| Objective:Obesity among children and adolescents continues to be a major focus of public health problems in both developed and developing countries. It is well demonstrated that obesity during childhood and adolescents is a risk factor for obesity during adulthood and its related chronic diseases, such as diabetes mellitus, hypertension, cardiovascular disease and some kind of cancer. In order to investigate the current prevalence of obesity among Chinese children and adolescents in 2011, and the trends in obesity from 1991 through 2011.Methods:1 Data were obtained from the China Health and Nutrition Survey(CHNS). We included 2,251 participants(male, 1,178; females, 1,073) aged 2-18 years from CHNS 2011 compared with 21,364 children from the CHNS 1991-2009. Information on age, gender, urban–rural status, height, weight and BMI were collected.2 Overweight and obesity in children aged 2–6 years old was defined using Z-Score curves were generated for males and females. For children aged 7–18 years, the sex- and age-specific BMI cutoff points recommended by World Health Organization(WHO) were used to define “obesity”(overweight and obesity combined). Estimates of the age-adjusted prevalence of overweight and obesity according to the WHO and WGOC recommendations, and annualized odds ratio(AOR) in children and adolescents. Logistic regression was utilized to further assess the changes in obesity throughout the eight waves of the CHNS.3 In addition, comparisons of the prevalence of obesity estimates between the Chinese and National Health and Nutrition Examination Survey(NHANES) in 2011 were conducted. The odds risk(OR) was utilized to assess comparisons of obesity between Americans and Chinese.Results:1 The age-adjusted prevalence of obesity and overweight was 3.35%(95% confidence interval(CI), 2.08%-4.61%) and 6.05%(95% CI, 4.37%-7.73%) among children and adolescents aged 2-6 years by WHO standard in 2011 survey. The prevalence of obesity was 3.76% and 2.85% among males and females, and the prevalence of overweight was 7.04% and 4.84% among males and females. The age-adjusted prevalence of obesity and overweight was 5.99%(95% CI, 4.78%-7.20%) and 15.6%(95% CI, 13.7%-17.4%) among children and adolescents aged 7-18 years by WHO standard. The prevalence of obesity and overweight was 7.27% and 19.6% among males, and 4.64% and 11.3% among females.2 The age-adjusted prevalence of obesity and overweight was 7.41%(95% CI, 6.07%-8.75%) and 18.0%(95% CI, 16.1%-20.0%) among children and adolescents aged 7-18 years by WGOC standard. The prevalence of obesity and overweight was 8.30% and 22.3% among males, and 6.46% and 13.5% among females.3 the prevalence increased from 1.63% in 1991 to 5.99% in 2011 among Chinese adolescents aged 7 through 18 years. Meanwhile, in males the prevalence of obesity increased from 2.36% to 7.27% compared to an increase from 1.40% to 4.64% among females during the eight survey rounds. The increments in the prevalence of obesity in males were greater than in females. In general, a relatively higher overall prevalence increased progressively from 1.85% in 1991 to 7.41% in 2011 using WGOC reference standards. Notably, the prevalence increase from 1.87% to 8.30% among males, and increase from 1.81% to 6.46% among females.4 Additionally, the results of statistical tests for trends in obesity across the eight CHNS from 1991 through 2011 are expressed as AORs. There were significant increases in the overall(AOR, 1.07; CI, 1.06-1.09; and AOR, 1.08; CI, 1.06-1.09) according to the WHO and WGOC criteria, respectively. After stratification by gender, increasing trends in the prevalence of obesity were still observed in males and females. The trends in estimated increases were similar under the combined cut-off point for obesity and overweight.5 In 2011, the medium of BMI in males was higher than that in females at 6 years, 12 years and 18 years examined. Moreover, the highest increase in the BMI was among male adolescents aged 12 years, among whom the medium of BMI increased from 16.3 kg/m2 to 19.6 kg/m2. The medium of BMI increased from 16.3 kg/m2 to 17.5 kg/m2 among female adolescents aged 12 years, but not in other year group.6 In the 2011 survey, the age-adjusted prevalence of obesity among the Chinese was lower than that among Americans(overall, 6.00% vs. 16.4%; males, 6.96% vs. 17.1%; females, 4.94% vs. 15.6%). The estimates of both the age-adjusted obesity prevalence and the combined age-adjusted prevalence of overweight and obesity among the Chinese were significantly lower than the corresponding estimates for Americans.Conclusions:1 The prevalence of obesity and overweight among both males and females aged 2-18 years increased significantly from 1991 through 2011. The increase in the prevalence of obesity and overweight in males was greater than that in females.2 Mean BMI increased slightly across 8 study periods among Chinese children and adolescents aged 2-18 years from 1991 through 2011. Meanwhile, the increases in BMI were most obviously found among males and females in the adolescent.3 In the 2011 survey, the age-adjusted prevalence of obesity and overweight among the Chinese and adolescents aged 2-18 years was lower than that among Americans. |
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