title: 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.
  
  
  METHODS
  The study consisted of 101 urbanised African and 101 Caucasian male school teachers. We measured 24h 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 24h, 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, 24h 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.
authors.affiliation: Hypertension in Africa Research Team, School for Physiology, Nutrition, and Consumer Sciences, North-West University, Potchefstroom Campus, Potchefstroom, South Africa.
authors.forename: A J
authors.initials: AJ
authors.lastname: Schultz
authors.forename: A E
authors.initials: AE
authors.lastname: Schutte
authors.forename: R
authors.initials: R
authors.lastname: Schutte
mesh_terms: D000328:Adult; D017954:Africa South of the Sahara / Q000208:ethnology; D000368:Aged; D000886:Anthropometry / Q000379:methods; D044383:Black People / Q000208:ethnology*; D001794:Blood Pressure / Q000502:physiology*; D002318:Cardiovascular Diseases / Q000175:diagnosis* / Q000208:ethnology* / Q000503:physiopathology; D059168:Carotid Intima-Media Thickness; D003430:Cross-Sectional Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D044465:White People / Q000208:ethnology*