Validity and reproducibility of a food frequency questionnaire for adults of São Paulo, Brazil

OBJECTIVES: To assess the validity and reproducibility of a food frequency questionnaire developed for estimating the food consumption of adults in São Paulo, Brazil, based population study. METHODS: A sample of individuals aged above 20 years, of both genders, living in São Paulo, was used for the validation study (n = 77) and reproducibility study (n = 74) of the food frequency questionnaire. To verify the validity and reproducibility of energy and 19 nutrients were applied two food frequency questionnaires (60 items) and three 24-hour dietary recalls (24HR - reference method). The validity was verified by Spearman correlation coefficient (crude and de-attenuated) and weighted Kappa, and reproducibility by intraclass correlation coefficients and weighted kappa. RESULTS: In analyzes of validity de-attenuated correlation coefficients ranged from 0.21 (carbohydrate) to 0.74 (energy), and weighted kappa exceeded 0.40 for 30% of the nutrients. Polyunsaturated fat and folate did not show significant correlation and weighted kappa. In reproducibility correlation coefficients ranged from 0.36 (polyunsaturated fat) to 0.69 (calcium), and weighted kappa exceeded 0.40 for 80% of the nutrients. CONCLUSION: The food frequency questionnaire analyzed has good validity and reproducibility for estimating the food consumption of adults in São Paulo compared to the reference method, so it is an appropriate instrument to be used in epidemiological studies on similar populations. Estimates of polyunsaturated fat and folate should be interpreted with caution.

Associations between dietary patterns and self-reported hypertension among Brazilian adults: a cross-sectional population-based study

Hypertension is a prevalent cardiovascular disease, the important modifiable risk factor of which is diet. The aim of this study was to derive dietary patterns and to test associations with self-reported hypertension and other characteristics, namely demographic, socioeconomic, and lifestyle factors. Data were obtained from the population-based cross-sectional study titled Health Survey of the City of São Paulo, with a random sample of residents of the city of São Paulo, Brazil, aged older than 20 years of both sexes (n=1,102). In 2008, a structured questionnaire with information about socioeconomic, anthropometric, lifestyle, and dietary factors was applied. Dietary intake was estimated by two 24-hour dietary recalls, adjusted by Multiple Source Method. Dietary patterns were obtained through exploratory principal component factor analysis. Poisson regression was used to assess relationships. Three dietary patterns were identified: prudent (fruits, vegetables, whole-grain bread, white cheeses, juices, reduced-fat milk/nonfat milk), traditional (rice, beans, bread/toast/crackers, butter/margarine, whole milk, coffee/teas, sugar), and modern (sodas, pastries/sandwiches/pizzas, yellow cheeses, pastas, sauces, alcoholic beverages, sweets, processed meats). Hypertension and demographic, socioeconomic, and lifestyle factors, as well as the presence of health insurance, were associated with adherence to one or more identified dietary patterns. These results suggest the existence of a target audience for planning and executing public policies of food and nutrition to prevent and control hypertension.

Empirically derived dietary patterns: interpretability and construct validity according to different factor rotation methods

This study aimed to investigate the effects of factor rotation methods on interpretability and construct validity of dietary patterns derived in a representative sample of 1,102 Brazilian adults. Dietary patterns were derived from exploratory factor analysis. Orthogonal (varimax) and oblique rotations (promax, direct oblimin) were applied. Confirmatory factor analysis assessed construct validity of the dietary patterns derived according to two factor loading cut-offs (≥ |0.20| and ≥ |0.25|). Goodness-of-fit indexes assessed the model fit. Differences in composition and in interpretability of the first pattern were observed between varimax and promax/oblimin at cut-off ≥ |0.20|. At cut-off ≥ |0.25|, these differences were no longer observed. None of the patterns derived at cut-off ≥ |0.20| showed acceptable model fit. At cut-off ≥ |0.25|, the promax rotation produced the best model fit. The effects of factor rotation on dietary patterns differed according to the factor loading cut-off used in exploratory factor analysis.

Prevalência e fatores associados à anemia entre crianças atendidas em creches públicas de São Paulo

Um dos grandes desafios na saúde pública é o combate à anemia ferropriva em crianças. Considerando a importância da cidade de São Paulo em relação ao tamanho da sua população e a escassez de estudos representativos de crianças que freqüentam creches, este estudo teve como objetivo analisar a prevalência de anemia em uma amostra probabilística de crianças freqüentadoras de creches da rede municipal de São Paulo e identificar os fatores associados. Este é um estudo transversal com 330 pré-escolares sorteados entre 20 creches públicas. Anemia foi definida como hemoglobina menor de 11g/dL. Utilizou-se regressão logística hierarquizada para análise múltipla. A prevalência de anemia foi de 68,8% (IC95% = 63,8%; 73,8%). Entre as crianças com anemia, o percentual de anemia grave (< 9,5g/dL) foi de 26,9%. Estiveram associados à anemia idade menor de 24 meses (Odds ratio (OR) = 2,7; IC95% = 1,4; 5,2) e idade do responsável pela criança menor de 25 anos (OR = 1,8; IC95% = 1,0; 3,2). A prevalência de anemia foi alta quando comparada a outros estudos. O acompanhamento de programas de combate a esta doença deve ser realizado e modificado, quando necessário, especialmente entre crianças freqüentadoras de creches públicas menores de dois anos que possuem responsáveis mais jovens.