Development of a Food-Based Diet Quality Scale for Brazilian Schoolchildren Using Item Response Theory.

Item response theory (IRT) is a psychometric method that provides probabilistic model-based measurements. Its use is relatively recent in the assessment of food consumption, especially through dietary assessment tools. This study aims (1) to develop a food-based diet quality scale for Brazilian schoolchildren using IRT, and (2) to apply the scale to a representative sample of schoolchildren from a Southern Brazilian city. The scale was developed with daily consumption frequency of foods from 835 students who completed the Food Intake and Physical Activity of Schoolchildren questionnaire. Questionnaire foods were grouped into 10 items according to their nutritional similarities and were evaluated by full-information factor analysis that indicated a dominant factor explaining 28% of the variance. Psychometric item analysis was performed using Samejima's model. The scale covered all levels of diet quality, from "very poor" (scores < 95) to "very good" (scores ≥ 130). Children who had higher diet quality scores consumed beans, meat, fish, eggs, fruits, vegetables, dairy products, and water more frequently, while reducing the consumption of ultraprocessed sugary foods, ultraprocessed savoury snacks and sausages, and sugary drinks. Of 6323 children, an average of less than 10% consumed the highest diet quality scores (good or very good diet quality) and about 60% of children consumed low diet quality scores. The scale can be applied to other schoolchildren with the same measure precision.

Sedentary behavior during school-time: Sociodemographic, weight status, physical education class, and school performance correlates in Brazilian schoolchildren.

OBJECTIVES: To investigate whether sedentary behavior during school-time is associated with gender, age, mother's education, having physical education classes, weight status, and academic performance. DESIGN: Cross-sectional study. METHODS: A sample of 571 children (7-12 years old) from five elementary schools in Florianopolis, South Brazil had their height and weight measured, and wore accelerometers during class time. Teachers completed a form to evaluate children's reading and writing skills. Parents provided sociodemographic and educational information. Data was analyzed using multilevel linear regression analyses. RESULTS: Children spent an average of 132min in sedentary behavior during school-time (64% of total school-time). Girls (137.5min), obese children (138.1min), older children (144.2min), and those who did not have physical education classes (140.2min) spent more time engaged in sedentary activities than their peers. Academic performance and mother's education were not associated with sedentary behaviors. CONCLUSIONS: Children spent most of their school-time in sedentary activities, with girls, older students, and obese students being even more sedentary than their peers. Physical education classes were a protective factor against excessive sedentary behavior in school. Interventions for reducing sedentary behavior during school-time could employ additional strategies to benefit the at risk groups. In addition, encouraging student's participation in physical education classes could minimize the time spent in sedentary behavior during school hours.

Dietary patterns associated with overweight and obesity among Brazilian schoolchildren: an approach based on the time-of-day of eating events.

Several studies reported that the timing of eating events has critical implications in the prevention of obesity, but dietary patterns regarding the time-of-day have not been explored in children. The aim of this study was to derive latent food patterns of daily eating events and to examine their associations with overweight/obesity among schoolchildren. A population-based cross-sectional study was conducted with 7-10-year-old Brazilian schoolchildren (n 1232) who completed the Previous Day Food Questionnaire, illustrated with twenty-one foods/beverages in six daily eating events. Latent class analysis was used to derive dietary patterns whose association with child weight status was evaluated by multivariate multinomial regression. Four mutually exclusive latent classes of dietary patterns were identified and labelled according to the time-of-day of eating events and food intake probability (FIP): (A) higher FIP only at lunch; (B) lower FIP at all eating events; (C) higher FIP at lunch, afternoon and evening snacks; (D) lower FIP at breakfast and at evening snack, higher FIP at other meals/snacks. The percentages of children within these classes were 32·3, 48·6, 15·1 and 4·0 %, respectively. After controlling for potential confounders, the mean probabilities of obesity for these classes were 6 % (95 % CI 3·0, 9·0), 13 % (95 % CI 9·0, 17·0), 12 % (95 % CI 6·0, 19) and 11 % (95 % CI 5·0, 17·0), in the same order. In conclusion, the children eating traditional lunch with rice and beans as the main meal of the day (class A) had the lowest obesity risk, thus reinforcing the importance of both the food type and the time-of-day of its intake for weight status.

The use of multiple imputation method for the validation of 24-h food recalls by part-time observation of dietary intake in school.

External validation of food recall over 24 h in schoolchildren is often restricted to eating events in schools and is based on direct observation as the reference method. The aim of this study was to estimate the dietary intake out of school, and consequently the bias in such research design based on only part-time validated food recall, using multiple imputation (MI) conditioned on the information on child age, sex, BMI, family income, parental education and the school attended. The previous-day, web-based questionnaire WebCAAFE, structured as six meals/snacks and thirty-two foods/beverage, was answered by a sample of 7-11-year-old Brazilian schoolchildren (n 602) from five public schools. Food/beverage intake recalled by children was compared with the records provided by trained observers during school meals. Sensitivity analysis was performed with artificial data emulating those recalled by children on WebCAAFE in order to evaluate the impact of both differential and non-differential bias. Estimated bias was within ±30 % interval for 84·4 % of the thirty-two foods/beverages evaluated in WebCAAFE, and half of the latter reached statistical significance (P<0·05). Rarely (<3 %) consumed dietary items were often under-reported (fish/seafood, vegetable soup, cheese bread, French fries), whereas some of those most frequently reported (meat, bread/biscuits, fruits) showed large overestimation. Compared with the analysis restricted to fully validated data, MI reduced differential bias in sensitivity analysis but the bias still remained large in most cases. MI provided a suitable statistical framework for part-time validation design of dietary intake over six daily eating events.

Longitudinal and cross-sectional changes in active commuting to school among Brazilian schoolchildren.

OBJECTIVE: The objective of the study is to evaluate cross-sectional and longitudinal changes in children's commuting to school in a representative sample of a Brazilian city. METHODS: Two school-based studies were carried out in 2002 (n=2936; 7-10 years old) and 2007 (n=1232; 7-15 years old) in Florianopolis, Brazil. Cross-sectional data were collected from children aged 7 to 10 years in 2002 and 2007. Longitudinal analyses were performed with data from 733 children participating in both surveys. Children self-reported their mode of transportation to school using a validated illustrated questionnaire. Changes were tested with chi square statistics and McNemar's test. RESULTS: Cross-sectional data showed a 17% decline in active commuting; a decrease from 49% in 2002 to 41% in 2007. On the other hand, active commuting among the 733 children increased as they entered adolescence 5 years later, rising from 40% to 49%. CONCLUSION: Active commuting to school decreased in Brazilian children aged 7-10 years over a five year period; whereas, it increased among children entering adolescence. Policies should focus on safety and environmental determinants to increase active commuting.

Methods and participant characteristics of a randomized intervention to promote physical activity and healthy eating among brazilian high school students: the Saude na Boa project.

BACKGROUND: A cross-cultural, randomized study was proposed to observe the effects of a school-based intervention designed to promote physical activity and healthy eating among high school students in 2 cities from different regions in Brazil: Recife and Florianopolis. The objective of this article is to describe the methodology and subjects enrolled in the project. METHODS: Ten schools from each region were matched and randomized into intervention and control conditions. A questionnaire and anthropometry were used to collect data in the first and last month of the 2006 school year. The sample (n=2155 at baseline; 55.7% females; 49.1% in the experimental group) included students 15 to 24 years, attending nighttime classes. The intervention focused on simple environmental/organizational changes, diet and physical activity education, and personnel training. RESULTS: The central aspects of the intervention have been implemented in all 10 intervention schools. Problems during the intervention included teachers' strikes in both sites and lack of involvement of the canteen owners in schools. CONCLUSIONS: The Saude na Boa study provides evidence that public high schools in Brazil represent an important environment for health promotion. Its design and simple measurements increase the chances of it being sustained and disseminated to similar schools in Brazil.