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

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, albuminto- 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, Pb0.001; albuminto- 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.