Waist-to-height ratio is a useful indicator of cardio-metabolic risk in South Africa.

BACKGROUND: The use of waist-to-height ratio has been suggested as a better proxy indicator of central obesity.

OBJECTIVE: To compare the utility of waist-to-height ratio with commonly used adiposity indices of body mass index, waist circumference and waist-to-hip ratio to identify cardio-metabolic diseases in 25-74-year-old black residents of Cape Town.

METHODS: This cross-sectional study, stratified for age and gender, determined cardio-metabolic abnormalities by administered questionnaires, clinical measurements and biochemical analyses, including oral glucose tolerance tests. Correlations between adiposity indices with cardio-metabolic components were examined. Age- and gender-adjusted logistic regression analyses determined the associations of obesity by these adiposity indices with cardio-metabolic abnormalities.

RESULTS: The study comprised 392 men and 707 women. Compared with other adiposity indices, waist-to-height ratio in men correlated most closely with fasting (0.360) and 2-hour (0.388) glucose levels, total cholesterol (0.267), low-density lipoprotein cholesterol (0.351) and triglycerides (0.400). In women, waist-to-height ratio correlated the best with systolic blood pressure (0.254) and diastolic blood pressure (0.287). Of the adiposity indices, waist circumference was most strongly associated with diabetes (odds ratio 4.27, 95% confidence interval: 2.39-7.62), low high-density lipoprotein cholesterol (2.84, 1.90-4.26) and hypertriglyceridaemia (3.60, 2.03-6.40), whereas raised waist-to-height ratio was most closely related to hypertension (1.61, 1.07-2.42), hypercholesterolaemia (1.72, 1.04-2.83) and raised low-density lipoprotein cholesterol (2.46, 1.70-3.55).

CONCLUSIONS: Compared with other adiposity indices, the better correlation of waist-to-height ratio with many cardio-metabolic components, particularly in men, and the stronger association of raised waist-to-height ratio with hypertension, hypercholesterolaemia and raised low-density lipoprotein cholesterol support the utility of waist-to-height ratio in routine assessments of adiposity in this population, which may improve the identification of cardio-metabolic risk.