Changes in waist circumference relative to body mass index in Chinese adults, 1993–2009

• Published in: International Journal of Obesity Vol. 38; no. 12; pp. 1503 - 1510
• Main Authors: Stern, D, Smith, L P, Zhang, B, Gordon-Larsen, P, Popkin, B M
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01-12-2014; Nature Publishing Group
• Subjects: 692/699/2743/393; 692/700/478/174; Adult; Adults; Age; Asian Continental Ancestry Group - statistics & numerical data; Biological and medical sciences; Body Fat Distribution; Body Mass Index; Body size; Cardiovascular Diseases - blood; Cardiovascular Diseases - epidemiology; Cardiovascular Diseases - prevention & control; China - epidemiology; Confidence intervals; Cross-Sectional Studies; Diabetes Mellitus, Type 2 - blood; Diabetes Mellitus, Type 2 - epidemiology; Diabetes Mellitus, Type 2 - prevention & control; Epidemiology; Female; Health Promotion and Disease Prevention; Health risks; Households; Humans; Internal Medicine; Life Style; Male; Medical sciences; Medicine; Medicine & Public Health; Men; Metabolic Diseases; Metabolic Syndrome - blood; Metabolic Syndrome - epidemiology; Metabolic Syndrome - prevention & control; Middle Aged; Miscellaneous; Nutrition; Nutrition Surveys; Obesity; Obesity, Abdominal - blood; Obesity, Abdominal - epidemiology; Obesity, Abdominal - prevention & control; original-article; Polls & surveys; Prevalence; Prospective Studies; Public Health; Public health. Hygiene; Public health. Hygiene-occupational medicine; Risk Factors; Statistical analysis; Statistics; Suburban areas; Time Factors; Trends; Waist Circumference; Women; Womens health; Asia; China; United States > US; China, People's Rep; Human; Obesity; Asiatic; Nutrition; Nutrition disorder; Metabolic diseases; Corporal biometry; Change; 2009; Body mass index; Waist circumference; 1993; Adult; Chinese; Nutritional status; Public health
• ISSN: 0307-0565; 1476-5497
• DOI: 10.1038/ijo.2014.74

Background:
Although body mass index (BMI) and waist circumference (WC) are correlated, the relationship between WC and BMI may have changed over time.
Objectives:
 To describe temporal trends in BMI and WC distributions and quantify the increase in WC at a given BMI over time.
Subjects/Methods:
Data on adults aged 20–59 years from two waves (1993 and 2009) of the China Health and Nutrition Survey were used in a pooled cross-sectional analysis. Quantile regression examined age-adjusted temporal trends in the distributions of BMI and WC. Linear regression examined changes in mean WC over time, adjusting for BMI, age at survey and survey year. All models were stratified by gender.
Results:
There was a significant increase in BMI and WC over time, particularly at the 95th quantile: on average, men had 2.8 kg m
−2
(95% confidence interval (CI): 2.4, 3.3) and women 1.5 kg m
−
2
(95% CI: 1.1, 2.0) higher BMI in 2009 compared with their counterparts in 1993. WC increased by 9.0 cm (95% CI: 7.5, 10.1) and 5.0 cm (95% CI: 3.4, 6.6) for men and women, respectively. On average, men and women had a 3.2 cm (95% CI: 2.8, 3.7) and 2.1 cm (95% CI: 1.7, 2.5) higher WC in 2009 compared with their counterparts in 1993, holding BMI and age constant. WC adjusted for BMI increased to a larger extent among obese versus lean individuals and among younger versus older women.
Conclusions:
For both genders, BMI and WC increased significantly over time, with particularly greatest increase in magnitude in the upper tail of the BMI and WC distributions. Furthermore, WC at equivalent BMIs was higher in 2009, compared with their counterparts in 1993. Our findings suggest that even if BMI remained constant from 1993 to 2009, adults in 2009 might be at increased cardiometabolic risk as a result of their higher WC.