Arterial stiffness, ambulatory blood pressure and low-grade albuminuria in non-diabetic African and caucasian men: the SABPA study

Abstract

Recent evidence suggests that low-grade urinary albumin excretion is a marker of early general attenuation of vascular function, but studies are limited to Caucasian population groups. We compared low-grade urinary albumin excretion (<3.5 mg mmol−1 or 30 μg mg−1) between non-diabetic African (aged, 41.7 years; n=70) and Caucasian (aged, 44.6 years; n=91) men and ethnic-specific associations thereof with arterial stiffness and ambulatory blood pressure. The albumin-to-creatinine ratio (ACR) was determined from an 8 h overnight urine collection. We recorded ambulatory blood pressure over 24 h during a typical workday and the carotid–dorsalis pedis pulse wave velocity measured the next morning after a controlled overnight stay. ACR was higher in Africans compared with Caucasians (P<0.001), also after adjusting for 24 h systolic blood pressure, diastolic blood pressure and hypertension prevalence (P<0.001) or when grouped by similar 24 h mean arterial pressures (P<0.01 for all categories). Daytime (P=0.002) and night time (P< 0.001) systolic and daytime (P<0.001) and night time (P<0.001) diastolic blood pressures were higher in Africans compared with Caucasians, but no differences existed for daytime and night time pulse pressure and pulse wave velocity. In African men only, after adjustment for covariates, night time systolic blood pressure (β=0.347; P=0.003), diastolic blood pressure (β=0.298; P=0.010) and mean arterial pressure (β=0.331; P=0.004) correlated positively with ACR. In addition, daytime (β=0.265; P=0.032) and night time (β=0.258; P=0.038) pulse pressure as well as pulse wave velocity (β=0.271; P=0.032) correlated positively with ACR. In conclusion, arterial stiffness and ambulatory blood pressure are already associated with low-grade albuminuria in non-diabetic African men with normal kidney function.