Changes in body composition and cardiometabolic risk among black South African adults

Abstract

Background and objectives: Obesity-related health risk may differ by ethnicity at the same body mass index (BMI). The objectives of this study were too determine the predictive value of the World Health Organization (WHO) overweight cut-point of BMI of 25 kg.m2 in men and women, respectively, to identify 10-year cardiometabolic risk and to determine optimal male (M) and female (F) BMI cut-points to identify 10-year cardiometabolic risk. Methods: In the longitudinal PURE study of healthy black South Africans (n=2010), aged 30-90 years in 2005, demographic, lifestyle and anthropometric measures were taken and blood pressure, fasting serum triglycerides, high-density lipoprotein (HDL)-cholesterol and blood glucose were measured. Three or more risk factors according to international metabolic syndrome (MetS) criteria (fasting plasma glucose >5.6 mmol/L /oral hypoglycemic drugs, systolic blood pressure (SBP) >130 and/or diastolic blood pressure (DBP) >85 /anti-hypertensive drugs, serum TG >1.7 mmol/L, HDL-cholesterol <1 mmol/L M /<1.3 mmol/L F) and waist circumference (WC) above sex-specific cut-points (>94cm M/ >80cm F) in 2015 were defined as elevated cardiometabolic risk. Results: Participants with WC above sex-specific cut-points in 2005 had significantly higher odds of having the MetS in 2015 (odds ratio, OR = 6.99, 95% CI 5.01, 9.75). Participants with BMI in the overweight/obese range (BMI > 25 kg/m2) in 2005 had significantly higher odds of having the MetS in 2015 (OR = 6.38, 95% CI 4.55, 8.94). Receiver Operating Characteristic curves to identify a sex-specific optimal BMI cut-point associated with increased 10-year risk indicated a BMI cut-point of 23.3 kg/m2 in men and 24.6 kg/m2 in women. A BMI cut-point of 30 kg/m2 had poor diagnostic performance. WC cut-points to predict 10-year risk of MetS were 78.0 cm in women and 84.0 cm in men. All cut-points were lower than international proposed cut-points for adiposity. Conclusions: Baseline BMI and WC were significantly associated with increased cardiometabolic risk after follow-up. The predictive value of the WHO overweight cut-point of body mass index (BMI > 25 kg/m2) was similar to the new sex-specific cutpoints (23.3 kg/m2 for men, 24.6 kg/m2 for women), but a BMI of 30 kg/m2 had poor diagnostic ability