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Open Access Research article

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

Thomas A Gaziano113*, Ankur Pandya2, Krisela Steyn133, Naomi Levitt133, Willie Mollentze4, Gina Joubert5, Corinna M Walsh6, Ayesha A Motala7, Annamarie Kruger8, Aletta E Schutte9, Datshana P Naidoo10, Dorcas R Prakaschandra11 and Ria Laubscher12

Author Affiliations

1 Divisions of Cardiovascular Medicine, Brigham and Women’s Hospital, 75 Francis Street, Boston, MA 02115, USA

2 Department of Public Health, Division of Health Policy, Weill Cornell Medical College, 402 E. 67th Street, New York, NY 10065, USA

3 Department of Medicine, University of Cape Town, Observatory, Cape Town 7925, South Africa

4 Department of Internal Medicine, School of Medicine, University of the Free State, 205 Nelson Mandela Drive, Park West, Bloemfontein 9301, South Africa

5 Department of Biostatistics, University of the Free State, 205 Nelson Mandela Drive, Park West, Bloemfontein 9301, South Africa

6 School of Tourism, Hospitality and Sport, Technikon Free State, 20 President Boshof Street, Bloemfontein 9320, South Africa

7 Department of Endocrinology, Nelson R. Mandela School of Medicine, University of KwaZulu-Natal, Mazisi Kunene Road, Durban 4041, South Africa

8 Faculty of Health Sciences-Africa Unit for Transdisciplinary Health Research, North-West University, Hofman Street, Potchefstroom 2531, South Africa

9 Hypertension in Africa Research Team, North-West University, Potchefstroom 2531, South Africa

10 Department of Cardiology, University of KwaZulu-Natal, Inkosi Albert Luthuli Central Hospital, Bellair Road, Durban 4041, South Africa

11 Department of Biomedical and Clinical Technology, Durban University of Technology, University of KwaZulu-Natal, Mazisi Kunene Road, Durban 4041, South Africa

12 Biostatistics Unit, Medical Research Council, Francie van Zijl Drive, Tygerberg 7505, South Africa

13 Chronic Diseases Initiative for Africa, Department of Medicine, University of Cape Town, Observatory, Cape Town 7925, South Africa

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BMC Medicine 2013, 11:170  doi:10.1186/1741-7015-11-170

Published: 24 July 2013

Abstract

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.

Keywords:
Cardiovascular disease; Prevention; Cholesterol; Stroke; Coronary heart disease