Waist circumference cut-off points for identification of abdominal obesity among the tunisian adult population.

AIMS: Waist circumference (WC) is a convenient measure of abdominal adipose tissue. It itself is a cardiovascular disease (CVD) and diabetes-risk factor and is strongly linked to other CVD risk factors. There are, however, ethnic differences in the relationship of WC to the other risk factors. The aim of this study was to determine the optimal cut-off points of WC and body mass index (BMI) at which cardiovascular risk factors can be identified with maximum sensitivity and specificity in a representative sample of the Tunisian adult population and to investigate any correlation between WC and BMI. METHODS: We used a sample of the Tunisian National Nutrition Survey, a cross-sectional population-based survey, conducted in 1996 on a large nationally representative sample, which included 3435 adults (1244 men and 2191 women) of 20 years or older. WC, BMI, blood pressure and fasting blood measurements (plasma glucose, total cholesterol, triglycerides) were recorded. Receiver operating characteristic (ROC) curve analysis was used to identify optimal cut-off values of WC and BMI to identify with maximum sensitivity and specificity the detection of high blood pressure, hyperglycaemia, high blood cholesterol and hypertriglyceridaemia. RESULTS: ROC curve analysis suggested WC cut-off points of 85 cm in men and 85 cm in women for the optimum detection of high blood pressure, diabetes and dyslipidaemia. The optimum BMI cut-off points for predicting cardiovascular risk factors were 24 kg/m(2) in men and 27 kg/m(2) in women. The cut-off points recommended for the Caucasian population differ from those appropriate for the Tunisian population. The data show a continuous increase in odds ratios of each cardiovascular risk factor, with increasing level of WC and BMI. WC exceeding 85 cm in men and 79 cm in women correctly identified subjects with a BMI of >/=25 kg/m(2), sensitivity of >90% and specificity of >83%. CONCLUSIONS: Based on the ROC analysis, we suggest a WC of 85 cm for both men and women as appropriate cut-off points to identify central obesity for the purposes of CVD and diabetes-risk detection among Tunisians. WCs of 85 cm in men and 79 cm in women were the most sensitive and specific to identify most subjects with a BMI >/=25 kg/m(2).

Prevalence of metabolic abnormalities in the Tunisian adults: a population based study.

AIMS: To estimate the prevalence of individual metabolic abnormalities and the cluster of metabolic abnormalities in a representative sample of the Tunisian adult population and to identify their relationship with gender, age and residency. The definition used is an adaptation of the NCEP ATP III definition, using total cholesterol>or=5.2 mmol/l instead of HDL-cholesterol. MATERIALS AND METHODS: We used a sample of the Tunisian National Nutrition Survey (TNNS), a cross-sectional health survey conducted in 1996, to estimate the nutritional status of the population. The TNNS included 2 927 adults aged 20 years or older who had measurements of height, body weight, waist circumference, blood pressure, fasting plasma glucose, total cholesterol and triglycerides. The cluster of metabolic abnormalities was defined as the presence of three or more metabolic abnormalities. RESULTS: The prevalence of abdominal obesity, hypertriglyceridemia, high total cholesterol, high blood pressure and high fasting plasma glucose was, respectively, 9%, 23%, 24%, 45% and 15% in men and 33%, 19%, 29%, 44% and 15% in women. The prevalence of the cluster was more frequent in women than in men (18% versus 13%, P<0.001) and in those living in urban communities (21% in women, 16% in men) rather than rural communities (11% in women, 8% in men) (P<0.001). The prevalence also increased significantly with age (P<0.001). CONCLUSION: The cluster of metabolic abnormalities and its components are common in the Tunisian adult population and prevalence increases significantly with female sex, urban residency and age.