Validação de um questionário de freqüência de consumo alimentar para população adulta Validation of a food frequency questionnaire for the adult population

OBJETIVO: Investigar a validade e a reprodutibilidade de um questionário de freqüência de consumo alimentar desenvolvido para a população adulta. MÉTODOS: Foram entrevistados, em três momentos, 69 indivíduos, de ambos os sexos, freqüentadores de restaurantes industriais em dois órgãos públicos de Brasília, Distrito Federal. Na primeira e terceira entrevistas foram aplicados um recordatório 24 horas e um questionário de freqüência de consumo alimentar, e na segunda entrevista, um recordatório 24 horas. A duração média do estudo foi de 181 dias. Macronutrientes, vitaminas A e C, cálcio, ferro, zinco, colesterol, fibras e energia total foram analisados utilizando-se os coeficientes de correlação intraclasse e de Pearson, este último na forma bruta e deatenuada. RESULTADOS: Quanto à reprodutibilidade, o questionário de freqüência de consumo alimentar obteve desempenho adequado, apresentando resultados acima de 0,7 para lipídeo, colesterol, energia e proteína. Para a validade, os melhores coeficientes deatenuados foram observados para vitamina C (r=0,66), ferro (r=0,58), proteína (r=0,55) e carboidrato (r=0,55) e os piores, para colesterol (r=0,32) e vitamina A (r=0,37). CONCLUSÃO: A obtenção de coeficientes de correlação expressivos para alguns nutrientes indica que este questionário de freqüência de consumo alimentar constitui-se em um bom instrumento de pesquisa para estudos epidemiológicos em população adulta, podendo fornecer informações importantes para a implementação de ações na área de saúde e nutrição.<br>OBJECTIVE: The aim of the present study was to investigate the validity and reproducibility of a food frequency questionnaire developed for the adult population. METHODS: Sixty-nine individuals from both genders who attended industrial restaurants from two government divisions in Brasília, Federal District, Brazil, were interviewed on three different occasions. In the first and third interviews, a 24h recall and a food frequency questionnaire were applied, and in the second interview only a 24h recall was applied. The study lasted 181 days. Macronutrients, vitamins A and C, calcium, iron, zinc, cholesterol, fibers and total energy were analyzed using the intraclass and Pearson's correlation coefficients, this last one in a crude and deattenuated manner. RESULTS: Regarding reproducibility, the food frequency questionnaire provided adequate results, presenting correlation coefficients above 0.7 for lipid, cholesterol, energy and protein. For validity, the best deattenuated coefficients were observed for vitamin C (r=0.66), iron (r=0.58), protein (r=0.55) and carbohydrate (r=0.55) and the worst for cholesterol (r=0.32) and vitamin A (r=0.37). CONCLUSION: The expressive correlation coefficients obtained for some nutrients indicates that this food frequency questionnaire constitutes a good research instrument for epidemiological studies in the adult population, as it can supply important dietary information allowing the implementation of actions in the health and nutrition areas

A methodological report from the Malmö Diet and Cancer study: development and evaluation of altered routines in dietary data processing

Background: In the Malmö Diet and Cancer study, information on dietary habits was obtained through a modified diet history method, combining a 7-day menu book for cooked meals and a diet questionnaire for foods with low day-to-day variation. Half way through the baseline data collection, a change of interview routines was implemented in order to reduce interview time. Methods: Changes concentrated on portion-size estimation and recipe coding of mixed dishes reported in the menu book. All method development and tests were carefully monitored, based on experiential knowledge, and supplemented with empirical data. A post hoc evaluation study using "real world" data compared observed means of selected dietary variables before and after the alteration of routines handling dietary data, controlling for potential confounders. Results: These tests suggested that simplified coding rules and standard portion-sizes could be used on a limited number of foods, without distortions of the group mean nutrient intakes, or the participants' ranking. The post hoc evaluation suggested that mean intakes of energy-adjusted fat were higher after the change in routines. The impact appeared greater in women than in men. Conclusions: Future descriptive studies should consider selecting subsets assessed with either method version to avoid distortion of observed mean intakes. The impact in analytical studies may be small, because method version and diet assistant explained less than 1 percent of total variation. The distribution of cases and non-cases across method versions should be monitored