A comparison of uric acid levels in Black African vs Caucasian women from South Africa: the POWIRS study.

OBJECTIVES: Elevated levels of uric acid are often associated with cardiometabolic risk factors. The aim of this study was to determine whether uric acid levels differ between African and Caucasian women and whether uric acid is associated with cardiometabolic risk factors within the two ethnic groups. METHODS: Women from African (N=102) and Caucasian (N=115) descent were recruited and their uric acid levels measured. Anthropometric measurements included height (stature), weight, and waist circumference. Correlations between uric acid and cardiometabolic variables within each ethnic group were also determined. RESULTS: African women had significantly lower levels of uric acid (P<.01) and significantly higher levels of blood pressure (P=.05) compared to the Caucasian women. There was a significant increase in blood pressure from the lower to higher uric acid tertiles in the African women. Uric acid strongly correlated with waist circumference in both ethnic groups. CONCLUSIONS: Despite their higher blood pressure, the African women had lower uric acid levels, yet they showed a significant increase in blood pressure from a low uric acid tertile to high uric acid tertile, which was not noticeable in the Caucasian women. A possible explanation is a lower waist circumference in African women compared to Caucasian women.

Uric acid and the cardiovascular profile of African and Caucasian men.

The African population is considered a high-risk group for the development of hypertension, and identifying risk factors are therefore essential in preventive actions against cardiovascular disease (CVD). Elevated levels of uric acid (UA) are often associated with CVD. Our first aim was to establish possible ethnic differences in UA levels between African and Caucasian men. Our second aim was to determine any associations between UA levels and cardio-metabolic variables, and also how these correlates differ between the two groups. African (N=87) and Caucasian (N=121) men participated in this cross-sectional study. Our results have shown that African men had significantly lower (353±87.7 vs 401±98.2; P<0.01) UA levels compared with Caucasian men. Waist circumference and triglycerides correlated strongly with UA in both ethnic groups. This was confirmed with a forward stepwise multiple regression analysis. After adjustment for confounders, the correlation between UA and triglycerides remained significant only in the Caucasians (r=0.29; P=0.02), whereas only the African men showed an independent correlation between UA and total peripheral resistance (TPR) (r=0.23; P=0.04). TPR increased significantly across UA tertiles only in the African men (P=0.01 vs P=0.96). In conclusion, despite their lower UA levels, Africans showed an independent relationship between UA and vascular resistance, indicating a possible explanation for their high prevalence of hypertension.

Ethnic and gender differences regarding the insulin-blood pressure relationship.

Ageing is associated with increased insulin and C-peptide levels. Due to a lack of data, our first aim was to establish whether this also holds true for Africans from South Africa. Our second aim was to determine whether an association between insulin/C-peptide levels and blood pressure exist within an African and Caucasian population with increasing age, as well as to establish gender differences. African men and women (N=260) and Caucasian men and women (N=369) were recruited and stratified into age groups (18-35 years, 36-45 years and >45 years). ANCOVAs and partial correlations were performed. Results showed opposing changes in insulin/C-peptide levels of African and Caucasian men with increasing age. Insulin/C-peptide tended to decrease in African men, whereas insulin tended to increase and C-peptide increased significantly (p=0.03) in Caucasian men. Despite similar obesity levels, the oldest African women had significantly lower insulin (p<0.01) and C-peptide (p<0.01) levels compared to their Caucasian counterparts. In conclusion, insulin/C-peptide levels tended to decrease in the African population with increasing age. Despite significantly lower levels of insulin, blood pressure levels of African men seems to be affected more detrimentally compared to their Caucasian counterparts, leaving them more vulnerable for the development of cardiovascular diseases.