Browsing by Subject "Blood pressure"
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- ItemOpen AccessA food-based dietary strategy lowers blood pressure in a low socio-economic setting: a randomised study in South Africa(2008) Charlton, Karen E; Steyn, Krisela; Levitt, Naomi S; Peer, Nasheeta; Jonathan, Deborah; Gogela, Theresa; Rossouw, Katja; Gwebushe, Nomonde; Lombard, Carl JOBJECTIVE: To assess the impact of a food-based intervention on blood pressure (BP) in free-living South African men and women aged 50-75 years, with drug-treated mild-to-moderate hypertension. METHODS: A double-blind controlled trial was undertaken in eighty drug-treated mild-to-moderate hypertensive subjects randomised to an intervention (n 40) or control (n 40) arm. The intervention was 8-week provision of six food items with a modified cation content (salt replacement (SOLO ), bread, margarine, stock cubes, soup mix and a flavour enhancer) and 500 ml of maas (fermented milk)/d. The control diet provided the same quantities of the targeted foods but of standard commercial composition and 500 ml/d of artificially sweetened cooldrink. FINDINGS: The intervention effect estimated as the contrast of the within-diet group changes in BP from baseline to post-intervention was a significant reduction of 6.2 mmHg (95 % CI 0.9, 11.4) for systolic BP. The largest intervention effect in 24 h BP was for wake systolic BP with a reduction of 5.1 mmHg (95 % CI 0.4, 9.9). For wake diastolic BP the reduction was 2.7 mmHg (95 % CI -0.2, 5.6). CONCLUSIONS: Modification of the cation content of a limited number of commonly consumed foods lowers BP by a clinically significant magnitude in treated South African hypertensive patients of low socio-economic status. The magnitude of BP reduction provides motivation for a public health strategy that could be adopted through lobbying of the food industry by consumer and health agencies.
- ItemOpen AccessAnaemia, haemoglobin level and cause-specific mortality in people with and without diabetes(Public Library of Science, 2012) Kengne, Andre Pascal; Czernichow, Sébastien; Hamer, Mark; Batty, G David; Stamatakis, EmmanuelBACKGROUND: Both anaemia and cardiovascular disease (CVD) are common in people with diabetes. While individually both characteristics are known to raise mortality risk, their combined influence has yet to be quantified. In this pooling project, we examined the combined impact of baseline haemoglobin levels and existing CVD on all-cause and CVD mortality in people with diabetes. We draw comparison of these effects with those apparent in diabetes-free individuals. Methods/Principal FINDINGS: A combined analyses of 7 UK population-based cohorts resulted in 26,480 study members. There were 946 participants with physician-diagnosed diabetes, 2227 with anaemia [haemoglobin<13 g/dl (men) or <12 (women)], 2592 with existing CVD (stroke, ischaemic heart disease), and 21,396 with none of the conditions. Across diabetes and anaemia subgroups, and using diabetes-free, non-anaemic participants as the referent group, the adjusted hazard ratios (HR) were 1.46 (95% CI: 1.30-1.63) for anaemia, 1.67 (1.45-1.92) for diabetes, and 2.10 (1.55-2.85) for diabetes and anaemia combined. Across combined diabetes, anaemia and CVD subgroups, and compared with non-anaemic, diabetes-free and CVD-free participants, HR (95% CI) for all-cause mortality were 1.49 (1.32-1.69) anaemia, 1.60 (1.46-1.76) for existing CVD, and 1.66 (1.39-1.97) for diabetes alone. Equivalents were 2.13 (1.48-3.07) for anaemia and diabetes, 2.68 (2.14-3.36) for diabetes and existing CVD, and 3.25 (1.88-5.62) for the three combined. Patterns were similar for CVD mortality. Conclusions/Significance Individually, anaemia and CVD confer similar mortality risks in people with diabetes, and are excessively fatal in combination. Screening for anaemia would identify vulnerable diabetic patients whose outcomes can potentially be improved.
- ItemOpen AccessBlood pressure gradients and cardiovascular risk factors in urban and rural populations in Abia State South Eastern Nigeria using the WHO STEPwise approach(Public Library of Science, 2013) Okpechi, Ikechi Gareth; Chukwuonye, Innocent Ijezie; Tiffin, Nicki; Madukwe, Okechukwu Ojoemelam; Onyeonoro, Ugochukwu Uchenna; Umeizudike, Theophilus Ifeanyichukwu; Ogah, Okechukwu SamuelBACKGROUND: Developing countries of sub-Saharan Africa (SSA) face a double burden of non-communicable diseases (NCDs) and communicable diseases. As high blood pressure (BP) is a common global cardiovascular (CV) disorder associated with high morbidity and mortality, the relationship between gradients of BP and other CV risk factors was assessed in Abia State, Nigeria. METHODS: Using the WHO STEPwise approach to surveillance of chronic disease risk factors, we conducted a population-based cross-sectional survey in Abia state, Nigeria from August 2011 to March 2012. Data collected at various steps included: demographic and behavioral risk factors (Step 1); BP and anthropometric measurements (Step 2), and fasting blood cholesterol and glucose (Step 3). RESULTS: Of the 2983 subjects with complete data for analysis, 52.1% were females and 53.2% were rural dwellers. Overall, the distribution of selected CV disease risk factors was diabetes (3.6%), hypertension (31.4%), cigarette smoking (13.3%), use of smokeless tobacco (4.8%), physical inactivity (64.2%) and being overweight or obese (33.7%). Presence of hypertension, excessive intake of alcohol, smoking (cigarette and smokeless tobacco) and physical inactivity occurred more frequently in males than in females (p<0.05); while low income, lack of any formal education and use of smokeless tobacco were seen more frequently in rural dwellers than in those living in urban areas (p<0.05). The frequency of selected CV risk factors increased as BP was graded from optimal, normal to hypertension; and high BP correlated with age, gender, smokeless tobacco, overweight or obesity, annual income and level of education. CONCLUSION: Given the high prevalence of hypertension in this part of Nigeria, there is an urgent need to focus on the reduction of preventable CV risk factors we have observed to be associated with hypertension, in order to effectively reduce the burden of NCDs in Africa.
- ItemOpen AccessChanges in blood pressure, glucose levels, insulin secretion and anthropometry after long term exposure to antiretroviral therapy in South African women(2015-08-05) Abrahams, Zulfa; Dave, Joel A; Maartens, Gary; Levitt, Naomi SAbstract Background A number of metabolic abnormalities, such as dysglycaemia, insulin resistance, lipodystrophy and dyslipidaemia, are associated with the use of antiretroviral drugs. We aimed to assess the effects of long-term antiretroviral exposure on blood pressure, glycaemia, insulin secretion and anthropometric measures in black South African women. Methods A convenience sample of HIV-infected women on first-line ART for a median of 16 months at baseline, had the following evaluations twice, at baseline and after approximately 5 years: anthropometry, including skin fold thicknesses, blood pressure, oral glucose test, and insulin. Insulin sensitivity and secretion (HOMA-IR, IGI and DIo) were estimated. Results At baseline more than half the 103 women were using stavudine and efavirenz. The median interval between baseline and follow-up evaluation was 66 months. Weight, waist circumference, and waist-hip ratio increased over time, while limb skinfold thickness decreased over time. Systolic and diastolic blood pressure increased significantly and the proportion of participants with hypertension increased from 3.9 to 15.5% (p < 0.001). There were increases from baseline in plasma glucose concentrations at 30 and 120 min; insulin concentrations at 0 and 30 min; and IGI and DIo. The proportion of participants with diabetes increased from 1 to 7.5% (p = 0.070). Conclusion In black South African women with long-term exposure to ART, increases in hypertension and possibly diabetes were observed. Participants experienced an increase in central fat and a decrease in peripheral fat distribution. Early identification and management of these metabolic changes are important, especially in a region with the highest HIV-infected population in the world.
- ItemOpen AccessCommon variation neighbouring micro-RNA 22 is associated with increased left ventricular mass(Public Library of Science, 2013) Harper, Andrew R; Mayosi, Bongani M; Rodriguez, Antony; Rahman, Thahira; Hall, Darroch; Mamasoula, Chrysovalanto; Avery, Peter J; Keavney, Bernard DAIMS: Previous genome-wide linkage analysis has suggested that chromosomal region 17p13.3 may harbour genes influencing left ventricular mass (LVM) in man. To date, the genetic factors accounting for LVM variability remain largely unknown but a non-coding RNA gene within this region, micro-RNA 22 (miR-22) , has been implicated in cardiac hypertrophy and heart failure in animal models. We thus investigated the relationship between common genetic polymorphisms surrounding miR-22 and left ventricular mass in a family-based association study. Methods and RESULTS: We studied a cohort of 255 families comprising 1,425 individuals ascertained via a hypertensive proband. Ten single nucleotide polymorphisms which together tagged common genetic variation surrounding the miR-22 gene were genotyped. There was evidence of association between the rs7223247 polymorphism, which lies within the 3′UTR of a gene of unknown function, TLCD2, immediately downstream from miR-22, and left ventricular mass determined by Sokolow-Lyon voltage (Bonferroni corrected p- value = 0.038). The T allele at rs7223247 was associated with an 0.272 standard deviation higher Sokolow-Lyon voltage. Genotype was responsible for ∼1% of the population variability in LVM. CONCLUSIONS: Genotype at the rs7223247 polymorphism affects left ventricular mass determined by Sokolow-Lyon voltage. The neighbouring genes miR-22 and TLCD2 are strong candidates to account for this observation.
- ItemOpen AccessComputational analysis of candidate disease genes and variants for salt-sensitive hypertension in indigenous Southern Africans(Public Library of Science, 2010) Tiffin, Nicki; Meintjes, Ayton; Ramesar, Rajkumar; Bajic, Vladimir B.; Rayner, BrianMultiple factors underlie susceptibility to essential hypertension, including a significant genetic and ethnic component, and environmental effects. Blood pressure response of hypertensive individuals to salt is heterogeneous, but salt sensitivity appears more prevalent in people of indigenous African origin. The underlying genetics of salt-sensitive hypertension, however, are poorly understood. In this study, computational methods including text- and data-mining have been used to select and prioritize candidate aetiological genes for salt-sensitive hypertension. Additionally, we have compared allele frequencies and copy number variation for single nucleotide polymorphisms in candidate genes between indigenous Southern African and Caucasian populations, with the aim of identifying candidate genes with significant variability between the population groups: identifying genetic variability between population groups can exploit ethnic differences in disease prevalence to aid with prioritisation of good candidate genes. Our top-ranking candidate genes include parathyroid hormone precursor ( PTH ) and type-1angiotensin II receptor ( AGTR1 ). We propose that the candidate genes identified in this study warrant further investigation as potential aetiological genes for salt-sensitive hypertension.
- ItemOpen AccessEffects of different missing data imputation techniques on the performance of undiagnosed diabetes risk prediction models in a mixed-ancestry population of South Africa(Public Library of Science, 2015) Masconi, Katya L; Matsha, Tandi E; Erasmus, Rajiv T; Kengne, Andre PBACKGROUND: Imputation techniques used to handle missing data are based on the principle of replacement. It is widely advocated that multiple imputation is superior to other imputation methods, however studies have suggested that simple methods for filling missing data can be just as accurate as complex methods. The objective of this study was to implement a number of simple and more complex imputation methods, and assess the effect of these techniques on the performance of undiagnosed diabetes risk prediction models during external validation. METHODS: Data from the Cape Town Bellville-South cohort served as the basis for this study. Imputation methods and models were identified via recent systematic reviews. Models’ discrimination was assessed and compared using C-statistic and non-parametric methods, before and after recalibration through simple intercept adjustment. RESULTS: The study sample consisted of 1256 individuals, of whom 173 were excluded due to previously diagnosed diabetes. Of the final 1083 individuals, 329 (30.4%) had missing data. Family history had the highest proportion of missing data (25%). Imputation of the outcome, undiagnosed diabetes, was highest in stochastic regression imputation (163 individuals). Overall, deletion resulted in the lowest model performances while simple imputation yielded the highest C-statistic for the Cambridge Diabetes Risk model, Kuwaiti Risk model, Omani Diabetes Risk model and Rotterdam Predictive model. Multiple imputation only yielded the highest C-statistic for the Rotterdam Predictive model, which were matched by simpler imputation methods. CONCLUSIONS: Deletion was confirmed as a poor technique for handling missing data. However, despite the emphasized disadvantages of simpler imputation methods, this study showed that implementing these methods results in similar predictive utility for undiagnosed diabetes when compared to multiple imputation.
- ItemOpen AccessGenotype at the P554L variant of the hexose-6 phosphate dehydrogenase gene is associated with carotid intima-medial thickness(Public Library of Science, 2011) Rahman, Thahira J; Walker, Elizabeth A; Mayosi, Bongani M; Hall, Darroch H; Avery, Peter J; Connell, John M C; Watkins, Hugh; Stewart, Paul M; Keavney, BernardObjective The combined thickness of the intima and media of the carotid artery (carotid intima-medial thickness, CIMT) is associated with cardiovascular disease and stroke. Previous studies indicate that carotid intima-medial thickness is a significantly heritable phenotype, but the responsible genes are largely unknown. Hexose-6 phosphate dehydrogenase (H6PDH) is a microsomal enzyme whose activity regulates corticosteroid metabolism in the liver and adipose tissue; variability in measures of corticosteroid metabolism within the normal range have been associated with risk factors for cardiovascular disease. We performed a genetic association study in 854 members of 224 families to assess the relationship between polymorphisms in the gene coding for hexose-6 phosphate dehydrogenase (H6PD) and carotid intima-medial thickness. METHODS: Families were ascertained via a hypertensive proband. CIMT was measured using B-mode ultrasound. Single nucleotide polymorphisms (SNPs) tagging common variation in the H6PD gene were genotyped. Association was assessed following adjustment for significant covariates including "classical" cardiovascular risk factors. Functional studies to determine the effect of particular SNPs on H6PDH were performed. RESULTS: There was evidence of association between the single nucleotide polymorphism rs17368528 in exon five of the H6PD gene, which encodes an amino-acid change from proline to leucine in the H6PDH protein, and mean carotid intima-medial thickness (p = 0.00065). Genotype was associated with a 5% (or 0.04 mm) higher mean carotid intima-medial thickness measurement per allele, and determined 2% of the population variability in the phenotype. CONCLUSIONS: Our results suggest a novel role for the H6PD gene in atherosclerosis susceptibility.
- ItemOpen AccessIndependent association of resting energy expenditure with blood pressure: confirmation in populations of the African diaspora(2018) Dugas, Lara RObesity is a major risk factor for hypertension, however, the physiologic mechanisms linking increased adiposity to elevations in blood pressure are not well described. An increase in resting energy expenditure (REE) is an obligatory consequence of obesity. Previous survey research has demonstrated that REE is an independent predictor of blood pressure, and eliminates the co-linear association of body mass index. This observation has received little attention and there have been no attempts to provide a causal explanation.
- ItemOpen AccessIndependent association of resting energy expenditure with blood pressure: confirmation in populations of the African diaspora(BioMed Central, 2018-01-10) Creber, Chloe; Cooper, Richard S; Plange-Rhule, Jacob; Bovet, Pascal; Lambert, Estelle V; Forrester, Terrence E; Schoeller, Dale; Riesen, Walter; Korte, Wolfgang; Cao, Guichan; Luke, Amy; Dugas, Lara RBackground: Obesity is a major risk factor for hypertension, however, the physiologic mechanisms linking increased adiposity to elevations in blood pressure are not well described. An increase in resting energy expenditure (REE) is an obligatory consequence of obesity. Previous survey research has demonstrated that REE is an independent predictor of blood pressure, and eliminates the co-linear association of body mass index. This observation has received little attention and there have been no attempts to provide a causal explanation. Methods: At baseline in an international comparative study on obesity, 289 participants aged 25–44 were recruited from communities in the US, the Seychelles, Ghana and South Africa and had REE measured with indirect calorimetry. All participants were thought to be free of major illness. Results: In multivariate regression models, both systolic and diastolic blood pressure were positively associated with REE (p < 0.01), while body mass index and fat mass were negatively correlated with systolic blood pressure (p < 0.01, and p < 0.05 respectively), but not diastolic blood pressure. Conclusions: These data confirm previous reports and suggest that a common physiologic abnormality links REE and blood pressure. Elevated catecholamines, a putative metabolic characteristic of obesity, is a possible candidate to explain this association. The direct role of excess adipose tissue is open to question.
- ItemOpen AccessMetabolic syndrome and fatal outcomes in the post-stroke event: a 5-year cohort study in Cameroon(Public Library of Science, 2013) Balti, Eric Vounsia; Kengne, André Pascal; Fokouo, Jean Valentin Fogha; Nouthé, Brice Enid; Sobngwi, EugeneBackground and Purpose: Determinants of post-acute stroke outcomes in Africa have been less investigated. We assessed the association of metabolic syndrome (MetS) and insulin resistance with post-stroke mortality in patients with first-ever-in-lifetime stroke in the capital city of Cameroon (sub-Saharan Africa). METHODS: Patients with an acute first-stroke event (n = 57) were recruited between May and October 2006, and followed for 5 years for mortality outcome. MetS definition was based on the Joint Interim Statement 2009, insulin sensitivity/resistance assessed via glucose-to-insulin ratio, quantitative insulin sensitivity check index and homeostatic model assessment. RESULTS: Overall, 24 (42%) patients deceased during follow-up. The prevalence of MetS was higher in patients who died after 28 days, 1 year and 5 years from any cause or cardiovascular-related causes (all p≤ 0.040). MetS was associated with an increased overall mortality both after 1 year (39% vs. 9%) and 5 years of follow-up (55% vs. 26%, p = 0.022). Similarly, fatal events due to cardiovascular-related conditions were more frequent in the presence of MetS both 1 year (37% vs. 9%) and 5 years after the first-ever-in-lifetime stroke (43% vs. 13%, p = 0.017). Unlike biochemical measures of insulin sensitivity and resistance (non-significant), in age- and sex-adjusted Cox models, MetS was associated with hazard ratio (95% CI) of 2.63 (1.03-6.73) and 3.54 (1.00-12.56) respectively for all-cause and cardiovascular mortality 5 years after stroke onset. CONCLUSION: The Joint Interim Statement 2009 definition of MetS may aid the identification of a subgroup of black African stroke patients who may benefit from intensification of risk factor management.
- ItemOpen AccessOptimal waist-to-height ratio values for cardiometabolic risk screening in an ethnically diverse sample of South African urban and rural school boys and girls(Public Library of Science, 2013) Matsha, Tandi E; Kengne, Andre-Pascal; Yako, Yandiswa Y; Hon, Gloudina M; Hassan, Mogamat S; Erasmus, Rajiv TBACKGROUND: The proposed waist-to-height ratio (WHtR) cut-off of 0.5 is less optimal for cardiometabolic risk screening in children in many settings. The purpose of this study was to determine the optimal WHtR for children from South Africa, and investigate variations by gender, ethnicity and residence in the achieved value. METHODS: Metabolic syndrome (MetS) components were measured in 1272 randomly selected learners, aged 10-16 years, comprising of 446 black Africans, 696 mixed-ancestry and 130 Caucasians. The Youden's index and the closest-top-left (CTL) point approaches were used to derive WHtR cut-offs for diagnosing any two MetS components, excluding the waist circumference. RESULTS: The two approaches yielded similar cut-off in girls, 0.465 (sensitivity 50.0, specificity 69.5), but two different values in boys, 0.455 (42.9, 88.4) and 0.425 (60.3, 67.7) based on the Youden's index and the CTL point, respectively. Furthermore, WHtR cut-off values derived differed substantially amongst the regions and ethnic groups investigated, whereby the highest cut-off was observed in semi-rural and white children, respectively, Youden's index0.505 (31.6, 87.1) and CTL point 0.475 (44.4, 75.9). CONCLUSION: The WHtR cut-off of 0.5 is less accurate for screening cardiovascular risk in South African children. The optimal value in this setting is likely gender and ethnicity-specific and sensitive to urbanization.
- ItemOpen AccessOutcome of patients with primary immune-complex type Mesangiocapillary Glomerulonephritis (MCGN) in Cape Town South Africa(Public Library of Science, 2014) Okpechi, Ikechi G; Dlamini, Thandiwe A L; Duffield, Maureen; Rayner, Brian L; Moturi, George; Swanepoel, Charles RBackground and Aim Mesangiocapillary glomerulonephritis (MCGN) is a common cause of chronic kidney disease in developing countries. Data on the renal outcome of patients with idiopathic MCGN is limited. The aim of this study is to investigate the outcome of patients with idiopathic MCGN presenting to the Groote Schuur Hospital (GSH) Renal Unit in Cape Town. Materials and METHODS: A retrospective study of patients with idiopathic MCGN followed up at our clinic. Seventy-nine patients with no identifiable cause of MCGN were included for analysis. A composite renal outcome of persistent doubling of serum creatinine or end stage renal disease (ESRD) was used. Kaplan Meier survival and Cox regression analysis were used to assess survival and identify factors predicting the outcome. RESULTS: The mean age at biopsy was 33.9±13.6 years and 41.8% were black. Mean duration of follow up was 13.5±18.8 months. Twenty-three patients (34.2%) reached the composite endpoint. Overall, median renal survival was 38.7±11.7 months (95% CI 15.7-61.8) with 2-year and 5-year renal survival of 61% and 40.3% respectively. No significant difference was found for renal survival between males and females, treatment or non-treatment with immunosuppression, presence or absence of crescents or histological type of MCGN (p>0.05). On univariate Cox-regression analysis, factors found to be associated with the outcome were the estimated glomerular filtration rate at biopsy (OR 0.97 [95%CI: 0.95-0.99], p<0.0001), black race (OR 3.03 [95%CI: 1.27-7.21], p = 0.012) and presence of interstitial fibrosis in the biopsy (OR 2.64 [95%CI: 1.07-6.48], p = 0.034). Age, systolic blood pressure and attaining complete or partial remission approached significant values with the endpoint. CONCLUSIONS: The outcome of idiopathic MCGN in Cape Town is poor and requires further prospective studies to improve our understanding of this common disease.
- ItemOpen AccessPolymorphisms in the non-muscle myosin heavy chain gene (MYH9) are associated with lower glomerular filtration rate in mixed ancestry diabetic subjects from South Africa(Public Library of Science, 2012) Matsha, Tandi Edith; Masconi, Katya; Yako, Yandiswa Yolanda; Hassan, Mogamat Shafick; Macharia, Muiriri; Erasmus, Rajiv Timothy; Kengne, Andre PascalObjective: Though single nucleotide polymorphisms (SNPs) in the non-muscle myosin gene (MYH9) have been reported to explain most of the excess risk of nondiabetic chronic kidney disease (CKD), in African-Americans, some studies have also shown associations with diabetic end-stage renal disease. We investigated the association of MYH9 SNPs with renal traits in a mixed-ancestry South African population prone to diabetes. Research Design and METHODS: Three SNPs known to be associated with CKD (rs4821480, rs5756152 and rs12107) were genotyped using Taqman assay in 716 adults (198 with diabetes) from the Bellville-South community, Cape Town. Glomerular filtration rate was estimated (eGFR) and urinary albumin/creatinine ratio (ACR) assessed. Multivariable regressions were used to relate the SNPs with renal traits. RESULTS: Mean age was 53.6 years, with the expected differences observed in characteristics by diabetic status. Significant associations were found between rs575152 and serum creatinine, and eGFR in the total population, and in diabetic participants (all p≤0.003), but not in non-diabetics (all p≥0.16), with significant interactions by diabetes status (interaction-p≤0.009). The association with ACR was borderline in diabetic participants (p = 0.05) and non-significant in non-diabetics (p = 0.85), with significant interaction (interaction p = 0.02). rs12107 was associated with fasting-, 2-hour glucose and HbA1c in diabetic participants only (interaction-p≤0.003), but not with renal traits. CONCLUSION: MYH9 SNPs were associated with renal traits only in diabetic participants in this population. Our findings and other studies suggest that MYH9 may have a broader genetic risk effect on kidney diseases.
- ItemOpen AccessRisk models to predict hypertension: a systematic review(Public Library of Science, 2013) Echouffo-Tcheugui, Justin B; Batty, G David; Kivimäki, Mika; Kengne, Andre PBACKGROUND: As well as being a risk factor for cardiovascular disease, hypertension is also a health condition in its own right. Risk prediction models may be of value in identifying those individuals at risk of developing hypertension who are likely to benefit most from interventions. Methods and FINDINGS: To synthesize existing evidence on the performance of these models, we searched MEDLINE and EMBASE; examined bibliographies of retrieved articles; contacted experts in the field; and searched our own files. Dual review of identified studies was conducted. Included studies had to report on the development, validation, or impact analysis of a hypertension risk prediction model. For each publication, information was extracted on study design and characteristics, predictors, model discrimination, calibration and reclassification ability, validation and impact analysis. Eleven studies reporting on 15 different hypertension prediction risk models were identified. Age, sex, body mass index, diabetes status, and blood pressure variables were the most common predictor variables included in models. Most risk models had acceptable-to-good discriminatory ability (C-statistic>0.70) in the derivation sample. Calibration was less commonly assessed, but overall acceptable. Two hypertension risk models, the Framingham and Hopkins, have been externally validated, displaying acceptable-to-good discrimination, and C-statistic ranging from 0.71 to 0.81. Lack of individual-level data precluded analyses of the risk models in subgroups. CONCLUSIONS: The discrimination ability of existing hypertension risk prediction tools is acceptable, but the impact of using these tools on prescriptions and outcomes of hypertension prevention is unclear.
- ItemOpen AccessThe CRADLE vital signs alert: qualitative evaluation of a novel device designed for use in pregnancy by healthcare workers in low-resource settings(BioMed Central, 2018-01-05) Nathan, Hannah L; Boene, Helena; Munguambe, Khatia; Sevene, Esperança; Akeju, David; Adetoro, Olalekan O; Charanthimath, Umesh; Bellad, Mrutyunjaya B; de Greeff, Annemarie; Anthony, John; Hall, David R; Steyn, Wilhelm; Vidler, Marianne; von Dadelszen, Peter; Chappell, Lucy C; Sandall, Jane; Shennan, Andrew HBackground: Vital signs measurement can identify pregnant and postpartum women who require urgent treatment or referral. In low-resource settings, healthcare workers have limited access to accurate vital signs measuring devices suitable for their environment and training. The CRADLE Vital Signs Alert (VSA) is a novel device measuring blood pressure and pulse that is accurate in pregnancy and designed for low-resource settings. Its traffic light early warning system alerts healthcare workers to the need for escalation of care for women with hypertension, haemorrhage or sepsis. This study evaluated the usability and acceptability of the CRADLE VSA device. Methods: Evaluation was conducted in community and primary care settings in India, Mozambique and Nigeria and tertiary hospitals in South Africa. Purposeful sampling was used to convene 155 interviews and six focus groups with healthcare workers using the device (n = 205) and pregnant women and their family members (n = 41). Interviews and focus groups were conducted in the local language and audio-recorded, transcribed and translated into English for analysis. Thematic analysis was undertaken using an a priori thematic framework, as well as an inductive approach. Results: Most healthcare workers perceived the CRADLE device to be easy to use and accurate. The traffic lights early warning system was unanimously reported positively, giving healthcare workers confidence with decision-making and a sense of professionalism. However, a minority in South Africa described manual inflation as tiring, particularly when measuring vital signs in obese and hypertensive women (n = 4) and a few South African healthcare workers distrusted the device’s accuracy (n = 7). Unanimously, pregnant women liked the CRADLE device. The traffic light early warning system gave women and their families a better understanding of the importance of vital signs in pregnancy and during the postpartum period. Conclusion: The CRADLE device was well accepted by healthcare workers from a range of countries and levels of facility, including those with no previous vital signs measurement experience. The device motivated women to attend primary care and encouraged them to accept treatment and referral.
- ItemOpen AccessThe relationship between objectively-measured attributes of the built environment and selected cardiovascular risk factors in a South African urban setting(BioMed Central, 2018-07-09) Malambo, Pasmore; De Villiers, Anniza; Lambert, Estelle V; Puoane, Thandi; Kengne, Andre PAbstract Background Evidence concerning the relationship between objectively-measured attributes of the built environment with cardio-metabolic risk in populations from lower- and middle-income countries is lacking. In this paper, we describe the association between the objectively-measured built environment with body mass index, blood pressure and physical activity in adult South Africans. Methods This cross-sectional study included 341 adults aged ≥35 years drawn from the Cape Town arm of the Prospective Urban Rural Epidemiology (PURE) cohort study. All Cape Town PURE participants were invited to take part in the study. Actigraph GT3X accelerometer and Geographic Information Systems were used to measure physical activity and built environment attributes (community center, shopping center and taxi rank). Results In age and sex adjusted models (reference 500 m), access to community centers (1000 m) was positively related to body mass index [beta 4.70 (95%CI: 2.06 to 7.34)] and diastolic blood pressure [4.97 (0.00 to 9.95)]. Distance from a community center (1600 m) was positively related to diastolic blood pressure [6.58 (1.57 to 11.58)] and inversely with moderate-to-vigorous physical activity [− 69.30 (− 134.92 to − 3.70)]. Distance to a shopping center (1600 m) was positively related to body mass index [4.78 (1.11 to 8.45)] and shopping center (1000 m) was positively related to systolic blood pressure respectively [76.99 (0.03 to 83.95)]. Conclusion Distance to community and shopping centers were significantly associated with BMI, systolic, diastolic blood pressure and moderate-to-vigorous physical activity. Future research should include multiple aspects of built environment variables in order to provide for a broader understanding of their effect on cardiovascular risk profile of African populations.