated to predict blood pressure, fasting blood glucose, lipids, and glycated haemoglobin measured at baseline and 5 year follow up. Women were significantly more overweight than men at baseline (mean body mass index (BMI) women 27.3 ± 7.4 kg/m(2), men 20.9 ± 4.3 kg/m(2)) median WC women 81.9 cm (interquartile range 61-103), men 74.7 cm (63-87 cm), all P 0.5 appears to be more consistently supported and may provide a better predictor of future cardiometabolic risk in sub-Saharan Africa.
Publisher: Wiley
Date: 13-01-2016
DOI: 10.1111/JCH.12768
Publisher: MDPI AG
Date: 20-04-2017
DOI: 10.3390/NU9040404
Publisher: Springer Science and Business Media LLC
Date: 29-01-2023
DOI: 10.1038/S41371-021-00653-X
Abstract: South Africa was among the first countries to adopt mandatory regulation in 2016 to lower the salt content in processed foods, aiming to reduce population salt intake to <5 g/day. To assess the effectiveness of this regulation in 20-30 year-old adults, we determined the change in salt intake over a mean follow-up time of 4.56-years spanning the implementation of the regulation. This observational study included baseline (2013-2016 N = 668 24.9 ± 3 years 47.8% black 40.7% men) and follow-up data (2018-ongoing N = 311 25.4 ± 3.05 years 51.1% black 43.4% men) for participants of the African-PREDICT study. Salt intake was estimated from 24-h urinary sodium excretion. Median salt intake at baseline (N = 668) was 7.88 g/day (IQR: 5.67). In those followed (N = 311), salt intake reduced from baseline [median (IQR): 7.91 g/day (5.83)] to follow-up [7.26 g/day (5.30)] [unadjusted median: -0.82 g/day]. After adjusting for baseline salt intake to address regression to the mean, the mean salt reduction was -1.2 g/day. The greatest reductions were in men [mean difference: -1.47 g/day], black adults [mean difference: -2.04 g/day], and participants from low [mean difference: -1.89 g/day] or middle [mean difference: -1.84 g/day] socio-economic status groups, adjusting for baseline salt intake. Our preliminary findings suggest that South Africa's salt regulation has been effective in lowering salt intake in young adults by ~1.2 g salt/day. Our study supports the effectiveness of upstream interventions to lower population salt intake, particularly for vulnerable groups who may typically consume more processed foods. It needs to be determined if the legislation has the anticipated population health gains.
Publisher: Springer Science and Business Media LLC
Date: 23-03-2017
DOI: 10.1038/JHH.2017.18
Abstract: Consistent reports indicate that hypertension is a particularly common finding in black populations. Hypertension occurs at younger ages and is often more severe in terms of blood pressure levels and organ damage than in whites, resulting in a higher incidence of cardiovascular disease and mortality. This review provides an outline of recent advances in the pathophysiological understanding of blood pressure elevation and the consequences thereof in black populations in Africa. This is set against the backdrop of populations undergoing demanding and rapid demographic transition, where infection with the human immunodeficiency virus predominates, and where under and over-nutrition coexist. Collectively, recent findings from Africa illustrate an increased lifetime risk to hypertension from foetal life onwards. From young ages black populations display early endothelial dysfunction, increased vascular tone and reactivity, microvascular structural adaptions as well as increased aortic stiffness resulting in elevated central and brachial blood pressures during the day and night, when compared to whites. Together with knowledge on the contributions of sympathetic activation and abnormal renal sodium handling, these pathophysiological adaptations result in subclinical and clinical organ damage at younger ages. This overall enhanced understanding on the determinants of blood pressure elevation in blacks encourages (a) novel approaches to assess and manage hypertension in Africa better, (b) further scientific discovery to develop more effective prevention and treatment strategies and
Publisher: Springer Science and Business Media LLC
Date: 29-09-2020
DOI: 10.1186/S40795-020-00379-Y
Abstract: Though Ghana has high hypertension prevalence, the country lacks current national salt consumption data required to build and enhance advocacy for salt reduction. We explored the characteristics of a randomly selected sub s le that had valid urine collection, along with matched survey, anthropometric and BP data ( n = 839, mean age = 60y), from the World Health Organization’s Study on global AGEing and adult health (WHO-SAGE), Ghana Wave 3, n = 3053). We also investigated the relationship between salt intake and blood pressure (BP) among the cohort. BP was measured in triplicate and 24 h urine was collected for the determination of urinary sodium (Na), potassium (K), creatinine (Cr) and iodine levels. Hypertension prevalence was 44.3%. Median salt intake was 8.3 g/day, higher in women compared to men (8.6, interquartile range (IQR) 7.5 g/day vs 7.5, IQR 7.4 g/day, p 0.01), younger participants (18–49 y) compared to older ones (50+ y) (9.7, IQR 7.9 g/day vs 8.1, IQR 7.1 g/day, p 0.01) and those with higher Body Mass Index (BMI) ( 30 kg/m 2 ) compared to a healthy BMI (18.5–24.9 kg/m 2 ) (10.04, IQR 5.1 g/day vs 6.2, IQR 5.6 g/day, p 0.01). More than three quarters (77%, n = 647) of participants had salt intakes above the WHO maximum recommendation of 5 g/d, and nearly two thirds (65%, n = 548) had daily K intakes below the recommended level of 90 mmol. Dietary sodium to potassium (Na: K) ratios above 2 mmol/mmol were positively associated with increasing BP with age. Population-based interventions to reduce salt intake and increase K consumption are needed.
Publisher: Elsevier BV
Date: 09-2017
Publisher: BMJ
Date: 11-2016
Publisher: Public Library of Science (PLoS)
Date: 08-01-2021
DOI: 10.1371/JOURNAL.PONE.0244807
Abstract: The prevalence of hypertension is increasing in low- and middle-income countries, however statistics are generally derived from cross sectional surveys that utilize different methodologies and population s les. We investigated blood pressure (BP) changes over 11–12 years in a large cohort of adults aged 50 years and older (n = 820) included in the World Health Organization’s Study on global AGEing and adult health (WHO-SAGE Ghana) Wave 1 (2007/8) with follow up in Wave 3 (2019). Participants’ BP were measured in triplicate and a survey completed at both time points. Survey instruments collected information on sociodemographic characteristics, lifestyle, health behaviors and chronic conditions. While no significant difference was found in systolic BP between Waves 1 and 3, diastolic BP decreased by 9.7mmHg (mean = 88.6, 15.4 to 78.9, 13.6 respectively) and pulse pressure increased by 9.5mmHg (44.8, 13.7 to 54.3, 14.1). Awareness of hypertension increased by 37%, from (20% to 57%), but no differences were found for the proportion of hypertensives receiving treatment nor those that had controlled BP. Mixed effects modelling showed a decrease in diastolic BP was associated with increasing age, living in rural areas and having health insurance. Factors associated with an increased awareness of hypertension were residing in urban areas, having health insurance and increasing body mass index. While diagnosis of hypertension has improved over time in Ghana, there is an ongoing need to improve its treatment in older adults.
Publisher: Springer Science and Business Media LLC
Date: 31-10-2019
Publisher: Wiley
Date: 15-12-2015
DOI: 10.1111/JCH.12455
Publisher: Oxford University Press (OUP)
Date: 22-11-2018
Publisher: MDPI AG
Date: 28-08-2017
DOI: 10.3390/NU9090939
Publisher: Springer Science and Business Media LLC
Date: 14-01-2016
Publisher: Wiley
Date: 03-07-2019
DOI: 10.1111/JCH.13586
Publisher: American Scientific Publishers
Date: 2016
Abstract: Fe₃O₄ films were prepared by electrodeposition under varying preparation conditions (current density, temperature, and time). The electrodeposited Fe₃O₄ were characterized in terms of morphology and composition using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The electrodeposited films were also tested as anode in coin cell systems. Fluoroethylene carbonate (FEC) electrolyte was found to improve the battery performance due to formation of a better solid electrolyte interface (SEI). Conducting polymer of polypyrrole (PPY) was coated on the surface of Fe₃O₄ films for the first time with the aim to improve the electric conductivity and to buffer volume expansion of Fe₃O₄ films.
Publisher: Elsevier BV
Date: 02-2019
Publisher: Wiley
Date: 07-2018
DOI: 10.1111/JCH.13329
Publisher: Oxford University Press (OUP)
Date: 10-02-2014
DOI: 10.1093/AJH/HPT288
Abstract: Increased urinary albumin excretion reflects general vascular damage and predicts adverse cardiovascular and renal outcomes. Albuminuria can be determined from easily collected spot urine s les, especially in low-resource settings. However, no prognostic evidence exists for Africans. We followed clinical outcomes in 1,061 randomly selected non diabetic, human immunodeficiency virus (HIV)-negative Africans (mean age: 51.5 years 62.0% women). Baseline urinary albumin-to-creatinine ratio was assessed from spot urine s les. Over a median follow-up of 4.52 years, 132 deaths occurred, of which 47 were cardiovascular related. The urinary albumin-to-creatinine ratio averaged 6.1 μg/mg (5th to 95th percentile interval 1.2-70.0). In multivariable-adjusted analyses, urinary albumin excretion predicted all-cause mortality (hazard ratio (HR), 1.26 95% confidence interval (CI), 1.07-1.48 P = 0.006), and a tendency existed for cardiovascular mortality (HR, 1.26 95% CI, 0.97-1.63 P = 0.087), which seemed to be driven by fatal stroke (HR, 1.72 95% CI, 1.17-2.54 P = 0.006) rather than cardiac mortality (HR, 0.67 95% CI, 0.41-1.07 P = 0.094). The predictive value remained in 528 hypertensives for both all-cause (HR, 1.38 95% CI, 1.13-1.69 P = 0.001) and cardiovascular (HR, 1.45 95% CI, 1.07-1.96 P = 0.017) mortality, again driven by stroke. Our findings also remained significant after we excluded participants with macroalbuminuria, those on antihypertensive treatment, as well as participants who died within 1 year after enrollment. In nondiabetic HIV-negative Africans, albuminuria predicts all-cause and stroke mortality.
Publisher: MDPI AG
Date: 07-06-2018
DOI: 10.3390/NU10060736
Publisher: MDPI AG
Date: 08-07-2020
DOI: 10.3390/NU12072026
Abstract: Given a global focus on salt reduction efforts to reduce cardiovascular risk, it is important to obtain accurate measures of salt intake on a population level. This study determined firstly whether adjustment for intra-in idual variation in urinary sodium (Na) excretion using three repeated 24 h collections affects daily estimates and whether the use of repeated spot urine s les results in better prediction of 24 h Na compared to a single collection. Twenty three community-dwelling men and women from South Africa (mean age 59.7 years (SD = 15.6)) participating in the World Health Organization Study on global AGEing and adult health (WHO-SAGE) Wave 3 study collected 24 h and spot early morning urine s les over three consecutive days to assess urinary Na excretion. INTERSALT, Tanaka, and Kawasaki prediction equations, with either average or adjusted spot Na values, were used to estimate 24 h Na and compared these against measured 24 h urinary Na. Adjustment was performed by using the ratio of between-person (sb) and total (sobs) variability obtained from repeated measures analysis of variance. Sensitivity of the equations to predict daily urinary Na values below 5 g salt equivalent was calculated. The sb/sobs for urinary Na using three repeated s les for spot and 24 h s les were 0.706 and 0.798, respectively. Correction using analysis of variance for 3 × 24 h collections resulted in contraction of the upper end of the distribution curve (90th centile: 157 to 136 mmoL/day 95th centile: 220 to 178 mmoL/day). All three prediction equations grossly over-estimated 24 h urinary Na excretion, regardless of whether a single spot urine or repeated collections corrected for intra-in idual variation were used. Sensitivity of equations to detect salt intake equivalent values of ≤5 g/day was 13% for INTERSALT, while the other two equations had zero sensitivity. Correcting for intra-in idual variability in Na excretion using three 24 h urine collections contracted the distribution curve for high intakes. Repeated collection of spot s les for urinary Na analysis does not improve the accuracy of predicting 24 h Na excretion. Spot urine s les are not appropriate to detect participants with salt intakes below the recommended 5 g/day.
Publisher: Springer Science and Business Media LLC
Date: 10-05-2019
DOI: 10.1038/S41371-019-0210-2
Abstract: Repeated 24-hour urine collection is considered to be the gold standard for assessing salt intake. This is often impractical in large-population studies, especially in low–middle-income countries. Equations to estimate 24-hour urinary salt excretion from a spot urine s le have been developed, but have not been widely validated in African populations. This study aimed to systematically assess the validity of four existing equations to predict 24-hour urinary sodium excretion (24UNa) from spot urine s les in a nationally representative s le of South Africans. Spot and 24-hour urine s les were collected in a subs le ( n = 438) of participants from the World Health Organisation Study on global AGEing and adult health (SAGE) Wave 2 in South Africa in 2015. Measured 24UNa values were compared with predicted 24UNa values from the Kawasaki, Tanaka, INTERSALT and Mage equations using Bland–Altman plots. In this subs le (mean age 52.8 ± 16.4 years body mass index 30.2 ± 8.2 kg/m 2 76% female 73% black African 42% hypertensive), all four equations produced a significantly different population estimate compared with the measured median value of 6.7 g salt/day (IQR 4.4–10.5). Although INTERSALT underestimated salt intake (−3.77 g/d −1.64 to −7.09), the other equations overestimated by 1.28 g/d (−3.52 1.97), 6.24 g/d (2.22 9.45), and 17.18 g/d (8.42 31.96) for Tanaka, Kawasaki, and Mage, respectively. Bland–Altman curves indicated unacceptably wide levels of agreement. Use of these equations to estimate population level salt intake from spot urine s les in South Africans is not recommended.
Publisher: MDPI AG
Date: 05-01-2021
Abstract: Recent studies have suggested the common co-occurrence of hypertension and diabetes in South Africa. Given that hypertension and diabetes are known to share common socio-demographic, anthropometric and lifestyle risk factors, the aim of this study was to jointly model the shared and disease-specific geographical variation of hypertension and diabetes. The current analysis used the Study on Global Ageing and Adult Health (SAGE) South Africa Wave 2 (2014/15) data collected from 2761 participants. Of the 2761 adults (median age = 56 years), 641 (23.2%) had high blood pressure on measurement and 338 (12.3%) reported being diagnosed with diabetes. The shared component has distinct spatial patterns with higher values of odds in the eastern districts of Kwa-Zulu Natal and central Gauteng province. The shared component may represent unmeasured health behavior characteristics or the social determinants of health in our population. Our study further showed how a shared component (latent and unmeasured health behavior characteristics or the social determinants of health) is distributed across South Africa among the older adult population. Further research using similar shared joint models may focus on extending these models for multiple diseases with ecological factors and also incorporating s ling weights in the spatial analyses.
Publisher: BMJ
Date: 03-2018
DOI: 10.1136/BMJOPEN-2017-020404
Abstract: The WHO’s global targets for non-communicable disease reduction recommend consumption of g salt/day. In 2016, South Africa was the first country to legislate maximum salt levels in processed foods. South Africa’s salt iodisation fortification programme has successfully addressed iodine deficiency but information is dated. Simultaneous monitoring of sodium reduction and iodine status is required to ensure compatibility of the two public health interventions. A nested cohort design within WHO’s 2015 Study on global AGEing and adult health (n=2887) including in iduals from households across South Africa. Randomly selected adults (n=875) provided 24-hour and spot urine s les for sodium and iodine concentration analysis (the primary and secondary outcome measures, respectively). Median 24-hour urinary iodine excretion (UIE) and spot urinary iodine concentrations (UIC) were compared by salt intakes of g/day, 5–9g/dayand g/day. Median daily sodium excretion was equivalent to 6.3 g salt/day (range 1–43 g/day) 35% had urinary sodium excretion values within the desirable range ( g salt/day), 37% had high values (5–9 g salt/day) and 28% had very high values ( g salt/day). Median UIC was 130 µg/L (IQR=58–202), indicating population iodine sufficiency (≥100 µg/L). Both UIC and UIE differed across salt intake categories (p .001) and were positively correlated with estimated salt intake (r=0.166 and 0.552, respectively both p .001). Participants with salt intakes of g/day were not meeting the Estimated Average Requirement for iodine intake (95 µg/day). In a nationally representative s le of South African adults, the association between indicators of population iodine status (UIC and UIE) and salt intake, estimated using 24-hour urinary sodium excretion, indicate that low salt intakes may compromise adequacy of iodine intakes in a country with mandatory iodisation of table salt. The iodine status of populations undergoing salt reduction strategies needs to be closely monitored to prevent re-emergence of iodine deficiency.
Publisher: Georg Thieme Verlag KG
Date: 08-10-2014
Abstract: Severe underweight may be a risk factor for hypertension in developing countries, although the manner whereby this occurs is unknown. Leptin is known to exert both beneficial and detrimental vascular effects, and is predictive of poor cardiovascular outcome at high levels, but also at low levels. We explored the relationship between blood pressure and leptin in black men from South Africa with a body mass index (BMI) in the underweight to normal range. We included 113 African men (BMI≤25 kg/m(2)) and took anthropometric, biochemical and cardiovascular measures. The blood pressure-leptin relationship was then investigated along quintiles of leptin and within BMI stratified median split (20 kg/m(2)) groups. Blood pressure increased across leptin quintiles 1-3 (p for trend≤0.040), whereas no relationship was observed along quintiles 3 to 5 (p for trend≥0.14) (adjusted for age and waist circumference). Blood pressure was similar in the two BMI median split groups (p≥0.083). In the low BMI group only, blood pressure associated positively with leptin following unadjusted, partial, and full adjustment (systolic blood pressure and diastolic blood pressure: R(2)=0.20-0.27, β=0.32-0.34, p≤0.009). Decreasing leptin levels are not likely to contribute to hypertension prevalence in the underweight. Rather, in African men with a BMI≤20 kg/m(2), low leptin levels are positively and independently associated with elevated blood pressure, which is not seen at higher BMI (20-25 kg/m(2)). Our findings suggest a differential concentration dependent vascular effect of leptin in underweight and normal weight African men.
Publisher: Cambridge University Press (CUP)
Date: 05-10-2017
Publisher: Elsevier BV
Date: 02-2015
DOI: 10.1016/J.JASH.2014.12.003
Abstract: Evidence of the relationship between left ventricular hypertrophy and urinary albumin excretion is contradictory and limited in black adults in whom hypertensive heart disease is common. We aimed to investigate the relationship between subclinical left ventricular hypertrophy and albuminuria in non-diabetic hypertensive blacks. Urinary albumin-to-creatinine ratio (UACR) was determined from 8-hour overnight urine collection. We recorded ambulatory blood pressure and 12-lead electrocardiogram during a typical working day. Cornell product (P = .002), UACR (P = .042), 24-hour systolic pressure (P < .0001), and 24-hour pulse pressure (P < .0001) were higher in the hypertensive group. Cornell product was associated with UACR in single (r = 0.25 P = .012), partial (P trend = .002), and multiple regression (β = 0.326 P = .0005) analyses in the hypertensive group only, even below the threshold for microalbuminuria and independent of 24-hour systolic pressure. Urinary albumin excretion is associated with subclinical left ventricular hypertrophy in non-diabetic hypertensive blacks and may be a useful marker of early cardiovascular disease in blacks.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 2022
DOI: 10.1161/HYPERTENSIONAHA.121.17765
Abstract: Central (aortic) systolic blood pressure (cSBP) is the pressure seen by the heart, the brain, and the kidneys. If properly measured, cSBP is closer associated with hypertension-mediated organ damage and prognosis, as compared with brachial SBP (bSBP). We investigated 24-hour profiles of bSBP and cSBP, measured simultaneously using Mobilograph devices, in 2423 untreated adults (1275 women age, 18–94 years), free from overt cardiovascular disease, aiming to develop reference values and to analyze daytime-nighttime variability. Central SBP was assessed, using brachial waveforms, calibrated with mean arterial pressure (MAP)/diastolic BP (cSBP MAP/DBPcal ), or bSBP/diastolic blood pressure (cSBP SBP/DBPcal ), and a validated transfer function, resulting in 144 509 valid brachial and 130 804 valid central measurements. Averaged 24-hour, daytime, and nighttime brachial BP across all in iduals was 124/79, 126/81, and 116/72 mm Hg, respectively. Averaged 24-hour, daytime, and nighttime values for cSBP MAP/DBPcal were 128, 128, and 125 mm Hg and 115, 117, and 107 mm Hg for cSBP SBP/DBPcal , respectively. We pragmatically propose as upper normal limit for 24-hour cSBP MAP/DBPcal 135 mm Hg and for 24-hour cSBP SBP/DBPcal 120 mm Hg. bSBP dipping (nighttime-daytime/daytime SBP) was −10.6 % in young participants and decreased with increasing age. Central SBP SBP/DBPcal dipping was less pronounced (−8.7% in young participants). In contrast, cSBP MAP/DBPcal dipping was completely absent in the youngest age group and less pronounced in all other participants. These data may serve for comparison in various diseases and have potential implications for refining hypertension diagnosis and management. The different dipping behavior of bSBP versus cSBP requires further investigation.
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: No location found
No related grants have been discovered for Lisa J Ware.