Optimal waist-to-height ratio values for cardiometabolic risk screening in an ethnically diverse sample of South African urban and rural school boys and girls

BACKGROUND: 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

Chronic kidney diseases in mixed ancestry South African populations : prevalence, determinants and concordance between kidney function estimators

Publication of this article was funded by the Stellenbosch University Open Access Fund.The original publication is available at http://www.biomedcentral.com/bmcnephrolBackground: Population-based data on the burden of chronic kidney disease (CKD) in sub-Saharan Africa is still very limited. We assessed the prevalence and determinants of CKD, and evaluated the concordance of commonly advocated estimators of glomerular filtration rate (eGFR) in a mixed ancestry population from South Africa. Methods: Participants were a population-based sample of adults selected from the Bellville-South community in the metropolitan city of Cape Town. eGFR was based on the Cockroft-Gault (CG), Modification of Diet in Kidney Disease (MDRD) and CKD Epidemiology Collaboration (CKD-EPI) equations (with and without adjustment for ethnicity). Kidney function staging used the Kidney Disease Outcome Quality Initiative (KDOQI) classification. Logistic regressions and kappa statistic were used to investigate determinants of CKD and assess the agreement between different estimators. Results: The crude prevalence of CKD stage 3–5 was 14.8% for Cockcroft-Gault, 7.6% and 23.9% respectively for the MDRD with and without ethnicity correction, and 7.4% and 17.3% for the CKD-EPI equations with and without ethnicity correction. The highest agreement between GFR estimators was between MDRD and CKD-EPI equations, both with ethnicity correction, Kappa 0.91 (95% CI: 0.86-0.95), correlation coefficient 0.95 (95% CI: 0.94-0.96). In multivariable logistic regression models, sex, age and known hypertension were consistently associated with CKD stage 3–5 across the 5 estimators Conclusions: The prevalence of CKD stages greater than 3 is the highest reported in Africa. This study provides evidence for support of the CKD-EPI equation for eGFR reporting and CKD classification.Stellenbosch University Open Access FundPublishers' versio

HbA1c of 6.5% to diagnose Diabetes Mellitus—Does it work for Us?—The Bellville South Africa study

The original publication is available at http:/www.plosone.orgBibliographyBackground: HbA1c has been the gold standard for glycaemic control follow-up for decades. In 2009, a level of 6.5% (48 mmol/mol) was proposed as diagnostic for diabetes. We test this cut-off in our community. Methods: Participants (946) from a community-based study were screened for diabetes using either a fasting blood glucose or oral glucose tolerance test (OFTT). The HbA1c cut-off of 6.5% was tested for each group. A receiver operator characteristic (ROC) curve for both groups was generated to establish an optimal cut-off. Results: Our study included 224 (23.7%) males and 722 (76.3%) females. Using fasting blood glucose alone, 117 (14%) were diagnosed with diabetes 250% had an HbA1c value of $6.5with diabetes 246$6.5% (48 mmol/mol). ROC curves found a level of 6.1% (43 mmol/mol) to be optimal in both groups (AUC 0.85 and 0.82 respectively). The sensitivities were 80% and 75% and the specificities 77% and 78% respectively. Conclusions: A cut off of 6.5% (48 mmol/mol) is a good diagnostic tool with its high specificity; however the low sensitivity limits its use. We found a level of 6.1% (43 mmol/mol) to be optimal. This emphasizes the need for evidenced based values to be established in various population groups.National Health Laboratory Services of South AfricaUniversity Research Fund of the Cape Peninsula University of TechnologyPublishers' Versio

Distribution and association of hs-CRP with cardiovascular risk variables of metabolic syndrome in adolescent learners

CITATION: Rensburg, M. A., et al. 2012. Distribution and association of hs-CRP with cardiovascular risk variables of metabolic syndrome in adolescent learners. African Journal of Laboratory Medicine, 1(1): 1-6, doi: 10.4102/ajlm.v1i1.10.The original publication is available at http://www.ajlmonline.orgObjective: Metabolic syndrome (MetS) and its associated cardiovascular risk are on the increase in children. High-sensitivity C-reactive protein (hs-CRP) has emerged as a useful marker for inflammation associated with atherosclerosis and cardiovascular disease. Our aim was to determine the distribution of hs-CRP in an effort to identify the MetS variable that is critical in modulating plasma CRP levels in a population of South African adolescents. Design: A cross-sectional analytical study design was used for this investigation, where the dependent and independent variables were measured simultaneously. Methods: Anthropometric variables, blood pressure, fasting blood glucose and lipids were performed on 324 consenting learners aged 15–18 years from three different ethnic groups (Black, White and Coloured). The National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III) for ages 15–18 year olds was used to define MetS. Results: The prevalence of MetS and obesity was 3.7% and 7.1%, respectively. The hs-CRP levels were significantly higher in subjects with a waist-circumference greater than the 90th percentile (p < 0.01) and in obese learners with MetS, but was lower in adolescents with normal weight and MetS. Median hs-CRP levels increased with an increasing number of metabolic abnormalities and exceeded 3 mg/L in 19% of adolescents. Gender and ethnic differences were observed. Conclusion: Our findings suggest that obesity and waist circumference appear to be major mediators of hs-CRP levels in South African adolescents.http://www.ajlmonline.org/index.php/ajlm/article/view/10Publisher's versio

Chronic kidney diseases in mixed ancestry South African populations : prevalence, determinants and concordance between kidney function estimators

The original publication is available at http://www.biomedcentral.com/1471-2369/14/75Bibliography.ABSTRACT: Population-based data on the burden of chronic kidney disease (CKD) in sub-Saharan Africa is still very limited. We assessed the prevalence and determinants of CKD, and evaluated the concordance of commonly advocated estimators of glomerular filtration rate (eGFR) in a mixed ancestry population from South Africa. Methods Participants were a population-based sample of adults selected from the Bellville-South community in the metropolitan city of Cape Town. eGFR was based on the Cockroft-Gault (CG), Modification of Diet in Kidney Disease (MDRD) and CKD Epidemiology Collaboration (CKD-EPI) equations (with and without adjustment for ethnicity). Kidney function staging used the Kidney Disease Outcome Quality Initiative (KDOQI) classification. Logistic regressions and kappa statistic were used to investigate determinants of CKD and assess the agreement between different estimators. Results The crude prevalence of CKD stage 3–5 was 14.8% for Cockcroft-Gault, 7.6% and 23.9% respectively for the MDRD with and without ethnicity correction, and 7.4% and 17.3% for the CKD-EPI equations with and without ethnicity correction. The highest agreement between GFR estimators was between MDRD and CKD-EPI equations, both with ethnicity correction, Kappa 0.91 (95% CI: 0.86-0.95), correlation coefficient 0.95 (95% CI: 0.94-0.96). In multivariable logistic regression models, sex, age and known hypertension were consistently associated with CKD stage 3–5 across the 5 estimators. Conclusions The prevalence of CKD stages greater than 3 is the highest reported in Africa. This study provides evidence for support of the CKD-EPI equation for eGFR reporting and CKD classification.Publishers' Versio

Stratification of diabetic and normal subjects according to HbA1c cut-off of 6.5% and 6.1%.

<p>Stratification of diabetic and normal subjects according to HbA1c cut-off of 6.5% and 6.1%.</p

ROC curves depicting an HbA1c cut-off value of 6.1% as optimal for the diagnosis of DM according to fasting blood glucose and the OGTT.

<p>Figure 1a area under curve = 0.85, sensitivity = 80%, and specificity = 77%. Figure 1b area under curve = 0.82, sensitivity = 75%, and specificity = 78%.</p

Characteristics of all participants (946), stratified by gender.

<p>FBG, fasting blood glucose; PostBG, post 2-hour blood glucose;</p

Plasma non-esterified fatty acids in patients with multiple sclerosis

Objective: The purpose of this study was to investigate the levels of non-esterified fatty acids in plasma from patients with multiple sclerosis and further to correlate these findings with the neurological profile as measured by the Kurtzke Expanded Disability Status Scale. Methods: Plasma non-esterified fatty acids and esterified fatty acids from 30 control subjects and 31 patients with multiple sclerosis were measured by gas chromatography. Results: Non-esterified fatty acids C18:2n-6, C20:4n-6, C16:1n-7, C18:1n-7, C18:1n-9, C14:0, C16:0 and C18:0 were significantly increased in plasma from patients with multiple sclerosis, P ≤ 0.01, while esterified ed fatty acid C18:2n-6 was decreased, P = 0.003. Fatty acid PC C16:1n-7 and non-esterified fatty acids C16:1n-7, C18:1n-7 and C18:1n-9 showed positive and fatty acids C18:1n-9, C20:0, C22:0 and C24:0 showed inverse correlations with the Functional System Scores. Conclusions: We have identified increased monounsaturated non-esterified fatty acids in plasma from patients with multiple sclerosis as indicative of a worse disease outcome. Further, the decrease in fatty acid C18:2n-6, with increases in non-esterified fatty acids C18:2n-6 and C20:4n-6, suggested a role for these eicosanoid precursor fatty acids in the inflammatory condition experienced by these patients.University Research Fund of the Cape Peninsula University of Technology, South Africa