The Optimal Ethnic-Specific Waist-Circumference Cut-Off Points of Metabolic Syndrome among Low-Income Rural Uyghur Adults in Far Western China and Implications in Preventive Public Health

Abstract

Background: Metabolic syndrome is pandemic; however, the cut-off values for waist circumference (WC) vary widely depending on the ethnic groups studied and the criteria applied for WC measurement. Previous studies for defining optimal WC cut-off points included high-income and urban settings, and did not cover low-income, rural settings, especially for ethnic minorities. This study aimed at defining optimal ethnic-specific WC cut-off points in a low-income, rural population comprising the largest inhabitant minority group residing in far Western China. Methods: Questionnaire-based surveys, physical examinations, and blood testing of 3542 individuals were conducted in 2010, using a stratified cluster random sampling method in rural Uyghur residents (≥18 years old) from 12 villages in Xinjiang, China, approximately 4407 km away from the capital city, Beijing. Metabolic syndrome was defined according to the International Diabetes Federation (IDF) criteria. Optimal, ethnic-specific WC cut-off values for diagnosing metabolic syndrome were determined using receiver operator characteristic (ROC) curve analysis. Results: As WC increased, there was a significant, increasing trend of detection and risk in rural Uyghur adults, regardless of the presence of ≥1 or ≥2 components of metabolic syndrome by IDF criteria. The optimal ethnic-specific WC cut-off point to predict the presence of metabolic syndrome was 85 cm for men and 82 cm for women. With these cut-off points, the prevalence rates of metabolic syndrome among men, women, and overall population in Uyghur adults were 19.5%, 23.0%, and 21.3%, respectively. Conclusions: We report a high prevalence of metabolic syndrome, especially in women, among rural Uyghurs in Western China. A WC cut-off of 85 cm in men and 82 cm in women was the best predictor of metabolic syndrome in this population. Because of the cost-effectiveness in measuring WC, we recommend that these WC cut-off points be integrated into local preventive policies for public health as the primary screening criteria for metabolic syndrome and related diseases among low-income, rural minorities.

Keywords: Uyghur; cut-off points of waist circumference; ethnic-specific; low-income rural setting; metabolic syndrome; public health.

Figure 1

Receiver operator characteristic (ROC) curves for waist circumference (WC) to predict the presence of at least two other components of the metabolic syndrome, as defined by the IDF, in men and women. Area under the ROC curve: 0.636 in men and 0.658 in women. WC cut-off point: 85 cm in men (sensitivity 60.0%, specificity 59.3%) and 82 cm in women (sensitivity 67.0%, specificity 57.3%).

Figure 2

Prevalence rates of metabolic syndrome in rural Uyghur adult using the ethnic-specific and traditional waist circumference (WC) cut-off values by IDF criteria. Ethnic-specific WC cut-off values: WC ≥ 85 cm for men, and ≥82 cm for women; traditional WC cut-off values: WC ≥ 90 cm for men, and ≥80 cm for women.