Comparative assessment of absolute cardiovascular disease risk characterization from non-laboratory-based risk assessment in South African populations.

BACKGROUND: All rigorous primary cardiovascular disease (CVD) prevention guidelines recommend absolute CVD risk scores to identify high- and low-risk patients, but laboratory testing can be impractical in low- and middle-income countries. The purpose of this study was to compare the ranking performance of a simple, non-laboratory-based risk score to laboratory-based scores in various South African populations. METHODS: We calculated and compared 10-year CVD (or coronary heart disease (CHD)) risk for 14,772 adults from thirteen cross-sectional South African populations (data collected from 1987 to 2009). Risk characterization performance for the non-laboratory-based score was assessed by comparing rankings of risk with six laboratory-based scores (three versions of Framingham risk, SCORE for high- and low-risk countries, and CUORE) using Spearman rank correlation and percent of population equivalently characterized as 'high' or 'low' risk. Total 10-year non-laboratory-based risk of CVD death was also calculated for a representative cross-section from the 1998 South African Demographic Health Survey (DHS, n = 9,379) to estimate the national burden of CVD mortality risk. RESULTS: Spearman correlation coefficients for the non-laboratory-based score with the laboratory-based scores ranged from 0.88 to 0.986. Using conventional thresholds for CVD risk (10% to 20% 10-year CVD risk), 90% to 92% of men and 94% to 97% of women were equivalently characterized as 'high' or 'low' risk using the non-laboratory-based and Framingham (2008) CVD risk score. These results were robust across the six risk scores evaluated and the thirteen cross-sectional datasets, with few exceptions (lower agreement between the non-laboratory-based and Framingham (1991) CHD risk scores). Approximately 18% of adults in the DHS population were characterized as 'high CVD risk' (10-year CVD death risk >20%) using the non-laboratory-based score. CONCLUSIONS: We found a high level of correlation between a simple, non-laboratory-based CVD risk score and commonly-used laboratory-based risk scores. The burden of CVD mortality risk was high for men and women in South Africa. The policy and clinical implications are that fast, low-cost screening tools can lead to similar risk assessment results compared to time- and resource-intensive approaches. Until setting-specific cohort studies can derive and validate country-specific risk scores, non-laboratory-based CVD risk assessment could be an effective and efficient primary CVD screening approach in South Africa.

Association of cardio-metabolic risk factors with elevated basal heart rate in South African Asian Indians.

BACKGROUND: The aim of this study was to determine the association of increasing basal heart rate (BHR) with cardio-metabolic risk in a community sample of Asian Indians from South Africa, due to lack of population-based data on the interaction between heart rate and cardiovascular factors. METHODS: Data drawn from 1349 randomly selected participants was collected using the WHO STEPS questionnaire. Anthropometry, blood pressure, physical examination and laboratory analyses of venous blood samples and definition of cardiometabolic derangements were performed according to established guidelines. BHR classified into three categories, i.e., <60 bpm; 60-89 bpm and ≥90 bpm. Stepwise backward regression models were constructed for determination of association between increasing BHR and cardiometabolic parameters. A ROC was constructed to determine the AUC and to determine their sensitivity and specificity for discriminating increasing BHR levels. RESULTS: In 379 men (mean age 42±15 years; mean HR 79±13 bpm) and 970 women (mean age 46±12 years; mean HR 87±7.8 bpm), with BHR significantly higher in women (P<0.0001). The distribution of HR was: <60 bpm (2.7%); HR 60-89 bmp (75.8%); HR≥90 bpm (20.1%). In the adjusted logistic regression model fasting plasma glucose (P=0.02; OR 95% CI: 1.18 [1.02-1.4]); age (P=0.01 OR 95% CI: 0.97 [0.96-0.99]); systolic blood pressure (P<0.001 OR 95% CI: 0.95 [0.9-0.97]), and diastolic blood pressure (P≤0.001 OR 95% CI: 1.1 [1.06-1.1]) emerged as independently associated with increasing BHR. The highest AUC for discriminating increasing BHR was for mean diastolic blood pressure (AUC=0.618; P<0.001), and fasting blood glucose (AUC=0.595; P<0.0001). CONCLUSIONS: Increasing BHR was independently associated with derangements in fasting blood glucose and blood pressure.

The association of cardiometabolic disorders with sleep duration: a cross-sectional study.

Background: Alterations in sleep duration and quality are linked to the development of cardiovascular risk factors and the metabolic syndrome (MetS). The aim of this study was to determine a sex stratified analysis on the role and associations of sleep duration on cardiometabolic risk factors, and the MetS. Methods: Data from 1375 randomly selected participants (15-64 years) was collected for demographic, anthropometric, blood pressure and biochemistry data after overnight fasting, and derangements diagnosed according to published guidelines. Analysis of association between the MetS (harmonised criteria modified for South Asians), sleep duration (self-reported for a 24-hour period), and cardiometabolic risk factors was done using stepwise logistic regression. Results: The BMI, waist circumference (WC), systolic blood pressure (SBP) and diastolic blood pressure (DBP), fasting plasma glucose, total cholesterol, low density lipoprotein were higher (p< 0.05) in subjects who slept <6 hours, with lower HDL. Under 6 hours of sleep was independently associated with raised FPG in men (OR 1.71 95% CI [1.53,5.52]) only. More than 10 hours of sleep was independently associated with increased triglyceride levels in men (1.72[0.56, 5.23]) and women (2.25[1.93,5.42]). Conclusion: The individual components of the Mets, particularly, increased triglycerides and blood glucose are associated with sleep deprivation or excess.