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Double product and end-organ damage in African and Caucasian men: The SABPA study

  • A.J. Schultz
    Affiliations
    Hypertension in Africa Research Team (HART), School for Physiology, Nutrition, and Consumer Sciences, North-West University (Potchefstroom Campus), Potchefstroom, South Africa
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  • A.E. Schutte
    Affiliations
    Hypertension in Africa Research Team (HART), School for Physiology, Nutrition, and Consumer Sciences, North-West University (Potchefstroom Campus), Potchefstroom, South Africa
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  • R. Schutte
    Correspondence
    Corresponding author at: Hypertension in Africa Research Team (HART), Private Bag x6001, North-West University (Potchefstroom Campus), Potchefstroom, 2520, South Africa. Tel.: +27 18 299 2435; fax: +27 18 299 2433.
    Affiliations
    Hypertension in Africa Research Team (HART), School for Physiology, Nutrition, and Consumer Sciences, North-West University (Potchefstroom Campus), Potchefstroom, South Africa
    Search for articles by this author

      Abstract

      Background

      Increasing urbanisation in sub-Saharan African countries is causing a rapid increase in cardiovascular disease. Evidence suggests that Africans have higher blood pressures and a higher prevalence of hypertension-related cardiovascular morbidity and mortality, compared to Caucasians. We investigated double product (systolic blood pressure×heart rate), a substantial measure of cardiac workload, as a possible cardiovascular risk factor in African and Caucasian men.

      Material and methods

      The study consisted of 101 urbanised African and 101 Caucasian male school teachers. We measured 24 h ambulatory blood pressure and the carotid cross-sectional wall area, and determined left ventricular hypertrophy electrocardiographically by means of the Cornell product. Urinary albumin and creatinine were analysed to obtain the albumin-to-creatinine ratio.

      Results

      Africans had higher 24 h, daytime and nighttime systolic- and diastolic blood pressure, heart rate and resultant double product compared to the Caucasians. In addition, markers of end-organ damage, albumin-to-creatinine ratio and left ventricular hypertrophy were higher in the Africans while cross-sectional wall area did not differ. In Africans after single partial and multiple regression analysis, 24 h systolic blood pressure, but not double product or heart rate, correlated positively with markers of end-organ damage (cross-sectional wall area: β=0.398, P=0.005; left ventricular hypertrophy: β=0.455, P<0.001; albumin-to-creatinine ratio: β=0.280, P=0.012). No associations were evident in Caucasian men.

      Conclusions

      Double product may not be a good marker of increased cardiovascular risk when compared to systolic blood pressure in African and Caucasian men.

      Keywords

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