Repository logo
 

Faculty of Health Sciences

Permanent URI for this communityhttp://ir-dev.dut.ac.za/handle/10321/11

Browse

Has files: YesSubject: search.filters.subject.Coronary heart disease

Search Results

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Comparative assessment of absolute cardiovascular disease risk characterization from non-laboratory- based risk assessment in South African populations
    (BioMed Central, 2013-07-24) Gaziano, Thomas A.; Pandya, Ankur; Steyn, Krisela; Levitt, Naomi; Mollentze, Willie; Joubert, Gina; Walsh, Corinna M; Motala, Ayesha A.; Kruger, Annamarie; Schutte, Aletta E.; Naidoo, Datshana Prakash; Prakaschandra, Dorcas Rosaley; Laubscher, Ria
    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.
  • Thumbnail Image
    Item
    The predictive value of pro brain natriuretic peptide (ProBNP) levels to determine the presence and severity of coronary artery disease in patients with a positive or inconclusive exercise stress test
    (2010) Naidoo, Nivashni; Adam, Jamila Khatoon; Pearce, Adrian
    Cardiovascular disease (CVD) is one of the major causes of premature deaths worldwide. In South Africa, approximately 195 people die from cardiovascular diseases each day. The earlier coronary artery disease (CAD) is detected, the better the prognosis. NT- pro- brain natriuretic peptide (NT-proBNP) is a cardiac neurohormone that is secreted in the cardiac ventricles in response to excessive stretching of heart muscle cells. Brain natriuretic peptide (BNP) is currently being used as a marker of left ventricular dysfunction but limitations are evident in patients with sepsis, volume overload, stroke and acute mitral regurgitation. OBJECTIVES: The main objective of this study was to identify a possible value of NT- proBNP level which indicates CAD. It also aimed to compare NT- proBNP levels with the number of diseased vessels; to assess the association between proBNP levels and patients’ age and gender; to determine the percentage of false positive proBNP levels; to determine the probability of false positive exercise stress testing and to correlate NT- proBNP levels with LVEDP. METHODS: Sixty patients were recruited from the Cardiology Department at St Anne’s hospital to participate in this trial. They were divided into two groups; Group A, the control group, consisted of thirty patients with a positive EST and Group B, the experimental group, consisted of thirty patients with an inconclusive EST. After the EST, all patients from both groups were required to have a NT- proBNP blood test, a left and right coronary angiogram and a left ventriculogram. iii RESULTS: Results of the study showed that post EST NT- proBNP levels, in both groups, increased in the presence of CAD (p<0.001). For the positive EST group, the area under the ROC curve was 0.975 which was highly statistically significantly different from the null hypothesis value of 0.5 (p<0.001) and a cut- off value of 120 pg/ml was identified with the highest sensitivity (95.7%) and specificity (100%). For patients in the inconclusive EST group, the area under the ROC curve was 0.912 which was highly statistically significantly different from the null hypothesis value of 0.5 (p<0.001) and a cut-off value of 85 pg/ml was identified with the highest sensitivity (87.5%) and specificity (86.4%). There was a statistically significant difference between the median NT- proBNP values of males and females in the group of patients with positive EST (p=0.048). The values were higher in males. However, there was no significant difference between the genders in the group with an inconclusive EST. A strong and significant correlation (p<0.001) between left ventricular end diastolic pressures (LVEDP) and number of disease vessels was demonstrated. The probability of a false positive result for EST was 24.1%. and the probability of a false negative result was 25.8%. CONCLUSION: Results of the study showed that post EST NT- proBNP levels, in both groups, increased in the presence of CAD and could accurately predict the presence of CAD. Cut- off values of 120 pg/ml for the positive EST group and 85 pg/ml for the inconclusive EST group were identified with the highest sensitivity and specificity. In the positive EST group, a trend of increasing NT-proBNP with age was and NT-proBNP values were higher in males. The positive EST was relatively accurate at predicting CAD; however, 75.9% of patients with an inconclusive EST did not have CAD.Exercise stress testing in this regard, is therefore relatively inaccurate at predicting CAD in patients with inconclusive ESTs, and the need for an additional tool, such as NT-proBNP measurements post inconclusive EST is warranted in the determination of the presence of CAD.