Search

Abstract Background Validity of self-reported height and weight has not been adequately evaluated in diverse adolescent populations. In fact there are no reported validity studies conducted in Asian children and adolescents. This study aims to examine the accuracy of self-reported weight, height, and resultant BMI values in Chinese adolescents, and of the adolescents' subsequent classification into overweight categories. Methods Weight and height were self-reported and measured in 1761 adolescents aged 12-16 years in a cross-sectional survey in Xi'an city, China. BMI was calculated from both reported values and measured values. Bland-Altman plots with 95% limits of agreement, Pearson's correlation and Kappa statistics were calculated to assess the agreement. Results The 95% limits of agreement were -11.16 and 6.46 kg for weight, -4.73 and 7.45 cm for height, and -4.93 and 2.47 kg/m2 for BMI. Pearson correlation between measured and self-reported values was 0.912 for weight, 0.935 for height and 0.809 for BMI. Weighted Kappa was 0.859 for weight, 0.906 for height and 0.754 for BMI. Sensitivity for detecting overweight (includes obese) in adolescents was 56.1%, and specificity was 98.6%. Subjects' area of residence, age and BMI were significant factors associated with the errors in self-reporting weight, height and relative BMI. Conclusions Reported weight and height does not have an acceptable agreement with measured data. Therefore, we do not recommend the application of self-reported weight and height to screen for overweight adolescents in China. Alternatively, self-reported data could be considered for use, with caution, in surveillance systems and epidemiology studies.

Abstract Background Adequate maternal nutrient intake during pregnancy is important to ensure satisfactory birth outcomes. There are no data available on the usual dietary intake among pregnant women in rural China. The present study describes and evaluates the dietary intake in a cohort of pregnant women living in two counties of rural Shaanxi, western China. Methods 1420 pregnant women were recruited from a trial that examined the effects of micronutrient supplementation on birth outcomes. Dietary information was collected at the end of their trimester or after delivery with an interviewed-administrated semi-quantitative food frequency questionnaire (FFQ). Nutrients intake was calculated from the FFQ and compared to the Estimated Average Requirements (EAR). The EAR cut-offs based on the Chinese Nutrition Society Dietary Reference Intakes (DRIs) were used to assess the prevalence of inadequate dietary intakes of energy, protein, calcium, zinc, riboflavin, vitamin C and folate. Mann-Whitney U and Kruskal Wallis tests were used to compare nutrient intakes across subgroups. Results The mean nutrient intakes assessed by the FFQ was similar to those reported in the 2002 Chinese National Nutrition and Health Survey from women living in rural areas except for low intakes of protein, fat, iron and zinc. Of the participants, 54% were at risk of inadequate intake of energy. There were high proportions of pregnant women who did not have adequate intakes of folate (97%) and zinc (91%). Using the "probability approach", 64% of subjects had an inadequate consumption of iron. Conclusion These results reveal that the majority of pregnant women in these two counties had low intakes of nutrients that are essential for pregnancy such as iron and folate. Trial registration ISRCTN08850194.

Background: To explore the extent and nature of television food advertising especially unhealthy food advertising to primary school children in Xi'an, China.Methods: Television data were recorded for 2 weekdays and 2 weekend days between 6:00 and 22:00 during May and June in 2012 from a total of five television channels most popular with children in Xi'an. Pearson χ (2) tests and logistic regression were applied to determine differences in the proportion of healthy food, unhealthy food and miscellaneous food advertisements for different channels, programs, dates, viewing periods and the use of persuasive marketing tactics.Results: Of the 5527 advertisements transcribed, 25.5 % were for food, among which 48.1 % were considered to be unhealthy. The frequency of food advertisements was 6 per hour per channel, including 3 unhealthy food advertisements. Compared with healthy and miscellaneous food advertisements, more unhealthy food advertisements were shown during afternoon, weekends and children's non-peak viewing times as well as on children's television channels, central television channels and non-children's programmes. Unhealthy foods contributed the highest proportion of all food advertisements containing promotional characters (51.7 %) and premium offers (59.1 %). Both promotional characters and premium offers appeared more on non-children's television channels.Conclusions: The majority of food advertisements were for unhealthy food. More unhealthy food ads were shown in children's non-peak time and afternoon as well as non-children's channels. More children-oriented persuasive marketing tactics were used in unhealthy food ads especially in non-children's channels. Therefore, intervening in the entrance of unhealthy foods into the market and establishing regulations related to food advertising especially unhealthy food advertisements are important strategies to prevent children's exposure to unhealthy food and childhood obesity. [ABSTRACT FROM AUTHOR]

Background: Validity of self-reported height and weight has not been adequately evaluated in diverse adolescent populations. In fact there are no reported validity studies conducted in Asian children and adolescents. This study aims to examine the accuracy of self-reported weight, height, and resultant BMI values in Chinese adolescents, and of the adolescents' subsequent classification into overweight categories.Methods: Weight and height were self-reported and measured in 1761 adolescents aged 12-16 years in a cross-sectional survey in Xi'an city, China. BMI was calculated from both reported values and measured values. Bland-Altman plots with 95% limits of agreement, Pearson's correlation and Kappa statistics were calculated to assess the agreement.Results: The 95% limits of agreement were -11.16 and 6.46 kg for weight, -4.73 and 7.45 cm for height, and -4.93 and 2.47 kg/m2 for BMI. Pearson correlation between measured and self-reported values was 0.912 for weight, 0.935 for height and 0.809 for BMI. Weighted Kappa was 0.859 for weight, 0.906 for height and 0.754 for BMI. Sensitivity for detecting overweight (includes obese) in adolescents was 56.1%, and specificity was 98.6%. Subjects' area of residence, age and BMI were significant factors associated with the errors in self-reporting weight, height and relative BMI.Conclusions: Reported weight and height does not have an acceptable agreement with measured data. Therefore, we do not recommend the application of self-reported weight and height to screen for overweight adolescents in China. Alternatively, self-reported data could be considered for use, with caution, in surveillance systems and epidemiology studies. [ABSTRACT FROM AUTHOR]